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Welding, Joining, and Additive Manufacturing of Metals and Alloys
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Welding, Joining, and Additive Manufacturing of Metals and Alloys

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: closed (10 June 2024) | Viewed by 30348

Special Issue Editors

Dr. Damjan Klobcar

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Guest Editor
Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia
Interests: additive manufacturing; characterization of weld joints; ultrasonic welding; laser welding; friction stir welding; friction welding; resistance spot welding; arc welding technologies; adhesive bonding
Special Issues, Collections and Topics in MDPI journals
Dr. Abhay Sharma

E-Mail Website
Guest Editor
Department of Materials Engineering, KU Leuven, Campus De Nayer, 2860 Sint-Katelijne Waver, Belgium
Interests: welding engineering; process modelling; additive manufacturing; sustainable manufacturing; friction stir welding
Dr. Prakash Srirangam

E-Mail Website
Guest Editor
WMG, International Manufacturing Centre, The University of Warwick, Coventry CV4 7AL, UK
Interests: light alloys; dissimilar metals joining; advanced characterization

Special Issue Information

Dear Colleagues,

The constant development of new materials and products also promotes the research and development of welding, joining and build-up welding technologies as well as additive manufacturing technologies. These investigations are multidisciplinary, and include processes, materials, the weldability and joinability of materials and alloys, the design of products and joints, and numerical simulations to comprehensively understand physical and metallurgical phenomena. A successful understanding of these phenomena enables the development of solutions to overcome these problems. This Special Issue aims to report basic and applied research results as well as case studies related to the weldability and joinability of materials and additive manufacturing.

The potential topics for the Special Issues include, but are not limited to:

  • Micro and nano joining;
  • Diffusion bonding;
  • Adhesive bonding;
  • Hybrid welding and additive manufacturing;
  • Laser welding;
  • Welding with mechanical energy;
  • Weldability of similar and dissimilar materials;
  • Advanced material characterization;
  • Residual stress and distortion;
  • Numerical modeling and simulation;
  • Additive manufacturing processes (DED, powder bed fusion, binder jetting, etc.);
  • Additive manufacturing of new materials, multi-materials and functionally graded materials;
  • Improvement of materials using weld surfacing and additive manufacturing;
  • Repair welding and repair additive manufacturing of products.

Dr. Damjan Klobcar
Dr. Abhay Sharma
Dr. Prakash Srirangam
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • welding and joining technologies
  • brazing and soldering
  • additive manufacturing
  • adhesive bonding
  • weldability of materials

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Related Special Issue

Published Papers (20 papers)

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Research

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8 pages, 11149 KiB  
Communication
Eliminating Cu–Cu Bonding Interfaces Using Electroplated Copper and (111)-Oriented Nanotwinned Copper
by Tsan-Feng Lu, Yuan-Fu Cheng, Pei-Wen Wang, Yu-Ting Yen and YewChung Sermon Wu
Materials 2024, 17(14), 3467; https://doi.org/10.3390/ma17143467 - 13 Jul 2024
Viewed by 1029
Abstract
Cu–Cu joints have been adopted for ultra-high-density packaging for high-end devices. However, the atomic diffusion rate is notably low at the preferred processing temperature, resulting in clear and distinct weak bonding interfaces, which, in turn, lead to reliability issues. In this study, a [...] Read more.
Cu–Cu joints have been adopted for ultra-high-density packaging for high-end devices. However, the atomic diffusion rate is notably low at the preferred processing temperature, resulting in clear and distinct weak bonding interfaces, which, in turn, lead to reliability issues. In this study, a new method for eliminating the bonding interfaces using two types of Cu films in Cu–Cu bonding is proposed. The difference in grain size was utilized as the primary driving force for the migration of bonding interfaces/interfacial grain boundaries. Additionally, the columnar nanotwinned Cu structure acted as a secondary driving force, making the migration more significant. When bonded at 300 °C, the grains from one side grew and extended to the bottom, eliminating the bonding interfaces. A mechanism for the evolution of the Cu bonding interfaces/interfacial grain boundaries is proposed. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
►▼ Show Figures

Figure 1

Figure 1
<p>AFM topography images of (<b>a</b>) BCu and (<b>b</b>) NtCu films.</p> Full article ">Figure 2
<p>Plane-view EBSD OIM images of (<b>a</b>) BCu and (<b>b</b>) NtCu films. The BCu film exhibited random orientation, while the NtCu film was highly (111)-oriented. The average grain sizes of the BCu film and NtCu film were 7.18 μm and 0.73 μm, respectively.</p> Full article ">Figure 3
<p>Cross-sectional SEM images after bonding at 300 °C for 1 h: (<b>a</b>) B/B, (<b>b</b>) Nt/Nt, and (<b>c</b>) B/Nt. (<b>d</b>) High-magnification image of the red dotted area in (<b>a</b>). (<b>e</b>) High-magnification image of the red dotted area in (<b>b</b>). (<b>f</b>) High-magnification image of the red dotted area in (<b>c</b>). Note: In (<b>a</b>–<b>c</b>), the bonding interfaces/IGBs are represented by orange dashed lines, and in (<b>c</b>), the white arrows point to the locations of triple junctions (TJs).</p> Full article ">Figure 4
<p>Cross-sectional SEM images after bonding at 300 °C for 2 h: (<b>a</b>) B/B, (<b>b</b>) Nt/Nt, and (<b>c</b>) B/Nt. Note: The bonding interfaces/IGBs are depicted with orange dashed lines and the white arrows in (<b>c</b>) indicate the locations of triple junctions (TJs).</p> Full article ">Figure 5
<p>A schematic diagram illustrating the evolution of the B/Nt bonding interfaces/IGBs. (<b>a</b>) Cu films in contact at room temperature. (<b>b</b>) IGBs formed during the annealing process. (<b>c</b>) Grain growth across the IGBs consumed twin boundaries to reduce the grain boundary energy. (<b>d</b>) The grains on the BCu side further grew into the NtCu side and extended to the bottom.</p> Full article ">
18 pages, 4919 KiB  
Article
Evolution of Material Properties and Residual Stress with Increasing Number of Passes in Aluminium Structure Printed via Additive Friction Stir Deposition
by Vladislav Yakubov, Halsey Ostergaard, James Hughes, Evren Yasa, Michail Karpenko, Gwénaëlle Proust and Anna M. Paradowska
Materials 2024, 17(14), 3457; https://doi.org/10.3390/ma17143457 - 12 Jul 2024
Cited by 3 | Viewed by 1546
Abstract
Additive friction stir deposition (AFSD) is an emerging solid-state additive manufacturing process with a high deposition rate. Being a non-fusion additive manufacturing (AM) process, it significantly eliminates problems related to melting such as cracking or high residual stresses. Therefore, it is possible to [...] Read more.
Additive friction stir deposition (AFSD) is an emerging solid-state additive manufacturing process with a high deposition rate. Being a non-fusion additive manufacturing (AM) process, it significantly eliminates problems related to melting such as cracking or high residual stresses. Therefore, it is possible to process reactive materials or high-strength alloys with high susceptibility to cracking. Although the residual stresses are lower in this process than with the other AM processes, depending on the deposition path, geometry, and boundary conditions, residual stresses may lead to undesired deformations and deteriorate the dimensional accuracy. Thermal cycling during layer deposition, which also depends on the geometry of the manufactured component, is expected to affect mechanical properties. To this day, the influence of the deposit geometry on the residual stresses and mechanical properties is not well understood, which presents a barrier for industry uptake of this process for large-scale part manufacturing. In this study, a stepped structure with 4, 7, and 10 passes manufactured via AFSD is used to investigate changes in microstructure, residual stress, and mechanical property as a function of the number of passes. The microstructure and defects are assessed using scanning electron microscopy and electron backscatter diffraction. Hardness maps for each step are created. The residual stress distributions at the centreline of each step are acquired via non-destructive neutron diffraction. The valuable insights presented here are essential for the successful utilisation of AFSD in industrial applications. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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Figure 1

Figure 1
<p>(<b>a</b>) Three-dimensional render of investigated AFSD-manufactured structure showing top ¾ view; (<b>b</b>) side view of as-manufactured sample; (<b>c</b>) illustration of hardness testing planes (blue) and neutron residual stress measurement paths (red).</p> Full article ">Figure 2
<p>Optical images showing cross-section of (<b>a</b>) 4-pass deposit, (<b>b</b>) 7-pass deposit, and (<b>c</b>) 10-pass deposit. SEM images showing (<b>d</b>) defect-free deposit and substrate interface and (<b>e</b>) defective deposit and substrate interface, with locations provided in (<b>b</b>). BD indicates build direction.</p> Full article ">Figure 3
<p>SEM image of deposit and EDS images showing Fe and Si distribution are provided as (<b>a</b>), (<b>b</b>), and (<b>c</b>), respectively, with imaged location provided in (<b>l</b>). SEM image of deposit and substrate interface and EDS images showing Fe and Si distribution are provided as (<b>d</b>), (<b>e</b>), and (<b>f</b>), respectively, with imaging location provided in (<b>l</b>). SEM image of substrate and EDS images showing Fe and Si distribution are provided as (<b>g</b>), (<b>h</b>), and (<b>i</b>), respectively, with imaging location provided in (<b>l</b>). (<b>j</b>) EBSD of deposit at location provided in (<b>a</b>); (<b>k</b>) EBSD of substrate at location provided in (<b>l</b>). BD indicates build direction.</p> Full article ">Figure 4
<p>Hardness distribution for (<b>a</b>) 4-pass, (<b>b</b>) 7-pass, and (<b>c</b>) 10-pass deposits. The region between the dashed lines is the low-hardness zone.</p> Full article ">Figure 5
<p>Hardness along deposit centreline for 4-pass, 7-pass, and 10-pass deposits.</p> Full article ">Figure 6
<p>The d<sub>0</sub>∔spacings determined from ND data. Applied d<sub>0</sub> refers to values used for residual stress calculation. Estimated d<sub>0</sub> was calculated from 10-pass deposit data by assuming strain-free normal principal direction and was used for comparison with reference d<sub>0</sub> value. Reference d<sub>0</sub> is raw value determine from strain-free reference sample.</p> Full article ">Figure 7
<p>ND principal data for 10-pass deposit indicating (<b>a</b>) d∔spacing, (<b>b</b>) normalised FWHM, and (<b>c</b>) normalised intensity.</p> Full article ">Figure 8
<p>ND principal microstrain data for (<b>a</b>) 4-pass, (<b>b</b>) 7-pass, and (<b>c</b>) 10-pass deposits.</p> Full article ">Figure 9
<p>ND principal residual stress data for (<b>a</b>) 4-pass, (<b>b</b>) 7-pass, and (<b>c</b>) 10-pass deposits.</p> Full article ">Figure 10
<p>The 4-pass, 7-pass, and 10-pass deposit ND residual stress data for the (<b>a</b>) normal (build direction), (<b>b</b>) transverse, and (<b>c</b>) longitudinal principal directions.</p> Full article ">
11 pages, 8775 KiB  
Article
Modification of Microstructure and Mechanical Properties of Extruded AZ91-0.4Ce Magnesium Alloy through Addition of Ca
by Fengtao Ni, Jian Peng, Xiangquan Liu, Pan Gao, Zhongkui Nie, Jie Hu and Dong Zhao
Materials 2024, 17(13), 3359; https://doi.org/10.3390/ma17133359 - 8 Jul 2024
Cited by 2 | Viewed by 884
Abstract
The effect of the addition of alkali earth element Ca on the microstructure and mechanical properties of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys was studied by using scanning electron microscopy, transmission electron microscopy, and tensile tests. The results showed [...] Read more.
The effect of the addition of alkali earth element Ca on the microstructure and mechanical properties of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys was studied by using scanning electron microscopy, transmission electron microscopy, and tensile tests. The results showed that the addition of Ca could significantly refine the second phase and grain size of the extruded AZ91-0.4Ce alloy. The refinement effect was most obvious when 0.8 wt.% of Ca was added, and the recrystallized grain size was 4.75 μm after extrusion. The addition of Ca resulted in the formation of a spherical Al2Ca phase, which effectively suppressed the precipitation of the β-Mg17Al12 phase, promoted dynamic recrystallization and grain refinement, impeded dislocation motion, and exerted a positive influence on the mechanical properties of the alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of the AZ91-0.4Ce-0.8Ca alloy were 238.7 MPa, 338.3 MPa, and 10.8%, respectively. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Microstructure scanning and energy spectrum analysis of as-cast AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys. (<b>a</b>) AZ91-0.4Ce alloy, (<b>b</b>) AZ91-0.4Ce-0.4Ca alloy, (<b>c</b>) AZ91-0.4Ce-0.8Ca alloy, and (<b>d</b>) AZ91-0.4Ce-1.2Ca alloy. (<b>a1</b>–<b>d1</b>) correspond to selected parts in box (<b>a</b>–<b>d</b>), respectively.</p> Full article ">Figure 2
<p>XRD pattern of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys.</p> Full article ">Figure 3
<p>Microstructure scanning and energy spectrum analysis of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys. (<b>a</b>) AZ91-0.4Ce alloy, (<b>b</b>) AZ91-0.4Ce-0.4Ca alloy, (<b>c</b>) AZ91-0.4Ce-0.8Ca alloy, and (<b>d</b>) AZ91-0.4Ce-1.2Ca alloy.</p> Full article ">Figure 4
<p>Extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys’ pole figure and inverse pole figure. (<b>a</b>) AZ91-0.4Ce alloy, (<b>b</b>) AZ91-0.4Ce-0.4Ca alloy, (<b>c</b>) AZ91-0.4Ce-0.8Ca alloy, and (<b>d</b>) AZ91-0.4Ce-1.2Ca alloy.</p> Full article ">Figure 5
<p>Mechanical properties of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys at room temperature: (<b>a</b>) stress–strain curve; (<b>b</b>) variation trend of UTS, YS, and EL.</p> Full article ">Figure 6
<p>Effect of second-phase distribution and size on grain growth. (<b>a</b>) Coarse second phase; (<b>b</b>) fine dispersion of second phase (red arrows represent direction of grain boundary movement).</p> Full article ">Figure 7
<p>(<b>a</b>–<b>c</b>) Bright-field transmission electron microscope (TEM) micrographs of the as-extruded AZ91-0.4Ce-0.8Ca alloy; (<b>e</b>,<b>f</b>) the corresponding diffraction patterns of the selected particles taken from (<b>a</b>,<b>b</b>), indicated by the arrows A, B, respectively; (<b>d</b>) a high-resolution TEM (HRTEM) image of the zone C in (<b>c</b>); (<b>g</b>) an inverse fast Fourier transform (IFFT) image of the zone D in (<b>d</b>) (remark: the “T”-shaped symbols represent the dislocations).</p> Full article ">Figure 8
<p>The Statistical of the recrystallization grains and the Schmid factor of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys. (<b>a</b>) AZ91-0.4Ce alloy, (<b>b</b>) AZ91-0.4Ce-0.4Ca alloy, (<b>c</b>) AZ91-0.4Ce-0.8Ca alloy, and (<b>d</b>) AZ91-0.4Ce-1.2Ca alloy.</p> Full article ">
16 pages, 29047 KiB  
Article
Comparison between Mechanical Properties and Joint Performance of AA 2024-T351 Aluminum Alloy Welded by Friction Stir Welding, Metal Inert Gas and Tungsten Inert Gas Processes
by Miodrag Milčić, Damjan Klobčar, Dragan Milčić, Nataša Zdravković, Aleksija Đurić and Tomaž Vuherer
Materials 2024, 17(13), 3336; https://doi.org/10.3390/ma17133336 - 5 Jul 2024
Cited by 1 | Viewed by 881
Abstract
The aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as [...] Read more.
The aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as by the solid-state welding process, friction stir welding (FSW), which has recently become very important in aluminum and alloy welding. For welding AA2024-T35 with MIG and TIG fusion processes, the filler material ER 4043—AlSi5 was chosen because of reduced cracking. Different methods were used to evaluate the quality of the produced joints, including macro- and microstructure evaluation, in addition to hardness and tensile tests. The ultimate tensile strength (UTS) of the FSW sample was found to be 80% higher than that of MIG and TIG samples. The average hardness value of the weld zone of metal for the MIG- and TIG-produced AA2024-T3511 butt joints showed a significant decrease compared to the hardness of the base metal AA2024-T351 by 50%, while for FSW joints, in the nugget zone, the hardness is about 10% lower relative to the base metal AA2024-T3511. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
►▼ Show Figures

Figure 1

Figure 1
<p>(<b>a</b>) Conventional milling machine for FSW and (<b>b</b>) geometry of FSW tool.</p> Full article ">Figure 2
<p>Hardness measurement points of the joint.</p> Full article ">Figure 3
<p>Microhardness measurement scheme with characteristic zones of welded joint (SZ—stir zone, TMAZ—thermomechanically affected zone, HAZ—heat-affected zone).</p> Full article ">Figure 4
<p>Face side of the welded joint with (<b>a</b>) MIG; (<b>b</b>) TIG; (<b>c</b>) FSW process.</p> Full article ">Figure 4 Cont.
<p>Face side of the welded joint with (<b>a</b>) MIG; (<b>b</b>) TIG; (<b>c</b>) FSW process.</p> Full article ">Figure 5
<p>Macrostructure of a welded joint.</p> Full article ">Figure 6
<p>Appearance of cross-section of the specimen with view of microscopic examination zones—MIG [<a href="#B22-materials-17-03336" class="html-bibr">22</a>].</p> Full article ">Figure 7
<p>EDS spot analysis of MIG joint sample (SEM).</p> Full article ">Figure 8
<p>Appearance of cross-section of the specimen with view of microscopic examination zones—TIG.</p> Full article ">Figure 9
<p>EDS spot analysis of TIG joint sample (SEM).</p> Full article ">Figure 10
<p>The microstructure of FSW joint: (<b>a</b>–<b>e</b>) interface between the SZ and the TMAZ; (<b>f</b>) SZ; (<b>g</b>) BM.</p> Full article ">Figure 11
<p>Ultimate tensile strength, yield strength, and elongation percentage of the similar AA2024-T351 butt joints welded using different techniques.</p> Full article ">Figure 12
<p>Hardness distribution of MIG and TIG butt joints obtained by measuring near the weld face.</p> Full article ">Figure 13
<p>Hardness distribution of MIG and TIG butt joints obtained by measuring near the root of the weld.</p> Full article ">Figure 14
<p>Hardness distribution of FSW butt joint obtained by measuring in the middle, near the face and root of the seam.</p> Full article ">Figure 15
<p>A comparative assessment among hardness levels at the WZ.</p> Full article ">
25 pages, 10756 KiB  
Article
A Methodology for Shielding-Gas Selection in Wire Arc Additive Manufacturing with Stainless Steel
by Felipe Ribeiro Teixeira, Vinicius Lemes Jorge, Fernando Matos Scotti, Erwan Siewert and Americo Scotti
Materials 2024, 17(13), 3328; https://doi.org/10.3390/ma17133328 - 5 Jul 2024
Cited by 1 | Viewed by 980
Abstract
The main objective of this work was to propose and evaluate a methodology for shielding-gas selection in additive manufacturing assisted by wire arc additive manufacturing (WAAM) with an austenitic stainless steel as feedstock. To validate the proposed methodology, the impact of multi-component gases [...] Read more.
The main objective of this work was to propose and evaluate a methodology for shielding-gas selection in additive manufacturing assisted by wire arc additive manufacturing (WAAM) with an austenitic stainless steel as feedstock. To validate the proposed methodology, the impact of multi-component gases was valued using three different Ar-based blends recommended as shielding gas for GMA (gas metal arc) of the target material, using CMT (cold metal transfer) as the process version. This assessment considered features that potentially affect the building of the case study of thin walls, such as metal transfer regularity, deposition time, and geometrical and metallurgical characteristics. Different settings of wire-feed speeds were conceived to maintain a similar mean current (first constraint for comparison’s sake) among the three gas blends. This approach implied different mean wire-feed speeds and simultaneously forced a change in the deposition speed to maintain the same amount of material deposited per unit of length (second comparison constraint). The composition of the gases affects the operational performance of the shielding gases. It was concluded that by following this methodology, shielding-gas selection decision-making is possible based on the perceived characteristics of the different commercial blends. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
►▼ Show Figures

Figure 1

Figure 1
<p>(<b>a</b>) Supplementary shielding-gas nozzles coupled to the welding torch, also emphasising the substrate and fixture during the wall building-up; the layer top surface appearance, (<b>b</b>) without and (<b>c</b>) with the use of the additional shielding.</p> Full article ">Figure 2
<p>Positions of micrographic analyses (red solid-line squares), δ-ferrite quantification (small white dashed-line rectangle), and hardness map (large white dashed-line rectangle); the microhardness measurement region is magnified to show the distances adopted between each indentation.</p> Full article ">Figure 3
<p>Wall deposition with Blend 1 (Ar + 2%CO<sub>2</sub>), WFS<sub>set</sub>= 4.9 m/min; DS<sub>set</sub> = 35 cm/min, CA = −30 and CD = −4): (<b>a</b>) Current (I), voltage (U), and power (P) oscillograms; (<b>b</b>) cyclogram of voltage × current.</p> Full article ">Figure 4
<p>(<b>a</b>) Oscillograms of current (I), voltage (U), and power (P) for a typical CMT cycle; (<b>b</b>) respective voltage × current cyclogram, with the feature regions (1 to 4) that characterise the U and I traces.</p> Full article ">Figure 5
<p>(<b>a</b>) Oscillograms of current (I), voltage (U), and power (P) sampling six CMT cycles; (<b>b</b>) Three voltage × current cyclograms out of the 1st, 3rd, and 6th cycles, respectively; and (<b>c</b>) the oscillograms corresponding to each type of cyclogram identified (A, B, and C), where 1 to 4 are feature regions identified in <a href="#materials-17-03328-f004" class="html-fig">Figure 4</a>.</p> Full article ">Figure 6
<p>(<b>a</b>) Oscillograms of current (I), voltage (U), and power (P), where the brown arrows indicate the arcing-time (t<sub>arc</sub>) semi-period, and the green arrows indicate the short-circuiting time (t<sub>sc</sub>) semi-period; (<b>b</b>) cyclograms of the 15th layer sampling.</p> Full article ">Figure 7
<p>Surface finish (after cleaning with a steel brush) of the walls, using as shielding gases: (<b>a</b>) Blend 1 (Ar + 2%CO<sub>2</sub>); (<b>b</b>) Blend 2 (Ar + 2%H<sub>2</sub> + 20%He + 500 ppm CO<sub>2</sub>); and (<b>c</b>) Blend 3 (Ar + 1%CO<sub>2</sub> + 1%H<sub>2</sub>).</p> Full article ">Figure 8
<p>Geometric characteristics of the main experiments: (<b>a</b>) effective wall width; (<b>b</b>) external wall width; (<b>c</b>) surface waviness; and (<b>d</b>) layer height (standard deviations for surface waviness and layer height were smaller than the resolution of the measurement instruments detailed in <a href="#sec2dot3dot3-materials-17-03328" class="html-sec">Section 2.3.3</a>).</p> Full article ">Figure 9
<p>Total deposition times (T<sub>Dt</sub>) for different layer lengths (triangular, circular, and diamond markers consider lengths of 200, 1000, and 5000 mm, respectively) using Blend 1 (Ar + 2%CO<sub>2</sub>), represented by black continuous lines, Blend 2 (Ar + 2%H<sub>2</sub> + 20%He + 500 ppm CO<sub>2</sub>) by blue dotted lines, and Blend 3 (Ar + 1%CO<sub>2</sub> + 1%H<sub>2</sub>) by orange dashed and dotted lines.</p> Full article ">Figure 10
<p>Cross-section macrograph of the walls: (<b>a</b>) Blend 1 (Ar + 2%CO<sub>2</sub>); (<b>b</b>) Blend 2 (Ar + 2%H<sub>2</sub> + 20%He + 500 ppm CO<sub>2</sub>); and (<b>c</b>) Blend 3 (Ar + 1%CO<sub>2</sub> + 1%H<sub>2</sub>).</p> Full article ">Figure 11
<p>Microhardness maps of the walls: (<b>a</b>) Blend 1 (Ar + 2%CO<sub>2</sub>); (<b>b</b>) Blend 2 (Ar + 2%H<sub>2</sub> + 20%He + 500 ppm CO<sub>2</sub>); and (<b>c</b>) Blend 3 (Ar + 1%CO<sub>2</sub> + 1%H<sub>2</sub>) (the black dots represent the indentation positions).</p> Full article ">Figure 12
<p>Schaeffler’s constitutional diagram showing the position of the intercept between Cr<sub>eq</sub> and Ni<sub>eq</sub> of the wire composition (<a href="#materials-17-03328-t003" class="html-table">Table 3</a>).</p> Full article ">Figure 13
<p>Microstructures (500× magnification and etched with aqua regia) of the walls, using as shielding gas: (<b>a</b>) Blend 1 (Ar + 2%CO<sub>2</sub>); (<b>b</b>) Blend 2 (Ar + 2%H<sub>2</sub> + 20%He + 500 ppm CO<sub>2</sub>); (<b>c</b>) Blend 3 (Ar + 1%CO<sub>2</sub> + 1%H<sub>2</sub>) (see positions of them in <a href="#materials-17-03328-f002" class="html-fig">Figure 2</a>).</p> Full article ">Figure 14
<p>Fe–Cr–Ni pseudo-binary diagram, considering 63% (by weight) Fe and Cr<sub>eq</sub> = 22% and Ni<sub>eq</sub> = 13%.</p> Full article ">Figure 15
<p>Ferrite content measured using a Feritscope along the centre of the cross-sections and in the last deposited layer (see referred positions in <a href="#materials-17-03328-f002" class="html-fig">Figure 2</a>).</p> Full article ">
29 pages, 41374 KiB  
Article
Continuous Drive Friction Welded Al/Cu Joints Produced Using Short Welding Time, Elevated Rotational Speed, and High Welding Pressures
by Veljko Milašinović, Ana Alil, Mijat Milašinović, Aleksandar Vencl, Michal Hatala, Stefan Dikić and Bojan Gligorijević
Materials 2024, 17(13), 3284; https://doi.org/10.3390/ma17133284 - 3 Jul 2024
Cited by 1 | Viewed by 1201
Abstract
The present study aimed to enhance the efficiency and efficacy of the Al/Cu joint production process implemented by the company VEMID Ltd., Jagodina, Serbia, by attaining sound joints within a very short welding time. For this purpose, the present study aimed at investigating [...] Read more.
The present study aimed to enhance the efficiency and efficacy of the Al/Cu joint production process implemented by the company VEMID Ltd., Jagodina, Serbia, by attaining sound joints within a very short welding time. For this purpose, the present study aimed at investigating the accuracy and the quality of the continuous drive friction welding (CDFW) process, as well as the optimum combination of CDFW parameters with highest joint efficiency in terms of investigated properties. The accuracy was estimated through an analysis of temperature–time curves recorded during CDFW using an infrared camera. The quality was evaluated through an investigation of the properties of Al/Cu joints produced using different friction (66.7, 88.9, and 133.3 MPa) and forging (88.9, 222.2, and 355.6 MPa) pressures and a constant total welding time (4 s) and rotational speed (2100 rpm). Thermal imaging with an infrared camera demonstrated that the actual total welding time was 15% longer compared to the nominal value. This was attributed to the slow pressure response of the pneumatic brake system. The relative changes in the maximum surface temperature (TMS) during the CDFW process corresponded to changes in welding pressures, indicating the potential of the thermal imaging method for monitoring and assessing this process. A preliminary investigation demonstrated that Al/Cu joints produced using welding pressures less than 88.9 MPa often displayed the presence of non-joined micro-regions at the Al/Cu interface and a significant thickness of interfacial Al2Cu (up to 1 µm). However, when friction pressure was set at 66.7 MPa, an increase in the forging pressure to 222.2 MPa eliminated the presence of non-joined micro-regions and reduced the thickness of Al2Cu to 0.5 µm on the average level. These Al/Cu joints achieved the highest joint efficiencies in terms of strength (100%) and ductility (61%). They exhibited an electrical conductivity higher than 92% of the theoretical value. A further increase in any welding pressure produced similar or deteriorated properties, accompanied by an increase in the consumption of raw materials and energy. Such turn of events was counterproductive to the original goal of increasing the efficiency and efficacy of the CDFW process. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>(<b>a</b>) CDFW experimental setup; (<b>b</b>) shorter Al/Cu rods for local chemical analysis, microstructural examinations, and microhardness measurements; and (<b>c</b>) longer Al/Cu rods for electrical conductivity measurements, tensile testing, and XRPD analysis.</p> Full article ">Figure 2
<p>Polished surfaces of Al/Cu joints for local chemical analysis, microstructural examination, and microhardness measurements.</p> Full article ">Figure 3
<p>Electrical conductivity measurements performed on (<b>a</b>) Al rods, (<b>b</b>) Cu rods, and (<b>c</b>) longer Al/Cu rods; (<b>d</b>) thermal imaging conducted during electrical conductivity measurements.</p> Full article ">Figure 4
<p>(<b>a</b>) Dimensions of Al, Cu, and Al/Cu specimens for tensile testing used in the present study and (<b>b</b>) the appearance of an Al/Cu specimen during tensile testing.</p> Full article ">Figure 5
<p>(<b>a</b>) A1-1, A1-2, and B2-3 Al/Cu specimens with a flat surface fracture; (<b>b</b>) Al/Cu samples and (<b>c</b>) Al and Cu samples for XRPD analysis.</p> Full article ">Figure 6
<p>Variation in the maximum surface temperature with welding time captured with a thermal imaging infrared camera around the Al/Cu interface region of A1, B2, C3, D4, and E5 Al/Cu rods during the CDFW process.</p> Full article ">Figure 7
<p>SEM back-scattering electron images of the outer peripheral regions of (<b>a</b>) A1, (<b>b</b>) B2, (<b>c</b>) C3, (<b>d</b>) D4, and (<b>e</b>) E5 Al/Cu joints. All arrows descriptively indicate the direction and intensity of Al base material flow during the CDFW process.</p> Full article ">Figure 8
<p>Typical EDS point analysis performed in the outer peripheral region of Al/Cu joints. The arrow descriptively indicates the direction of Al base material flow during the CDFW process.</p> Full article ">Figure 9
<p>SEM back-scattering electron images of Al/Cu interfaces taken in the central region of (<b>a</b>) A1, (<b>b</b>) B2, (<b>c</b>) C3, (<b>d</b>) D4, and (<b>e</b>) E5 Al/Cu joints. Green arrows indicate non-joined micro-regions. Blue arrows designate IMC interlayer.</p> Full article ">Figure 10
<p>SEM back-scattering electron images of the Al/Cu interface taken in the inner peripheral region of (<b>a</b>) A1, (<b>b</b>) B2, (<b>c</b>) C3, (<b>d</b>) D4, and (<b>e</b>) E5 Al/Cu joints. Green arrows indicate non-joined micro-regions. Blue arrows designate IMC interlayer. Red arrows show IMC interlayer discontinuity.</p> Full article ">Figure 11
<p>(<b>a</b>) BFLM micrographs of the Al/Cu interface in the central and inner peripheral regions of Al/Cu joints and (<b>b</b>) variation in the IMC interlayer thickness with different CDFW conditions.</p> Full article ">Figure 12
<p>Microhardness at and around the Al/Cu interface in the (<b>a</b>) central and (<b>b</b>) inner peripheral regions of Al/Cu samples.</p> Full article ">Figure 13
<p>(<b>a</b>–<b>d</b>) PLM micrographs of Al samples and (<b>e</b>,<b>f</b>) BFLM micrographs of Cu samples.</p> Full article ">Figure 14
<p>PLM micrographs of CDFW zones in the (<b>a</b>) central and (<b>b</b>) inner peripheral regions on the Al side of Al/Cu samples.</p> Full article ">Figure 15
<p>(<b>a</b>) PLM micrographs of the Al side of Al/Cu samples taken roughly within the 100 µm wide area from the Al/Cu interface and (<b>b</b>) the results of Al grain size measurements within this region.</p> Full article ">Figure 15 Cont.
<p>(<b>a</b>) PLM micrographs of the Al side of Al/Cu samples taken roughly within the 100 µm wide area from the Al/Cu interface and (<b>b</b>) the results of Al grain size measurements within this region.</p> Full article ">Figure 16
<p>Variation in microhardness (<b>a</b>,<b>b</b>) with distance from the Al/Cu interface and (<b>c</b>,<b>d</b>) as a function of the utilized CDFW parameters in the (<b>a</b>,<b>c</b>) central and (<b>b</b>,<b>d</b>) inner peripheral regions on the Al side of Al/Cu samples.</p> Full article ">Figure 17
<p>Variation in microhardness (<b>a</b>,<b>b</b>) with distance from the Al/Cu interface and (<b>c</b>,<b>d</b>) as a function of the utilized CDFW parameters in the (<b>a</b>,<b>c</b>) central and (<b>b</b>,<b>d</b>) inner peripheral region on the Cu side of Al/Cu samples.</p> Full article ">Figure 18
<p>BFLM micrographs of CDFW zones in the central and inner peripheral regions on the Cu side of Al/Cu samples.</p> Full article ">Figure 19
<p>BFLM micrographs of the Cu side of (<b>a</b>) A1, (<b>b</b>) B2, (<b>c</b>) C3, (<b>d</b>) D4, and (<b>e</b>) E5 Al/Cu joints taken in the central region within the 50–100 µm wide area adjacent to the Al/Cu interface. White arrows indicate small equiaxed recrystallized Cu grains. Black arrows depict deformed regions. Orange arrows indicate the DRZ/TMAZ boundary. Green arrows indicate the TMAZ/BM boundary.</p> Full article ">Figure 20
<p>BFLM micrographs of the Cu side of (<b>a</b>) A1, (<b>b</b>) B2, (<b>c</b>) C3, (<b>d</b>) D4, and (<b>e</b>) E5 Al/Cu joints taken in the inner peripheral region within the 50 to 100 µm wide area adjacent to the Al/Cu interface. White arrows indicate small equiaxed recrystallized Cu grains. Black arrows depict deformed regions. Orange arrows indicate the DRZ/TMAZ boundary. Green arrows indicate the TMAZ/BM boundary.</p> Full article ">Figure 21
<p>Electrical conductivities of Al, Cu, and Al/Cu rods obtained by the eddy current method (Al and Cu rods) and by a micro-ohmmeter (Al, Cu, and Al/Cu rods).</p> Full article ">Figure 22
<p>(<b>a</b>) Al and Cu specimens after tensile testing, (<b>b</b>) engineering stress–strain curves obtained during the tensile testing of Al and Cu specimens, (<b>c</b>) tensile strength and elongation at break of Al and Cu, and (<b>d</b>) XRPD analysis of Al and Cu specimens.</p> Full article ">Figure 22 Cont.
<p>(<b>a</b>) Al and Cu specimens after tensile testing, (<b>b</b>) engineering stress–strain curves obtained during the tensile testing of Al and Cu specimens, (<b>c</b>) tensile strength and elongation at break of Al and Cu, and (<b>d</b>) XRPD analysis of Al and Cu specimens.</p> Full article ">Figure 23
<p>(<b>a</b>) Al/Cu specimens after tensile testing; (<b>b</b>–<b>f</b>) engineering stress–strain curves obtained during the tensile testing of (<b>b</b>) A1, (<b>c</b>) B2, (<b>d</b>) C3, (<b>e</b>) D4, and (<b>f</b>) E5 specimens; and (<b>g</b>) the variations in tensile strength and elongation at break with different CDFW process conditions.</p> Full article ">Figure 23 Cont.
<p>(<b>a</b>) Al/Cu specimens after tensile testing; (<b>b</b>–<b>f</b>) engineering stress–strain curves obtained during the tensile testing of (<b>b</b>) A1, (<b>c</b>) B2, (<b>d</b>) C3, (<b>e</b>) D4, and (<b>f</b>) E5 specimens; and (<b>g</b>) the variations in tensile strength and elongation at break with different CDFW process conditions.</p> Full article ">Figure 24
<p>(<b>a</b>) Fractured surface of the B2 Al/Cu specimen; (<b>b</b>) XRPD analysis of the fractured surface after tensile testing. Green arrows indicate fully transferred Al. Yellow arrows designate a thin layer of transferred Al. Red arrows show the absence of transferred Al.</p> Full article ">
10 pages, 2246 KiB  
Article
Enhancement of Abnormal Grain Growth by Surface Quenching Treatment to Eliminate Cu–Cu Bonding Interfaces Using (111)-Oriented Nanotwinned Copper
by Tsan-Feng Lu, Yu-Ting Yen, Yuan-Fu Cheng, Pei-Wen Wang and YewChung Sermon Wu
Materials 2024, 17(13), 3245; https://doi.org/10.3390/ma17133245 - 2 Jul 2024
Viewed by 863
Abstract
Cu–Cu joints have been adopted for ultra-high density of packaging for high-end devices. However, the processing temperature must be kept relatively low, preferably below 300 °C. In this study, a novel surface modification technique, quenching treatment, was applied to achieve Cu-to-Cu direct bonding [...] Read more.
Cu–Cu joints have been adopted for ultra-high density of packaging for high-end devices. However, the processing temperature must be kept relatively low, preferably below 300 °C. In this study, a novel surface modification technique, quenching treatment, was applied to achieve Cu-to-Cu direct bonding using (111)-oriented nanotwinned Cu. The quenching treatment enabled grain growth across the Cu–Cu bonding interface at 275 °C. During quenching treatment, strain energy was induced in the Cu film, resulting in a wrinkled surface morphology. To analyze the strain energy, we utilized an electron backscattered diffraction system to obtain crystallographic information and confirmed it using kernel average misorientation analysis. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>Schematic illustration of the quenching process.</p> Full article ">Figure 2
<p>AFM topography images of: (<b>a</b>) NtCu and (<b>b</b>) QNtCu.</p> Full article ">Figure 3
<p>Plane-view SIM images of (<b>a</b>) NtCu and (<b>b</b>) QNtCu, respectively. SEM images illustrate (<b>c</b>) NtCu and (<b>d</b>) QNtCu at a 52° tilt. Notably, significant wrinkle morphology is evident in (<b>d</b>) following the surface quenching treatment.</p> Full article ">Figure 3 Cont.
<p>Plane-view SIM images of (<b>a</b>) NtCu and (<b>b</b>) QNtCu, respectively. SEM images illustrate (<b>c</b>) NtCu and (<b>d</b>) QNtCu at a 52° tilt. Notably, significant wrinkle morphology is evident in (<b>d</b>) following the surface quenching treatment.</p> Full article ">Figure 4
<p>EBSD KAM maps of (<b>a</b>) NtCu film and (<b>b</b>) QNtCu film. Note: black triangle represents unresolved area.</p> Full article ">Figure 5
<p>Plane-view EBSD OIM images of NtCu and QNtCu films after annealing at 300 °C for various hours. (<b>a</b>–<b>d</b>) NtCu: (<b>a</b>) As deposited, (<b>b</b>) Annealed for 1 h, (<b>c</b>) Annealed for 2 h, and (<b>d</b>) Annealed for 4 h. (<b>e</b>–<b>h</b>) QNtCu: (<b>e</b>) As deposited, (<b>f</b>) Annealed for 1 h, (<b>g</b>) Annealed for 2 h, and (<b>h</b>) Annealed for 4 h. The (111) area ratio is individually marked in each figure.</p> Full article ">Figure 6
<p>Cross-sectional SEM images: Nt/Nt bonded at 275 °C for (<b>a</b>) 2 h, (<b>b</b>) 4 h, (<b>c</b>) 6 h; QNt/Nt bonded at 275 °C for (<b>d</b>) 2 h, (<b>e</b>) 4 h, and (<b>f</b>) 6 h. Note: The orange dashed lines represent the bonding interfaces/IGB in (<b>a</b>–<b>f</b>), while the white arrows point to the sites of triple junctions (TJs), in (<b>b</b>–<b>e</b>). Additionally, the red dashed areas represent AGG in the Cu film in (<b>d</b>–<b>f</b>).</p> Full article ">
11 pages, 9743 KiB  
Article
Effect of Compressive Stress on Copper Bonding Quality and Bonding Mechanisms in Advanced Packaging
by Tsan-Feng Lu, Ping-Yang Lee and YewChung Sermon Wu
Materials 2024, 17(10), 2236; https://doi.org/10.3390/ma17102236 - 9 May 2024
Cited by 1 | Viewed by 1220
Abstract
The thermal expansion behavior of Cu plays a critical role in the bonding mechanism of Cu/SiO2 hybrid joints. In this study, artificial voids, which were observed to evolve using a focused ion beam, were introduced at the bonded interfaces to investigate the [...] Read more.
The thermal expansion behavior of Cu plays a critical role in the bonding mechanism of Cu/SiO2 hybrid joints. In this study, artificial voids, which were observed to evolve using a focused ion beam, were introduced at the bonded interfaces to investigate the influence of compressive stress on bonding quality and mechanisms at elevated temperatures of 250 °C and 300 °C. The evolution of interfacial voids serves as a key indicator for assessing bonding quality. We quantified the bonding fraction and void fraction to characterize the bonding interface and found a notable increase in the bonding fraction and a corresponding decrease in the void fraction with increasing compressive stress levels. This is primarily attributed to the Cu film exhibiting greater creep/elastic deformation under higher compressive stress conditions. Furthermore, these experimental findings are supported by the surface diffusion creep model. Therefore, our study confirms that compressive stress affects the Cu–Cu bonding interface, emphasizing the need to consider the depth of Cu joints during process design. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>Cross-sectional SEM images of the (<b>a</b>) W surface and (<b>b</b>) F surface.</p> Full article ">Figure 2
<p>A schematic illustration of the bonded interface, based on the cross-sectional SEM images of the W and F surfaces.</p> Full article ">Figure 3
<p>AFM topography images of the (<b>a</b>) F surface and (<b>b</b>) W surface.</p> Full article ">Figure 4
<p>Low-magnification, cross-sectional SEM images of samples bonded at 250 °C for 0.5 h (B250t0): (<b>a</b>) M3B250t0, (<b>b</b>) M4B250t0, and (<b>c</b>) M5B250t0. The images reveal a notable increase in bonding fraction with the compressive stress. Note: The dashed arrows represent the interfacial length in (<b>a</b>). The dashed area represents the calculation range of VF in (<b>b</b>). The line represents the value of VH in (<b>c</b>).</p> Full article ">Figure 5
<p>High-magnification, cross-sectional SEM images of samples bonded at 250 °C (B250): (<b>a</b>) M3B250t0, (<b>b</b>) M4B250t0, (<b>c</b>) M5B250t0, (<b>d</b>) M3B250t1, (<b>e</b>) M4B250t1, and (<b>f</b>) M5B250t1. The high-pressure conditions of the M5B250t1 bonding resulted in a significant increase in bonding fraction, followed by the closure of interfacial voids by diffusion flow, forming rounded necks and creating a lenticular shape. Note: The characteristic description of void morphology is shown in (<b>a</b>,<b>f</b>).</p> Full article ">Figure 5 Cont.
<p>High-magnification, cross-sectional SEM images of samples bonded at 250 °C (B250): (<b>a</b>) M3B250t0, (<b>b</b>) M4B250t0, (<b>c</b>) M5B250t0, (<b>d</b>) M3B250t1, (<b>e</b>) M4B250t1, and (<b>f</b>) M5B250t1. The high-pressure conditions of the M5B250t1 bonding resulted in a significant increase in bonding fraction, followed by the closure of interfacial voids by diffusion flow, forming rounded necks and creating a lenticular shape. Note: The characteristic description of void morphology is shown in (<b>a</b>,<b>f</b>).</p> Full article ">Figure 6
<p>(<b>a</b>) Schematic diagram of the cross-section of part of the bonding interface. (<b>b</b>) Top view of part of the bonding interface.</p> Full article ">Figure 7
<p>Cross-sectional SEM images of samples bonded at 300 °C (B300): (<b>a</b>) M3B300t0, (<b>b</b>) M4B300t0, (<b>c</b>) M5B300t0, (<b>d</b>) M3B300t1, (<b>e</b>) M4B300t1, and (<b>f</b>) M5B300t1. Under high-pressure bonding conditions, the void height (VH) decreases as the bonding fraction (BF) increases, leading to a decrease in the influence of creep deformation, and the dominant mechanism transitions to diffusion, which results in the formation of lenticular shapes.</p> Full article ">
13 pages, 13869 KiB  
Article
The Dominant Role of Recrystallization and Grain Growth Behaviors in the Simulated Welding Heat-Affected Zone of High-Mn Steel
by Yangwen Wang, Honghong Wang, Siyuan Peng, Bin Xia and Hai Zhu
Materials 2024, 17(10), 2218; https://doi.org/10.3390/ma17102218 - 8 May 2024
Viewed by 1223
Abstract
Single-pass-welding thermal cycles with different peak temperatures (Tp) were reproduced by a Gleeble 3800 to simulate the heat-affected zone (HAZ) of a Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) high manganese austenitic steel. Then, the effect of Tp on the microstructure and mechanical properties of [...] Read more.
Single-pass-welding thermal cycles with different peak temperatures (Tp) were reproduced by a Gleeble 3800 to simulate the heat-affected zone (HAZ) of a Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) high manganese austenitic steel. Then, the effect of Tp on the microstructure and mechanical properties of the HAZ were investigated. The results indicate that recrystallization and grain growth play dominant roles. Based on this, the HAZ is proposed to categorize into three zones: the recrystallization heat-affected zone (RHAZ) with a Tp of 700~900 °C, the transition heat-affected zone (THAZ) with a Tp of 900~1000 °C, and the coarse grain heat-affected zone (CGHAZ) with a Tp of 1000~1300 °C. The recrystallization fraction was 29~44% in the RHAZ, rapidly increased to 87% in the THAZ, and exceeded 95% in the CGHAZ. The average grain size was 17~19 μm in the RHAZ, slightly increased to 22 μm in the THAZ, and ultimately increased to 37 μm in the CGHAZ. The yield strength in the RHAZ and THAZ was consistent with the change in recrystallization fraction, while in the CGHAZ, it satisfied the Hall–Petch relationship with grain size. In addition, compared with the base material, the Charpy impact absorbed energy at −196 °C decreased by 22% in the RHAZ, but slightly increased in the CGHAZ. This indicates that the theory of fine grain strengthening and toughening is not entirely applicable to the HAZ of the investigated high-Mn steel. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>(<b>a</b>) Processing schematic diagram of the thermal simulation samples. (<b>b</b>) Temperature–time curves during the welding thermal cycle.</p> Full article ">Figure 2
<p>(<b>a</b>) X-ray diffraction pattern and (<b>b</b>) DSC curves of the Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) steel.</p> Full article ">Figure 3
<p>(<b>a</b>) EBSD grain orientation spread (GOS) histogram and (<b>b</b>) corresponding GOS map, (<b>c</b>) inverse pole figure (IPF), and (<b>d</b>) kernel average misorientation (KAM) map of the Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) steel.</p> Full article ">Figure 4
<p>Effect of the peak temperature on (<b>a</b>) the microhardness, (<b>b</b>) yield strength and ultimate tensile strength, (<b>c</b>) the uniform elongation, and (<b>d</b>) the absorbed impact energy at −196 °C of the simulated samples by welding thermal cycle.</p> Full article ">Figure 5
<p>EBSD inverse pole figures (IPF), grain orientation spread (GOS) maps, and kernel average misorientation (KAM) maps of the Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) steel after thermal cycle simulation at 600 °C, 800 °C, 1000 °C, and 1300 °C. Effect of the peak temperature on the average grain size, recrystallized austenite fraction, annealing twin boundary fraction, and average KAM values of the welding thermal cycle simulation samples are summarized.</p> Full article ">Figure 6
<p>TEM images of (<b>a</b>) recrystallized austenite grains with annealing twins and (<b>b</b>) unrecrystallized austenite grains with dislocation cells of the Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) steel after thermal cycle simulation at 800 °C.</p> Full article ">Figure 7
<p>Recrystallized austenite fraction dependence of the yield strength of the Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) steel after thermal cycle simulation at 600 °C, 700 °C, 800 °C, 850 °C, 900 °C, 950 °C, and 1000 °C.</p> Full article ">Figure 8
<p>Grain size dependence of the yield strength of the Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) steel subjected to the welding thermal cycle at the peak temperature of 1100 °C, 1200 °C and 1300 °C.</p> Full article ">Figure 9
<p>Schematic diagram of the heat-affected zone division based on microstructural and mechanical property evolution.</p> Full article ">
12 pages, 40630 KiB  
Article
Interfacial Reactions between Sn-Based Solders and n-Type Bi2(Te,Se)3 Thermoelectric Material
by Chao-Hong Wang, Chun-Wei Chiu and Mei-Hau Li
Materials 2024, 17(9), 2158; https://doi.org/10.3390/ma17092158 - 5 May 2024
Viewed by 1078
Abstract
This study investigated the interfacial reactions between n-type Bi2(Te,Se)3 thermoelectric material, characterized by a highly-oriented (110) plane, and pure Sn and Sn-3.0Ag-0.5Cu (wt.%) solders, respectively. At 250 °C, the liquid-state Sn/Bi2(Te,Se)3 reactions resulted in the formation of [...] Read more.
This study investigated the interfacial reactions between n-type Bi2(Te,Se)3 thermoelectric material, characterized by a highly-oriented (110) plane, and pure Sn and Sn-3.0Ag-0.5Cu (wt.%) solders, respectively. At 250 °C, the liquid-state Sn/Bi2(Te,Se)3 reactions resulted in the formation of both SnTe and BiTe phases, with Bi-rich particles dispersed within the SnTe phase. The growth of the SnTe phase exhibited diffusion-controlled parabolic behavior over time. In contrast, the growth rate was considerably slower compared to that observed with p-type (Bi,Sb)2Te3. Solid-state Sn/Bi2(Te,Se)3 reactions conducted between 160 °C and 200 °C exhibited similar interfacial microstructures. The SnTe phase remained the primary reaction product, embedded with tiny Bi-rich particles, revealing a diffusion-controlled growth. However, the BiTe layer had no significant growth. Further investigation into growth kinetics of intermetallic compounds and microstructural evolution was conducted to elucidate the reaction mechanism. The slower growth rates in Bi2(Te,Se)3, compared to the reactions with (Bi,Sb)2Te3, could be attributed to the strong suppression effect of Se on SnTe growth. Additionally, the interfacial reactions of Bi2(Te,Se)3 with Sn-3.0Ag-0.5Cu were also examined, showing similar growth behavior to those observed with Sn solder. Notably, compared with Ag, Cu tends to diffuse towards the interfacial reaction phases, resulting in a high Cu solubility within the SnTe phase. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>XRD spectra of n-type Bi<sub>2</sub>(Te,Se)<sub>3</sub> thermoelectric material: (<b>a</b>) the commercial bulk material, (<b>b</b>) ground Bi<sub>2</sub>(Te,Se)<sub>3</sub> powders, and (<b>c</b>) schematically illustrating the Bi<sub>2</sub>(Te,Se)<sub>3</sub> substrate with a preferred orientation of (1 1 0).</p> Full article ">Figure 2
<p>BEI micrographs of the Sn/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions at 250 °C for (<b>a</b>) 1 min, (<b>b</b>) 5 min, (<b>c</b>) 10 min, and (<b>d</b>) 30 min.</p> Full article ">Figure 3
<p>The grain morphologies of the SnTe phase in the Sn/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions at 250 °C for (<b>a</b>) 5 min and (<b>b</b>) 30 min.</p> Full article ">Figure 4
<p>IMC growth kinetics analysis of the liquid-state Sn/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions at 250 °C. (<b>a</b>) Average thicknesses of SnTe and BiTe layers as a function of aging time. (<b>b</b>) The plot of average thickness of SnTe versus the square root of reaction time.</p> Full article ">Figure 5
<p>BEI micrographs of the Sn/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions at 180 °C for different durations: (<b>a</b>) the initial interface, (<b>b</b>) 30 min, (<b>c</b>) 6 h, and (<b>d</b>) 24 h.</p> Full article ">Figure 6
<p>BEI micrographs showing the Sn/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions at 200 °C for (<b>a</b>) 30 min and (<b>b</b>) 6 h.</p> Full article ">Figure 7
<p>IMC growth kinetics analysis of the solid-state Sn/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions at 160 °C, 180 °C, and 200 °C. (<b>a</b>) Average thicknesses of SnTe layers as a function of aging time. (<b>b</b>) Average thicknesses of BiTe layers as a function of aging time. (<b>c</b>) The plot of average thickness of SnTe versus the square root of aging time. (<b>d</b>) Arrhenius plot of ln <span class="html-italic">k<sub>diff</sub></span> versus 1000/<span class="html-italic">T</span> for the SnTe growth.</p> Full article ">Figure 8
<p>Schematic illustration of the solid-state Sn/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions: (<b>a</b>) the initial condition, (<b>b</b>) Scenario I, and (<b>c</b>) Scenario II.</p> Full article ">Figure 9
<p>BEI micrographs showing the reactions of solders with various substrates at 180 °C for 6 h: (<b>a</b>) Sn/Te, (<b>b</b>) Sn-1wt.%Sb/Te, (<b>c</b>) Sn-1wt.%Se/Te, (<b>d</b>) Sn/Sb<sub>2</sub>Te<sub>3</sub>, and (<b>e</b>) Sn/Te<sub>4.7</sub>Se<sub>0.3</sub>. In Figure (<b>d</b>), the dashed lines represent the boundaries between SnSb and SnTe, and between SnTe and Sb<sub>2</sub>Te<sub>3</sub>, respectively.</p> Full article ">Figure 10
<p>BEI micrographs of the SAC305/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions, (<b>a</b>–<b>c</b>) at 250 °C for 1 min, 10 min, and 30 min, respectively; (<b>d</b>) at 180 °C for 6 h.</p> Full article ">Figure 11
<p>IMC growth analysis of the liquid-state SAC305/Bi<sub>2</sub>(Te,Se)<sub>3</sub> reactions at 250 °C. (<b>a</b>) Average thicknesses of SnTe and BiTe layers as a function of aging time. (<b>b</b>) The plot of average thickness of SnTe versus the square root of reaction time.</p> Full article ">
10 pages, 3506 KiB  
Article
Effect of Cu Film Thickness on Cu Bonding Quality and Bonding Mechanism
by Tsan-Feng Lu, Kai-Ning Hsu, Ching-Chi Hsu, Chia-Yu Hsu and YewChung Sermon Wu
Materials 2024, 17(9), 2150; https://doi.org/10.3390/ma17092150 - 4 May 2024
Cited by 1 | Viewed by 1277
Abstract
In the hybrid bonding process, the final stage of chemical mechanical polishing plays a critical role. It is essential to ensure that the copper surface is recessed slightly from the oxide surface. However, this recess can lead to the occurrence of interfacial voids [...] Read more.
In the hybrid bonding process, the final stage of chemical mechanical polishing plays a critical role. It is essential to ensure that the copper surface is recessed slightly from the oxide surface. However, this recess can lead to the occurrence of interfacial voids between the bonded copper interfaces. To examine the effects of copper film thickness on bonding quality and bonding mechanisms in this study, artificial voids were intentionally introduced at the bonded interfaces at temperatures of 250 °C and 300 °C. The results revealed that as the thickness of the copper film increases, there is an increase in the bonding fraction and a decrease in the void fraction. The variations in void height with different copper film thicknesses were influenced by the bonding mechanism and bonding fraction. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>Cross-sectional SEM images of the (<b>a</b>) W and (<b>b</b>) F surfaces.</p> Full article ">Figure 2
<p>A schematic illustration of the contacted interface of the W and F surfaces.</p> Full article ">Figure 3
<p>Cross-sectional SEM images of samples bonded at 250 °C: (<b>a</b>) 1B250t0.5, (<b>b</b>) 2B250t0.5, (<b>c</b>) 3B250t0.5, (<b>d</b>) 1B250t1, (<b>e</b>) 2B250t1, and (<b>f</b>) 3B250t1.</p> Full article ">Figure 4
<p>Schematic diagrams of the (<b>a</b>) cross-section and (<b>b</b>) top view of the part of the bonded interface.</p> Full article ">Figure 5
<p>SEM cross-sectional images of samples bonded at 300 °C: (<b>a</b>) 1B300t0.5, (<b>b</b>) 2B300t0.5, (<b>c</b>) 3B300t0.5, (<b>d</b>) 1B300t1, (<b>e</b>) 2B300t1, and (<b>f</b>) 3B300t1.</p> Full article ">Figure 5 Cont.
<p>SEM cross-sectional images of samples bonded at 300 °C: (<b>a</b>) 1B300t0.5, (<b>b</b>) 2B300t0.5, (<b>c</b>) 3B300t0.5, (<b>d</b>) 1B300t1, (<b>e</b>) 2B300t1, and (<b>f</b>) 3B300t1.</p> Full article ">
13 pages, 2779 KiB  
Article
Weldability and Mechanical Properties of Pure Copper Foils Welded by Blue Diode Laser
by Tim Pasang, Shumpei Fujio, Pai-Chen Lin, Yuan Tao, Mao Sudo, Travis Kuendig, Yuji Sato and Masahiro Tsukamoto
Materials 2024, 17(9), 2140; https://doi.org/10.3390/ma17092140 - 2 May 2024
Cited by 2 | Viewed by 1572
Abstract
The need to manufacture components out of copper is significantly increasing, particularly in the solar technology, semiconductor, and electric vehicle sectors. In the past few decades, infrared laser (IR) and green laser (GL) have been the primary technologies used to address this demand, [...] Read more.
The need to manufacture components out of copper is significantly increasing, particularly in the solar technology, semiconductor, and electric vehicle sectors. In the past few decades, infrared laser (IR) and green laser (GL) have been the primary technologies used to address this demand, especially for small or thin components. However, with the increased demand for energy saving, alternative joint techniques such as blue diode laser (BDL) are being actively explored. In this paper, bead-on-plate welding experiments on 0.2 mm thick pure copper samples employing a BDL are presented. Two sets of parameters were carefully selected in this investigation, namely Cu-1: Power (P) = 200 W; Speed (s) = 1 mm/s; and angle = 0°, and Cu-2: P = 200 W; s = 5 mm/s; and angle = 10°. The results from both sets of parameters produced defect-free full penetration welds. Hardness test results indicated relatively softer weld zones compared with the base metal. Tensile test samples fractured in the weld zones. Overall, the samples welded with Cu-1 parameters showed better mechanical properties, such as strength and elongation, than those welded with the Cu-2 parameters. The tensile strength and elongation obtained from Cu-1 were marginally lower than those of the unwelded pure copper. The outcomes from this research provide an alternative welding technique that is able to produce reliable, strong, and precise joints, particularly for small and thin components, which can be very challenging to produce. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>Schematic diagram of the welding process using blue diode laser (BDL) technology at JWRI, Osaka University.</p> Full article ">Figure 2
<p>(<b>a</b>) Schematic diagram of the dog-bone sample with dimensions (in mm). Welded coupons (<b>i</b>) and dog-bone samples (<b>ii</b>) following BDL welding using the parameters of (<b>b</b>) P = 200 W, s = 5 mm/s 10°, and (<b>c</b>) P = 200 W, s = 1 mm/s 0°. Note: (<b>a</b> and <b>i</b>) sample drawings, and (<b>ii</b>) dog-bones and metallographic samples following the wire cutting.</p> Full article ">Figure 3
<p>The absorptivity level of various metals (pure Al, pure Cu, pure Au, and SS316L) on a range of wavelengths using the UV-2600 equipped with ISR-2600 Shimadzu Co. (Shimadzu Corporation, Kyoto, Japan). The approximate wavelengths of infrared (IR), green laser (GL), and blue laser (BL) are indicated.</p> Full article ">Figure 4
<p>Weld profiles of samples welded with (<b>a</b>) Cu-1 and (<b>b</b>) Cu-2 parameters.</p> Full article ">Figure 5
<p>Hardness profiles of both samples, showing low hardness in the weld zones compared with the base metal. HAZ and FZ lines are indicative as they are not very clear on the optical micrographs.</p> Full article ">Figure 6
<p>Stress–strain diagrams from tensile testing representing Cu-1, Cu-2, and unwelded samples.</p> Full article ">Figure 7
<p>Images from digital image correlation (DIC) of welded Cu showing (<b>a</b>) P = 200 W; s = 1 mm/s; 0°, and (<b>b</b>) P = 200 W; s = 5 mm/s; 10°. Note: (<b>i</b>) is the initial stage, (<b>ii</b>) prior to fracture, and (<b>iii</b>) are the fractured samples.</p> Full article ">Figure 8
<p>Macrographs and optical micrographs showing fractured tensile samples. Cu-1 sample fractured in the FZ and, probably, along the HAZ area (<b>a</b>–<b>c</b>), while the Cu-2 sample fractured in the FZ area only (<b>d</b>–<b>f</b>). The blue lines indicate weld zone/BM boundary. Insets: higher magnification micrographs on areas A and B.</p> Full article ">Figure 9
<p>SEM images showing fracture surfaces of sample welded with (<b>a</b>) P = 200 W; s = 1 mm/s; 0°, and (<b>b</b>) P = 200 W; s = 5 mm/s; 10°. Insets: high magnification SEM shows dimples.</p> Full article ">
22 pages, 11055 KiB  
Article
Comparison of the Mechanical Properties of Hardfacings Made by Standard Coated Stick Electrodes and a Newly Developed Rectangular Stick Electrode
by Edvard Bjelajac, Andrej Skumavc, Gorazd Lojen, Mirza Manjgo and Tomaž Vuherer
Materials 2024, 17(9), 2051; https://doi.org/10.3390/ma17092051 - 27 Apr 2024
Cited by 1 | Viewed by 785
Abstract
Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution [...] Read more.
Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution is proposed, which would enable cladding of a larger area with one pass and decrease the dilution rate at the same time—a new type of electrode was developed, exhibiting a rectangular cross-section instead of a round one. Hardfacings, welded with E Fe8 electrodes according to EN 14 700 Standard were welded on mild steel S355 J2 base material with three different coated stick electrodes. The first one was a commercially available, standard, round hardfacing electrode, the second was the same, but with a thinner coating, and the third one was a newly developed rectangular electrode. All three types had equal cross-sections of the metallic core and the same type of coating. Manufacturing of the rectangular electrodes in the laboratory is explained briefly. One- and multi-layer deposits were welded with all three types. Differences were observed in the arc behavior between the round and rectangular electrodes. With the rectangular electrode, the microstructure of the deposit was finer, penetration was shallower, and dilution rates were lower, while the hardness was higher, residual stresses predominantly compressive, and the results of instrumented Charpy impact tests and fracture mechanics tests were better. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>The cross-section of a coated tubular electrode with a seam: 1—coating, 2—metal tube, and 3—powder core [<a href="#B39-materials-17-02051" class="html-bibr">39</a>].</p> Full article ">Figure 2
<p>Method of laboratory production for rectangular coated stick electrode.</p> Full article ">Figure 3
<p>A rectangular coated electrode for SMAW welding.</p> Full article ">Figure 4
<p>Cross-sections of stick coated electrodes: (<b>a</b>) rectangular electrode (PL); (<b>b</b>) round standard electrode with reduced outer diameter (OE); and (<b>c</b>) round standard electrode.</p> Full article ">Figure 5
<p>Geometry of hardfacings: (<b>a</b>) one-layer and (<b>b</b>) two-layer welds, one pass wide; (<b>c</b>) multi-layer welds, two passes wide; (<b>d</b>) multi-layer welds, several passes wide; (<b>e</b>) one-layer weld, several passes wide; and (<b>f</b>) two-layer welds, several passes wide.</p> Full article ">Figure 6
<p>Principle of dilution of the base and filler metals in hardfacing alloys.</p> Full article ">Figure 7
<p>Plan for hardness measurements.</p> Full article ">Figure 8
<p>Geometry of samples for different tests: (<b>a</b>) Charpy specimen; (<b>b</b>) SENB specimen; and (<b>c</b>) sample for residual stress measurements with a stain gauge rosette.</p> Full article ">Figure 9
<p>Residual stress in construction steels: (<b>a</b>) change in <span class="html-italic">R<sub>p</sub></span><sub>02</sub> with temperature <span class="html-italic">T</span>; (<b>b</b>) weld deformation cycle.</p> Full article ">Figure 10
<p>SMAW arc taken by high-speed camera: (<b>a</b>) rectangular stick electrode (∅1 × 12.56 mm); the arc was traveling from one side to the other and back (yellow arrows); (<b>b</b>) thinned round electrode (∅4/∅6.90 mm); and (<b>c</b>) conventional round-shaped electrode (∅4/∅7.85 mm); the arc stays at the same position (yellow points).</p> Full article ">Figure 11
<p>(<b>a</b>) The arc burns where the distance to weld pool is the shortest; (<b>b</b>–<b>d</b>) as the electrode melts, in the search for the shortest distance to the weld pool, the arc traveles from one edge of the electrode to the other; (<b>e</b>) then the journey back starts; the frequency of the journeys, approx. 3.5–4.5-times per second, was determined from the high-speed-camera videos.</p> Full article ">Figure 12
<p>Welding speed and arc-travel speed: (<b>a</b>) in the case of the round electrode; (<b>b</b>) in the case of the rectangular electrode.</p> Full article ">Figure 13
<p>Macro-sections of hardfacing welds: (<b>a</b>,<b>b</b>) represent the rectangular coated stick electrode; (<b>c</b>,<b>d</b>) represent the round thin-coated electrode (∅4/∅6.90 mm); and (<b>e</b>,<b>f</b>) represent the conventional round coated electrode (∅4/∅7.85 mm).</p> Full article ">Figure 14
<p>Microstructure of hardfacing welds: (<b>a</b>,<b>b</b>) HAZ and WM welded by the rectangular coated stick electrode; (<b>c</b>,<b>d</b>) HAZ and WM welded by the round thin-coated electrode (∅4/∅6.90 mm); (<b>e</b>,<b>f</b>) HAZ and WM welded by the standard round coated electrode (∅4/∅7.85 mm); and (<b>g</b>) base material.</p> Full article ">Figure 15
<p>Results of the hardness measurements on welds made with the rectangular stick electrode (∅1 × 12.56 mm): (<b>a</b>) in the vertical direction; (<b>b</b>) in the horizontal direction.</p> Full article ">Figure 16
<p>Results of hardness measurements on welds made with the thin-coated electrode (∅4/∅6.90 mm): (<b>a</b>) in the vertical direction; (<b>b</b>) in the horizontal direction.</p> Full article ">Figure 17
<p>Results of the hardness measurements on welds made with the conventional coated electrode (∅4/∅7.85 mm): (<b>a</b>) in the vertical direction; (<b>b</b>) in the horizontal direction.</p> Full article ">Figure 18
<p>Results of instrumented Charpy tests: (<b>a</b>) rectangular stick electrode (∅1 × 12.56 mm); (<b>b</b>) thinned round electrode (∅4/∅6.90 mm); (<b>c</b>) conventional round electrode (∅4/∅7.85 mm); and (<b>d</b>) base material.</p> Full article ">Figure 19
<p>Results of fracture mechanics tests: (<b>a</b>) force-<span class="html-italic">CMOD</span> diagram; (<b>b</b>) resistance curves <span class="html-italic">J</span>-Δ<span class="html-italic">a</span>.</p> Full article ">Figure 20
<p>Results of fracture mechanics tests: critical <span class="html-italic">J<sub>IC</sub></span> an <span class="html-italic">K<sub>JIC</sub></span>.</p> Full article ">Figure 21
<p>Fractured surfaces of weld metal welded by: (<b>a</b>) a rectangular stick electrode (∅1 × 12.56 mm); (<b>b</b>) a thinned round electrode (∅4/∅6.90 mm); (<b>c</b>) a conventional round electrode (∅4/∅7.85 mm).</p> Full article ">Figure 22
<p>Fracture surfaces of weld metal from SEM in the area of crack incitation and stable crack growth: (<b>a</b>,<b>b</b>) rectangular stick electrode (∅1 × 12.56 mm); (<b>c</b>,<b>d</b>) thinned round electrode (∅4/∅6.90 mm); and (<b>e</b>,<b>f</b>) conventional round electrode (∅4/∅7.85 mm).</p> Full article ">Figure 23
<p>Results of the residual stress measurements. Strains measured with a three-elemental strain-gauge rosette on hardfacings welded by: (<b>a</b>) a rectangular stick electrode (∅1 × 12.56 mm); (<b>b</b>) a conventional round electrode (∅4/∅7.85 mm).</p> Full article ">Figure 24
<p>Residual stresses in hardfacings welded by: (<b>a</b>) a rectangular stick electrode (∅1 × 12.56 mm); (<b>b</b>) a conventional round electrode (∅4/∅7.85 mm).</p> Full article ">
16 pages, 5925 KiB  
Article
Microstructure and Mechanical Properties of Ti-6Al-4V Welds Produced with Different Processes
by Sakari Tolvanen, Robert Pederson and Uta Klement
Materials 2024, 17(4), 782; https://doi.org/10.3390/ma17040782 - 6 Feb 2024
Cited by 3 | Viewed by 1293
Abstract
The effect of defects and microstructure on the mechanical properties of Ti-6Al-4V welds produced by tungsten inert gas welding; plasma arc welding; electron beam welding; and laser beam welding was studied in the present work. The mechanical properties of different weld types were [...] Read more.
The effect of defects and microstructure on the mechanical properties of Ti-6Al-4V welds produced by tungsten inert gas welding; plasma arc welding; electron beam welding; and laser beam welding was studied in the present work. The mechanical properties of different weld types were evaluated with respect to micro hardness; yield strength; ultimate tensile strength; ductility; and fatigue at room temperature and at elevated temperatures (200 °C and 250 °C). Metallographic investigation was carried out to characterize the microstructures of different weld types, and fractographic investigation was conducted to relate the effect of defects on fatigue performance. Electron and laser beam welding produced welds with finer microstructure, higher tensile ductility, and better fatigue performance than tungsten inert gas welding and plasma arc welding. Large pores, and pores located close to the specimen surface, were found to be most detrimental to fatigue life. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>Schematic drawings and dimensions of the samples used for mechanical testing. Tensile and LCF type 1 specimens were perpendicular to the weld zone, and the LCF type 2 specimen was parallel to the weld zone.</p> Full article ">Figure 2
<p>Optical micrographs showing the weld cross sections for (<b>a</b>) TIG, (<b>b</b>) PAW, (<b>c</b>) EBW, and (<b>d</b>) LBW welds in 4 mm thick Ti-64 sheet material.</p> Full article ">Figure 3
<p>Optical micrographs of (<b>a</b>) TIG, (<b>b</b>) PAW, (<b>c</b>) EBW, and (<b>d</b>) LBW welds, and (<b>e</b>) SEM micrograph of PAW weld. The different magnifications can be noticed.</p> Full article ">Figure 4
<p>EPMA line scan across a TIG weld showing the distribution of aluminium and oxygen across the weld, i.e., in the base material, the heat affected zone, and the fusion zone.</p> Full article ">Figure 5
<p>Microhardness profiles across welds produced by EBW, LBW, TIG and PAW after post weld heat treatment.</p> Full article ">Figure 6
<p>Room-temperature tensile tested weld samples. Etched side views and fracture surfaces of (<b>a</b>,<b>b</b>) EBW, (<b>c</b>,<b>d</b>) LBW, and (<b>e</b>,<b>f</b>) PAW.</p> Full article ">Figure 7
<p>LCF results (<b>a</b>) for welds produced by TIG, PAW, EBW, and LBW at 250 °C; (<b>b</b>) EBW and TIG at room temperature; and (<b>c</b>) the effect of weld geometry in LBW. In (<b>a</b>,<b>b</b>), the shape of the symbol indicates the welding process, and the fill of the symbol indicates the type of initiation.</p> Full article ">Figure 8
<p>Optical micrograph of LBW showing the weld geometry. Typical crack initiation site at the weld toe on the root side indicated.</p> Full article ">Figure 9
<p>Fatigue fracture surfaces showing different types of crack initiation sites: (<b>a</b>) a small pore close to surface (EBW); (<b>b</b>) a large internal pore (TIG); (<b>c</b>) initiations at surface and at a cluster of pores (LBW); and (<b>d</b>) a surface initiation site with a facet (EBW).</p> Full article ">Figure 10
<p>The sizes and location of pores initiating fatigue cracks.</p> Full article ">Figure 11
<p>TIG welded LCF specimen investigated with XRM: (<b>a</b>) overview of the fractured LCF specimen; (<b>b</b>) SEM fractograph of pore 1, which initiated the fatigue crack that led to failure of the TIG welded LCF specimen; (<b>c</b>) XRM virtual slice of the surface-breaking pore 2, with a diameter of 136 µm, which initiated a 300–400 μm long microcrack; and (<b>d</b>) XRM virtual slice of pore 3 which did not initiate a crack.</p> Full article ">Figure 12
<p>XRM 3D volume rendering showing distribution of porosity in a fatigue tested, but not fractured, LCF specimen produced by LBW: (<b>a</b>) overview of the LCF specimen, (<b>b</b>) view from top of the weld, x-y-plane, and (<b>c</b>) view from the side of the weld, y-z-plane.</p> Full article ">
13 pages, 12227 KiB  
Article
Microstructure and Mechanical Properties of the Joints from Coarse- and Ultrafine-Grained Al-Mg-Si Alloy Obtained via Friction Stir Welding
by Marta Lipińska
Materials 2023, 16(18), 6287; https://doi.org/10.3390/ma16186287 - 19 Sep 2023
Viewed by 1072
Abstract
In the present study, the welding of coarse- (CG) and ultrafine-grained (UFG) Al-Mg-Si alloy using friction stir welding (FSW) was attempted. The purpose of welding the UFG material was to check the possibility of applying FSW to materials with a thermally unstable microstructure, [...] Read more.
In the present study, the welding of coarse- (CG) and ultrafine-grained (UFG) Al-Mg-Si alloy using friction stir welding (FSW) was attempted. The purpose of welding the UFG material was to check the possibility of applying FSW to materials with a thermally unstable microstructure, which is achieved by severe plastic deformation. This group of materials has significant potential due to the enhanced mechanical properties as a result of the elevated number of structural defects. The CG sample was also examined in order to assess whether there is an influence of the base material microstructure on the weld microstructure and properties. To refine the microstructure, incremental equal channel angular pressing was used. Plastic deformation resulted in grain refinement from 23 µm to 1.5 µm. It caused an increase in the microhardness from 105 HV0.1 to 125 HV0.1 and the tensile strength from 320 MPa to 394 MPa. Similar welds obtained using an FSW method exhibited good quality and grain size in a stir zone of 5 µm. For both welds, a decrease in the microhardness occurred in the stir zone. However, for the weld of UFG Al-Mg-Si, the microhardness distribution was homogeneous, while for the weld of the CG, it was inhomogeneous, which was caused by different characteristics of the second-phase precipitates. The tensile strength of the welds was lowered and equaled 269 MPa and 220 MPa for the CG and UFG welds, respectively. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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<p>Macrographs of the (<b>a</b>) CG and (<b>b</b>) UFG welds (on the left—retreating side; on the right—advancing side).</p> Full article ">Figure 2
<p>EBSD OIM of the (<b>a</b>) CG BM, (<b>b</b>) CG SZ, (<b>c</b>) UFG BM, and (<b>d</b>) UFG SZ.</p> Full article ">Figure 3
<p>Graphs of (<b>a</b>) misorientation angle distribution and (<b>b</b>) GND density.</p> Full article ">Figure 4
<p>PF of the (<b>a</b>) CG BM (square—cube texture; star—Goss texture), (<b>b</b>) CG SZ (with marked identified shear components), (<b>c</b>) UFG BM, and (<b>d</b>) UFG SZ of the welds.</p> Full article ">Figure 5
<p>The TEM micrographs of the (<b>a</b>) BM (β″ precipitates), (<b>b</b>) HAZ (β″ precipitates), (<b>c</b>) SZ (lack of precipitates), and (<b>d</b>) SZ (β’ and β precipitates) of the weld from CG Al-Mg-Si alloy.</p> Full article ">Figure 6
<p>The TEM micrographs of the (<b>a</b>) BM (β″ precipitates), (<b>b</b>) HAZ (β″ precipitates—dissolving), and (<b>c</b>,<b>d</b>) SZ of the weld from UFG Al-Mg-Si alloy.</p> Full article ">Figure 6 Cont.
<p>The TEM micrographs of the (<b>a</b>) BM (β″ precipitates), (<b>b</b>) HAZ (β″ precipitates—dissolving), and (<b>c</b>,<b>d</b>) SZ of the weld from UFG Al-Mg-Si alloy.</p> Full article ">Figure 7
<p>Microhardness maps of the cross section of the welds from (<b>a</b>) CG and (<b>b</b>) UFG Al-Mg-Si.</p> Full article ">Figure 8
<p>Representative stress–strain curves for the welds and base materials.</p> Full article ">Figure 9
<p>DIC maps of the welds from (<b>a</b>) CG and (<b>b</b>) UFG Al-Mg-Si alloy.</p> Full article ">
15 pages, 5661 KiB  
Article
Ni-Al Bronze in Molten Carbonate Manufactured by LPBF: Effect of Porosity Design on Mechanical Properties and Oxidation
by Camila Arcos, Carolina Guerra, Jorge A. Ramos-Grez and Mamié Sancy
Materials 2023, 16(10), 3893; https://doi.org/10.3390/ma16103893 - 22 May 2023
Cited by 3 | Viewed by 1743
Abstract
Fuel cell technology has developed due to diminishing dependence on fossil fuels and carbon footprint production. This work focuses on a nickel–aluminum bronze alloy as an anode produced by additive manufacturing as bulk and porous samples, studying the effect of designed porosity and [...] Read more.
Fuel cell technology has developed due to diminishing dependence on fossil fuels and carbon footprint production. This work focuses on a nickel–aluminum bronze alloy as an anode produced by additive manufacturing as bulk and porous samples, studying the effect of designed porosity and thermal treatment on mechanical and chemical stability in molten carbonate (Li2CO3-K2CO3). Micrographs showed a typical morphology of the martensite phase for all samples in as-built conditions and a spheroid structure on the surface after the heat treatment, possibly revealing the formation of molten salt deposits and corrosion products. FE-SEM analysis of the bulk samples showed some pores with a diameter near 2–5 μm in the as-built condition, which varied between 100 and −1000 μm for the porous samples. After exposure, the cross-section images of porous samples revealed a film composed principally of Cu and Fe, Al, followed by a Ni-rich zone, whose thickness was approximately 1.5 µm, which depended on the porous design but was not influenced significantly by the heat treatment. Additionally, by incorporating porosity, the corrosion rate of NAB samples increased slightly. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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Figure 1
<p>Micrographs of (<b>a</b>) bulk, (<b>b</b>,<b>d</b>) gyroid with wall structure, and (<b>c</b>,<b>e</b>) gyroid structure. Samples (<b>b</b>,<b>c</b>) without and (<b>d</b>,<b>e</b>) with thermal treatment.</p> Full article ">Figure 2
<p>FE-SEM images of (<b>a</b>,<b>f</b>) bulk, (<b>b</b>,<b>d</b>,<b>g</b>,<b>i</b>) gyroid with wall structure, and (<b>c</b>,<b>e</b>,<b>h</b>,<b>j</b>) gyroid structure (<b>a</b>–<b>e</b>) before and (<b>f</b>–<b>j</b>) after exposure to molten salt. Samples (<b>a</b>–<b>c</b>,<b>f</b>–<b>h</b>) without and (<b>d</b>,<b>e</b>,<b>i</b>,<b>j</b>) with thermal treatment.</p> Full article ">Figure 3
<p>EDS surface mapping of (<b>a</b>,<b>f</b>) bulk, (<b>b</b>,<b>d</b>,<b>g</b>,<b>i</b>) gyroid with wall structure, and (<b>c</b>,<b>e</b>,<b>h</b>,<b>j</b>) gyroid structure, (<b>a</b>–<b>e</b>) before and (<b>f</b>–<b>j</b>) after exposure to molten salt. Samples (<b>a</b>–<b>c</b>,<b>f</b>–<b>h</b>) without and (<b>d</b>–<b>e</b>,<b>i</b>–<b>j</b>) with thermal treatment.</p> Full article ">Figure 4
<p>(<b>a</b>–<b>d</b>) FE-SEM and (<b>e</b>–<b>h</b>) EDS analysis of the cross-section of (<b>a</b>,<b>b</b>) gyroid with wall structure and (<b>c</b>,<b>d</b>) gyroid structure after 21 days of exposure to molten salt. Samples (<b>a</b>,<b>b</b>) without and (<b>c</b>,<b>d</b>) with heat treatment.</p> Full article ">Figure 5
<p>GD-OES of bulk samples (<b>a</b>) before and (<b>b</b>) after 21 days of exposure to molten salt. (<span style="color:red">--</span>) O, (<span style="color:#2DD3EF">--</span>) Al, (<span style="color:#133EDB">--</span>) Fe, (<span style="color:#41DB35">--</span>) Ni, and (<span style="color:#F89E0C">--</span>) Cu.</p> Full article ">Figure 6
<p>XRD patterns of the bulk sample in as-built condition and after heat treatment (HT).</p> Full article ">Figure 7
<p>Microhardness (HV) of the samples before exposure.</p> Full article ">Figure 8
<p>Compression stress–strain curves of (<b>a</b>) bulk, (<b>b</b>,<b>d</b>) gyroid with wall structure, and (<b>c</b>,<b>e</b>) gyroid structure. Samples with “empty symbols” before and with “filled symbols” after 21 days of exposure to molten salt.</p> Full article ">Figure 9
<p>The variation of weight (<b>a</b>) and corrosion rate of samples (<b>b</b>) after 21 days (504 h) of exposure to molten salt. The samples exposed are <span class="html-fig-inline" id="materials-16-03893-i004"><img alt="Materials 16 03893 i004" src="/materials/materials-16-03893/article_deploy/html/images/materials-16-03893-i004.png"/></span>.</p> Full article ">Figure 10
<p>Physical model of the corrosion product evolution as a function of exposure time in molten salt at 550 °C in aerated conditions.</p> Full article ">Figure 11
<p>XPS survey of sample in as-built condition and heat treated before and after exposure. (<b>a</b>) Al, (<b>b</b>) Fe, and (<b>c</b>) Cu.</p> Full article ">
12 pages, 7663 KiB  
Article
The Influence of MSR-B Mg Alloy Surface Preparation on Bonding Properties
by Katarzyna Łyczkowska, Damian Miara, Beata Rams, Janusz Adamiec and Katarzyna Baluch
Materials 2023, 16(10), 3887; https://doi.org/10.3390/ma16103887 - 22 May 2023
Cited by 3 | Viewed by 1561
Abstract
Nowadays, industrial adhesives are replacing conventional bonding methods in many industries, including the automotive, aviation, and power industries, among others. The continuous development of joining technology has promoted adhesive bonding as one of the basic methods of joining metal materials. This article presents [...] Read more.
Nowadays, industrial adhesives are replacing conventional bonding methods in many industries, including the automotive, aviation, and power industries, among others. The continuous development of joining technology has promoted adhesive bonding as one of the basic methods of joining metal materials. This article presents the influence of surface preparation of magnesium alloys on the strength properties of a single-lap adhesive joint using a one-component epoxy adhesive. The samples were subjected to shear strength tests and metallographic observations. The lowest properties of the adhesive joint were obtained on samples degreased with isopropyl alcohol. The lack of surface treatment before joining led to destruction by adhesive and mixed mechanisms. Higher properties were obtained for samples ground with sandpaper. The depressions created as a result of grinding increased the contact area of the adhesive with the magnesium alloys. The highest properties were noticed for samples after sandblasting. This proved that the development of the surface layer and the formation of larger grooves increased both the shear strength and the resistance of the adhesive bonding to fracture toughness. It was found that the method of surface preparation had a significant influence on the resulting failure mechanism, and the adhesive bonding of the casting of magnesium alloy QE22 can be used successfully. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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Figure 1
<p>Examples of cohesive and adhesive failures [<a href="#B65-materials-16-03887" class="html-bibr">65</a>].</p> Full article ">Figure 2
<p>The scheme of joint used in the static shear test, mm.</p> Full article ">Figure 3
<p>The profilograph measurements of Mg alloy surface after cleaning (<b>a</b>), grinding (<b>b</b>), and abrasive blasting (<b>c</b>).</p> Full article ">Figure 4
<p>Microstructure of the adhesively bonded joints of MSR-B Mg alloy samples after pre-treatment with (<b>a</b>,<b>d</b>) isopropyl alcohol, (<b>b</b>,<b>e</b>) grinding with sandpaper 120 μm, or (<b>c</b>,<b>f</b>) abrasive blasting.</p> Full article ">Figure 4 Cont.
<p>Microstructure of the adhesively bonded joints of MSR-B Mg alloy samples after pre-treatment with (<b>a</b>,<b>d</b>) isopropyl alcohol, (<b>b</b>,<b>e</b>) grinding with sandpaper 120 μm, or (<b>c</b>,<b>f</b>) abrasive blasting.</p> Full article ">Figure 5
<p>The macrostructure and morphologies of MSR-B alloy samples after pre-treatment with (<b>a</b>) isopropyl alcohol, (<b>b</b>) grinding with 120 μm, or (<b>c</b>) abrasive blasting with corundum.</p> Full article ">Figure 6
<p>Shear strength of the adhesive-bonded joints in relation to pre-adhesive bonding surface preparation (sample dimension of 25 × 100 × 3 mm).</p> Full article ">Figure 7
<p>Effect of surface treatment on the fractography of the adhesive-bonded lap shear. (<b>a</b>–<b>c</b>) samples with 25 × 100 × 1.6; 12.5 mm, (<b>d</b>–<b>f</b>) samples with 25 × 100 × 3.0; 6.0 mm.</p> Full article ">Figure 8
<p>The surfaces of the samples after treatment, SEM. (<b>a</b>,<b>d</b>) visible delaminations in adhesive layer with reinforcing particles, (<b>b</b>,<b>e</b>) numerous scratches filled with adhesive and numerous reinforcing particles, (<b>c</b>,<b>f</b>) air bubbles and gas pores in adhesive layer after sandblasting.</p> Full article ">
20 pages, 10818 KiB  
Article
Influence of Microstructure and Mechanical Properties of Dissimilar Rotary Friction Welded Inconel to Stainless Steel Joints
by Akhil Reddy Beeravolu, Nagumothu Kishore Babu, Mahesh Kumar Talari, Ateekh Ur Rehman and Prakash Srirangam
Materials 2023, 16(8), 3049; https://doi.org/10.3390/ma16083049 - 12 Apr 2023
Cited by 5 | Viewed by 2139
Abstract
The present study aims to evaluate the microstructure, grain size, and mechanical properties of the dissimilar AISI 316L/Inconel 718 (IN 718) rotary friction welded joints under both the as-welded and post-weld heat treatment (PWHT) conditions. Because of reduced flow strength at elevated temperatures, [...] Read more.
The present study aims to evaluate the microstructure, grain size, and mechanical properties of the dissimilar AISI 316L/Inconel 718 (IN 718) rotary friction welded joints under both the as-welded and post-weld heat treatment (PWHT) conditions. Because of reduced flow strength at elevated temperatures, the AISI 316L and IN 718 dissimilar weldments exhibited more flash formation on the AISI 316L side. At higher rotating speeds during friction welding, an intermixing zone was created at the weld joint interface due to the material softening and squeezing. The dissimilar welds exhibited distinctive regions, including the fully deformed zone (FDZ), heat-affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and the base metal (BM), located on either side of the weld interface. The dissimilar friction welds, AISI 316L/IN 718 ST and AISI 316L/IN 718 STA, exhibited yield strength (YS) of 634 ± 9 MPa and 602 ± 3 MPa, ultimate tensile strength (UTS) of 728 ± 7 MPa and 697± 2 MPa, and % elongation (% El) of 14 ± 1.5 and 17 ± 0.9, respectively. Among the welded samples, PWHT samples exhibited high strength (YS = 730 ± 2 MPa, UTS = 828 ± 5 MPa, % El = 9 ± 1.2), and this may be attributed to the formation of precipitates. Dissimilar PWHT friction weld samples resulted in the highest hardness among all the conditions in the FDZ due to the formation of precipitates. On the AISI 316L side, prolonged exposure to high temperatures during PWHT resulted in grain growth and decreased hardness. During the tensile test at ambient temperature, both the as-welded and PWHT friction weld joints failed in the HAZ regions of the AISI 316L side. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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Figure 1

Figure 1
<p>Rotary friction welding setup used to weld-dissimilar AISI 316L/IN 718 combinations.</p> Full article ">Figure 2
<p>Optical micrographs of (<b>a</b>) AISI 316L, (<b>b</b>) Inconel 718 ST, and (<b>c</b>) Inconel 718 STA base metals.</p> Full article ">Figure 2 Cont.
<p>Optical micrographs of (<b>a</b>) AISI 316L, (<b>b</b>) Inconel 718 ST, and (<b>c</b>) Inconel 718 STA base metals.</p> Full article ">Figure 3
<p>Scanning electron micrographs and EDS analysis of the precipitates in (<b>a</b>,<b>b</b>) Inconel 718 ST and (<b>c</b>,<b>d</b>) Inconel 718 STA base metals, respectively.</p> Full article ">Figure 3 Cont.
<p>Scanning electron micrographs and EDS analysis of the precipitates in (<b>a</b>,<b>b</b>) Inconel 718 ST and (<b>c</b>,<b>d</b>) Inconel 718 STA base metals, respectively.</p> Full article ">Figure 3 Cont.
<p>Scanning electron micrographs and EDS analysis of the precipitates in (<b>a</b>,<b>b</b>) Inconel 718 ST and (<b>c</b>,<b>d</b>) Inconel 718 STA base metals, respectively.</p> Full article ">Figure 4
<p>Macrograph and visual view of dissimilar friction welds AISI 316L/IN 718 ST (<b>a</b>,<b>c</b>) and AISI 316L/IN 718 STA (<b>b</b>,<b>d</b>).</p> Full article ">Figure 5
<p>Cross-sectional view of weld joint interface of dissimilar friction weld AISI 316L-IN718 ST condition (<b>a</b>) weld interface; (<b>b</b>) base metal on AISI 316L side; (<b>c</b>) HAZ on AISI 316L side; (<b>d</b>) TMAZ on AISI 316L side; (<b>e</b>) FDZ on AISI 316L side; (<b>f</b>) FDZ on IN718 side; (<b>g</b>) TMAZ on IN718 side; (<b>h</b>) HAZ on IN718 side; and (<b>i</b>) base metal on IN718 side.</p> Full article ">Figure 6
<p>Cross-sectional view of weld joint interface of dissimilar friction weld AISI 316L-IN718 STA condition: (<b>a</b>) weld interface; (<b>b</b>) base metal on AISI 316L side; (<b>c</b>) HAZ on AISI 316L side; (<b>d</b>) TMAZ on AISI 316L side; (<b>e</b>) FDZ on AISI 316L side; (<b>f</b>) FDZ on IN718 side; (<b>g</b>) TMAZ on IN718 side; (<b>h</b>) HAZ on IN718 side; and (<b>i</b>) base metal on IN718 side.</p> Full article ">Figure 7
<p>Scanning electron micrograph of dissimilar friction welds (<b>a</b>) AISI316L/IN718 ST and (<b>b</b>) AISI316/-IN718 STA.</p> Full article ">Figure 8
<p>SEM micrograph of dissimilar friction welds (<b>a</b>) AISI316L-IN718 ST with EDS line scan and (<b>b</b>) AISI316L-IN718 STA with EDS line scan.</p> Full article ">Figure 9
<p>Cross-sectional view of weld joint interface of dissimilar friction weld AISI 316L-IN718 PWHT condition (<b>a</b>) weld interface; (<b>b</b>) base metal on AISI 316L side; (<b>c</b>) HAZ on AISI 316L side; (<b>d</b>) TMAZ on AISI 316L side; (<b>e</b>) FDZ on AISI 316L side; (<b>f</b>) FDZ on IN718 side; (<b>g</b>) TMAZ on IN718 side; (<b>h</b>) HAZ on IN718 side; and (<b>i</b>) base metal on IN718 side.</p> Full article ">Figure 10
<p>The microhardness distribution across the weld interface of dissimilar friction welds AISI316L-IN718 ST, AISI316L-IN718 STA, and PWHT.</p> Full article ">Figure 11
<p>Typical tensile curves of parent metals and friction welded joints.</p> Full article ">Figure 12
<p>Tensile failure location of the dissimilar friction welds (<b>a</b>) AISI 316L-IN718 ST and (<b>b</b>) AISI 316L-IN718 STA and (<b>c</b>) PWHT.</p> Full article ">Figure 13
<p>Tensile fracture morphology of dissimilar friction welds (<b>a</b>) AISI316L/IN718 ST, (<b>b</b>) AISI316/-IN718 STA, and (<b>c</b>) PWHT.</p> Full article ">
19 pages, 7623 KiB  
Article
Effect of Heat Treatment on the Microstructure and Mechanical Properties of Rotary Friction Welded AA7075 and AA5083 Dissimilar Joint
by Aditya M. Mahajan, Nagumothu Kishore Babu, Mahesh Kumar Talari, Ateekh Ur Rehman and Prakash Srirangam
Materials 2023, 16(6), 2464; https://doi.org/10.3390/ma16062464 - 20 Mar 2023
Cited by 6 | Viewed by 1719
Abstract
The present work aims to investigate the changes in the microstructural and mechanical properties of various pre- and post weld heat treatments (PWHTs) on rotary friction welded dissimilar (AA7075 and AA5083) aluminum alloys. The investigation focused on the evolution of weld macro- and [...] Read more.
The present work aims to investigate the changes in the microstructural and mechanical properties of various pre- and post weld heat treatments (PWHTs) on rotary friction welded dissimilar (AA7075 and AA5083) aluminum alloys. The investigation focused on the evolution of weld macro- and microstructures, as well as the changes in hardness and tensile properties resulting from friction welding. The joint integrity was studied through various characterization techniques, and no cracks or incomplete bonding was observed. The study found that the dissimilar joints of the AA7075 and AA5083 alloys displayed higher flash formation on the AA7075 side, which has a lower melting temperature compared to the AA5083 alloy. Various zones were identified in the weld region, including the dynamic recrystallized zone (DRZ), the thermomechanically affected zone (TMAZ) consisting of TMAZ-1 (elongated grains) and TMAZ-2 (compressed/distorted grains), the heat-affected zone (HAZ), and the base metal (BM) zone. The rotary friction welded sample AA5083/AA7075-PWHT joint exhibited the highest strength (yield strength (YS): 195 ± 3 MPa, ultimate tensile strength (UTS): 387 ± 2 MPa) among all the other welded conditions, and this may be attributed to the major strengthening precipitates MgZn2 (of AA7075) formed during postweld aging. All dissimilar welds failed in the HAZ region of the AA5083 side due to the formation of coarse grains, indicating the weakest region. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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Figure 1

Figure 1
<p>Rotary friction welding setup.</p> Full article ">Figure 2
<p>Tensile sample prepared as per ASTM standards.</p> Full article ">Figure 3
<p>Optical micrographs along the transverse and longitudinal to the axis of the base alloy rods in AA7075-STA (<b>a</b>,<b>b</b>), AA7075-ST (<b>c</b>,<b>d</b>), and AA5083 (<b>e</b>,<b>f</b>).</p> Full article ">Figure 4
<p>SEM image and EDS analysis of the AA7075-ST (Base).</p> Full article ">Figure 5
<p>Visual view of welded joints (<b>a</b>) AA5083/AA7075-STA and (<b>b</b>) AA5083/AA7075-ST.</p> Full article ">Figure 6
<p>Macrographs of the weldment (<b>a</b>) AA5083/AA7075-STA and (<b>b</b>) AA5083/AA7075-ST.</p> Full article ">Figure 7
<p>Microstructure across the weld interface of AA5083/AA7075-STA. AA7075 side: (<b>a</b>) TMAZ-1, (<b>b</b>) TMAZ-2, (<b>c</b>) HAZ, (<b>d</b>) base metal; AA5083 side: (<b>e</b>) HAZ, (<b>f</b>) TMAZ-2, (<b>g</b>) TMAZ-1, (<b>h</b>) DRZ.</p> Full article ">Figure 8
<p>Optical microstructure at the DRZ of AA5083/AA7075-STA welds.</p> Full article ">Figure 9
<p>Microstructure across the weld interface of AA5083/AA7075-ST. AA7075 side: (<b>a</b>) TMAZ-1, (<b>b</b>) TMAZ-2, (<b>c</b>) HAZ, (<b>d</b>) base metal; AA5083 side: (<b>e</b>) HAZ, (<b>f</b>) TMAZ-2, (<b>g</b>) TMAZ-1, (<b>h</b>) DRZ.</p> Full article ">Figure 10
<p>Average grain size variation across different weld zones of AA5083/AA7075 welds.</p> Full article ">Figure 11
<p>EDS (line scan) microanalysis: elemental distribution across weld interface (<b>a</b>) AA5083/AA7075-STA, (<b>b</b>) AA5083/AA7075-ST, and (<b>c</b>) AA5083/AA7075-PWHT.</p> Full article ">Figure 12
<p>Hardness distribution across the weld interface for all heat treatment conditions.</p> Full article ">Figure 13
<p>Showing tensile failure of (<b>a</b>) AA5083/AA7075-STA, (<b>b</b>) AA5083/AA7075-PWHT, and (<b>c</b>) AA5083/AA7075-ST.</p> Full article ">Figure 14
<p>Tensile curves of welded samples and base metals.</p> Full article ">Figure 15
<p>Fractographs of rotary friction welded samples (<b>a</b>) AA5083/AA7075-STA, (<b>b</b>) AA5083/AA7075-ST, and (<b>c</b>) AA5083/AA7075-PWHT.</p> Full article ">

Review

Jump to: Research

35 pages, 12255 KiB  
Review
A Review on Multiplicity in Multi-Material Additive Manufacturing: Process, Capability, Scale, and Structure
by Ayush Verma, Angshuman Kapil, Damjan Klobčar and Abhay Sharma
Materials 2023, 16(15), 5246; https://doi.org/10.3390/ma16155246 - 26 Jul 2023
Cited by 10 | Viewed by 4261
Abstract
Additive manufacturing (AM) has experienced exponential growth over the past two decades and now stands on the cusp of a transformative paradigm shift into the realm of multi-functional component manufacturing, known as multi-material AM (MMAM). While progress in MMAM has been more gradual [...] Read more.
Additive manufacturing (AM) has experienced exponential growth over the past two decades and now stands on the cusp of a transformative paradigm shift into the realm of multi-functional component manufacturing, known as multi-material AM (MMAM). While progress in MMAM has been more gradual compared to single-material AM, significant strides have been made in exploring the scientific and technological possibilities of this emerging field. Researchers have conducted feasibility studies and investigated various processes for multi-material deposition, encompassing polymeric, metallic, and bio-materials. To facilitate further advancements, this review paper addresses the pressing need for a consolidated document on MMAM that can serve as a comprehensive guide to the state of the art. Previous reviews have tended to focus on specific processes or materials, overlooking the overall picture of MMAM. Thus, this pioneering review endeavors to synthesize the collective knowledge and provide a holistic understanding of the multiplicity of materials and multiscale processes employed in MMAM. The review commences with an analysis of the implications of multiplicity, delving into its advantages, applications, challenges, and issues. Subsequently, it offers a detailed examination of MMAM with respect to processes, materials, capabilities, scales, and structural aspects. Seven standard AM processes and hybrid AM processes are thoroughly scrutinized in the context of their adaptation for MMAM, accompanied by specific examples, merits, and demerits. The scope of the review encompasses material combinations in polymers, composites, metals-ceramics, metal alloys, and biomaterials. Furthermore, it explores MMAM’s capabilities in fabricating bi-metallic structures and functionally/compositionally graded materials, providing insights into various scale and structural aspects. The review culminates by outlining future research directions in MMAM and offering an overall outlook on the vast potential of multiplicity in this field. By presenting a comprehensive and integrated perspective, this paper aims to catalyze further breakthroughs in MMAM, thus propelling the next generation of multi-functional component manufacturing to new heights by capitalizing on the unprecedented possibilities of MMAM. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
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Figure 1
<p>Traditional vs. additive manufacturing [<a href="#B3-materials-16-05246" class="html-bibr">3</a>].</p> Full article ">Figure 2
<p>Multi-material metal AM as per ASTM F2792-12a standard [<a href="#B4-materials-16-05246" class="html-bibr">4</a>].</p> Full article ">Figure 3
<p>Overview of applications of MMAM: (<b>a</b>–<b>d</b>) biomedical engineering, (<b>e</b>–<b>g</b>) soft robotics, and (<b>h</b>–<b>k</b>) electronics [<a href="#B7-materials-16-05246" class="html-bibr">7</a>].</p> Full article ">Figure 4
<p>Classification of DED processes [<a href="#B48-materials-16-05246" class="html-bibr">48</a>].</p> Full article ">Figure 5
<p>Schematic diagram of the DED process using powder feedstock and laser power [<a href="#B2-materials-16-05246" class="html-bibr">2</a>].</p> Full article ">Figure 6
<p>Material extrusion (adapted from [<a href="#B54-materials-16-05246" class="html-bibr">54</a>]).</p> Full article ">Figure 7
<p>Schematic diagram of the vat photopolymerization process [<a href="#B2-materials-16-05246" class="html-bibr">2</a>].</p> Full article ">Figure 8
<p>Binder jetting process [<a href="#B58-materials-16-05246" class="html-bibr">58</a>].</p> Full article ">Figure 9
<p>Material jetting process [<a href="#B64-materials-16-05246" class="html-bibr">64</a>].</p> Full article ">Figure 10
<p>LOM process; preceramic papers of Al<sub>2</sub>O<sub>3</sub> and SiC [<a href="#B1-materials-16-05246" class="html-bibr">1</a>].</p> Full article ">Figure 11
<p>(<b>a</b>) LPBF process; (<b>b</b>) EBPBF process [<a href="#B59-materials-16-05246" class="html-bibr">59</a>]. The down arrows in the figures represent the direction of movement of the build platform, while the up arrow represents the direction of motion of the dispenser.</p> Full article ">Figure 12
<p>Classification of PBF processes [<a href="#B59-materials-16-05246" class="html-bibr">59</a>].</p> Full article ">Figure 13
<p>(<b>a</b>) Representation of metal removal processes at the post-processing level, and (<b>b</b>) comparison of BTF ratios in conventional and HAM machining methods [<a href="#B74-materials-16-05246" class="html-bibr">74</a>].</p> Full article ">Figure 14
<p>Workflow in 3D printing of MMAM parts [<a href="#B89-materials-16-05246" class="html-bibr">89</a>].</p> Full article ">Figure 15
<p>Fabrication process of multi-material strain sensors [<a href="#B90-materials-16-05246" class="html-bibr">90</a>]. The arrows in the Figure signify that the nozzle is active and depositing while the cross mark represents an inactive nozzle.</p> Full article ">Figure 16
<p>Multi-ceramic sensors [<a href="#B92-materials-16-05246" class="html-bibr">92</a>].</p> Full article ">Figure 17
<p>(<b>a–d</b>) Fabrication process of multi-ceramic sensors, (<b>e</b>) schematic representation of doped-alumina matrix consisting of alumina, titanium dioxide and niobium oxide powders in a binder solution, (<b>f</b>) porous ceramic green-body due to evaporation of binder solution at 150 °C, (<b>g</b>,<b>h</b>) the titanium dioxide and niobium oxide additive solution becoming a liquid state at higher temperatures [<a href="#B92-materials-16-05246" class="html-bibr">92</a>].</p> Full article ">Figure 18
<p>(<b>a</b>) After-LENS deposited structure; (<b>b</b>) computer numerical control (CNC)-machined sample with the base; (<b>c</b>) final machined structure from a CNC machine; (<b>d</b>) validation of improved magnetic properties [<a href="#B100-materials-16-05246" class="html-bibr">100</a>].</p> Full article ">Figure 19
<p>Plot of the hardness (in GPa) along the depth (in mm) of the substrate after LENS [<a href="#B100-materials-16-05246" class="html-bibr">100</a>].</p> Full article ">Figure 20
<p>LENS process used to fabricate an Inconel 718-GRCop-84 bimetal; demonstration of the improved thermal diffusivity of the bi-metallic structure printed [<a href="#B102-materials-16-05246" class="html-bibr">102</a>].</p> Full article ">Figure 21
<p>Laser-hot wire AM process [<a href="#B114-materials-16-05246" class="html-bibr">114</a>].</p> Full article ">Figure 22
<p>Functionally graded additive manufacturing process [<a href="#B2-materials-16-05246" class="html-bibr">2</a>].</p> Full article ">Figure 23
<p>Comparison of traditional methodologies and DED and PBF processes for alloy design [<a href="#B127-materials-16-05246" class="html-bibr">127</a>].</p> Full article ">Figure 24
<p>Multiplicity in scale in MMAM [<a href="#B127-materials-16-05246" class="html-bibr">127</a>].</p> Full article ">Figure 25
<p>Multiplicity in structure in MMAM, (<b>a</b>–<b>f</b>) addition of TiC particles during wire feed processing, (<b>g</b>–<b>n</b>) particle morphology with respect to increasing particle addition, (<b>o</b>) novel Ti6Al4V + Al<sub>2</sub>O<sub>3</sub> CGM, and (<b>p</b>,<b>q</b>) TiC reaction product in a SiC reinforced titanium coating [<a href="#B3-materials-16-05246" class="html-bibr">3</a>].</p> Full article ">Figure 26
<p>Microstructures and phases in metal-based MMAM: (<b>a</b>) nitrides in BN-reinforced Ti6Al4V, (<b>b</b>) design for MMAM, (<b>c</b>,<b>d</b>) intermetallic formation at the interface of a Ti3Ni2Si-reinforced composite, (<b>e</b>) Cu alloy on IN718, (<b>f</b>) interface of an SS316 + BN composite coating, (<b>g</b>) Ti6Al4V with an increasing amount of CoCrMo [<a href="#B74-materials-16-05246" class="html-bibr">74</a>], and (<b>h</b>) reaction layers around TiN formation in TiN-reinforced Ti6Al4V [<a href="#B3-materials-16-05246" class="html-bibr">3</a>].</p> Full article ">
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