WO2021223469A1

WO2021223469A1 - Test rod design method and system for evaluating influence of loosening defect on mechanical property

Info

Publication number: WO2021223469A1
Application number: PCT/CN2021/073724
Authority: WO
Inventors: 王俊; 王国祥; 康茂东; 李建中; 宁英; 梁锦辉
Original assignee: 上海交通大学; 江苏中超航宇精铸科技有限公司
Priority date: 2020-05-08
Filing date: 2021-01-26
Publication date: 2021-11-11
Also published as: CN111710377A; CN111710377B

Abstract

The present invention provides a test rod design method for evaluating the influence of a loosening defect on the mechanical property, comprising: step S1: designing the shape and the size of a casting rod according to the national standard, wherein the diameter of the casting rod is not less than the diameter of clamping positions on both ends of a test piece required by the national standard, and the length of the casting rod is not less than the total length of the test piece required by the standard; step S2: designing a specific region of the casting rod as polyhedral or spherical; step S3: transforming the casting rod into a three-dimensional CAD model, simulating and analyzing a freezing process, and predicting the position where a shrinkage defect possibly occurs, and the severity degree of the shrinkage defect. According to the present invention, an expected casting shrinkage defect can be made at the designated position of the test piece, while no shrinkage defect occurs to other positions, and the defect is reserved within a gauge length of the test piece used for the mechanical property test.

Description

Test bar design method and system for evaluating the influence of loose defects on mechanical properties

Technical field

The invention relates to the field of sample design for the mechanical properties of metal and alloy casting, and in particular to a test bar design method and system for evaluating the influence of loose defects on the mechanical properties. In particular, it relates to a sample design and preparation method for evaluating the influence of casting porosity defects on the mechanical properties of castings.

Background technique

Metal materials are an important material basis for industry. When product structure designers choose metal materials, they usually rely on the mechanical performance data of metal materials without defects. However, in the casting production process of metal materials, loose casting often occurs. defect. Due to the lack of casting defects affecting the mechanical properties, when designing casting products, people usually design the casting structure based on the relevant performance manual data of metal materials and set a certain safety factor. There are large design margins, low material utilization, and product design. Overweight and other issues. Especially when faced with castings with a small amount of loose defects that exceed the standard, because the existing risks cannot be evaluated, the only way to deal with it is to repair or even scrap, resulting in a lot of waste of manpower and resources. Because of the lack of sample design methods and preparation methods for casting porosity defect grades, it is extremely difficult to evaluate casting porosity defect grades for the mechanical properties of castings.

After retrieval, the document "The influence of process parameters on the micropore defects and mechanical properties of ADC12 aluminum alloy die castings, Casting 2017, 66(2)" reported that ADC12 die casting aluminum alloy was the research object, and the influence of die casting process parameters on ADC12 aluminum alloy die casting was studied. The influence law of microporous defects and mechanical properties of parts, the density, microstructure and mechanical properties of castings are analyzed. The results show that the mechanical properties of castings increase first and then decrease with the increase of pouring temperature and injection speed, and decrease with the increase of high-speed switching position. At the same time, the number of micro-holes in the casting increases with the increase of high-speed switching position and injection speed. Increase. The purpose of this research is to avoid microporous defects in the castings, so as to obtain products with the best mechanical properties, and did not study the relationship between the degree of microporous defects and mechanical properties.

Patent document CN102901659B discloses a method for preparing a metal alloy sample. The method adopts vacuum suction casting equipment and uses pressure difference suction casting to form. It has high cleanliness and high efficiency, and can achieve high uniformity and accuracy of composition. The size of the test bar is Φ12mm×120mm, which solves the existence of test bar preparation methods such as powder metallurgy, investment casting, extrusion molding and ingot processing. Insufficiency such as uneven composition, difficult oxygen content control, long cycle or complicated process; can meet the strict requirements of ideal alloy test bars for standard sample preparation, alloy design, performance testing and feeding rod preparation processes. This method prepares defect-free alloy samples that are close to the ideal state, and is a sample design method to eliminate the influence of casting defects such as shrinkage porosity.

Summary of the invention

Aiming at the problem of shrinkage porosity caused by metal material casting, which is random and affected by various parameters such as the type of metal material, solidification conditions, cooling rate, feeding conditions and surrounding environment, the purpose of the present invention is to provide a method for evaluation The test bar design method and system for the influence of porosity defects on mechanical properties are designed to design a sample that can produce different grades of casting shrinkage porosity. To study and evaluate the influence of loose casting defects on mechanical properties, and to provide a basis for structural designers to formulate acceptance criteria for castings.

According to the present invention, a test bar design method for evaluating the influence of porosity defects on mechanical properties is provided, which is characterized in that it includes:

Step S1: According to the national standard, design the shape and size of the casting rod. The diameter of the casting rod shall not be less than the diameter of the clamping part at both ends of the specimen required by the national standard, and the length shall not be less than the total length of the specimen required by the standard;

Step S2: Design the specific area of the cast rod into a polyhedron or a spherical shape;

Step S3: Transform the cast rod into a three-dimensional CAD model, simulate and analyze the solidification process, and predict the location of shrinkage defects and the severity of shrinkage defects;

Step S4: Adjust the position of the center of mass and the outer diameter of the polyhedron or sphere center of the cast rod, and return to step S2 to continue execution until the shrinkage defect is located at the center of the sample;

Step S5: Record the position of the center of mass and the size of the outer diameter of the sphere or polyhedron, and complete the design of the cast rod structure;

Step S6: According to the structural design of the cast rod, it is casted in accordance with traditional investment casting or other casting methods, and then the cast rod is processed according to national standards to perform the performance test and evaluation of the mechanical properties.

Preferably, the step S2:

The specific area refers to the part where the cast rod can be used as the gauge length of the test rod after being processed.

Preferably, the step S2:

The position of the center of mass and the outer diameter of the polyhedron or the center of the sphere are variable.

Preferably, the polyhedron and the spherical shape can form a local coarse heat joint, thereby creating a loose defect.

Preferably, the step S3:

Through commercial simulation software or thermal modulus calculation, the solidification process is simulated and analyzed.

According to the present invention, a test bar design system for evaluating the influence of porosity defects on mechanical properties includes:

Module S1: According to the national standard, design the shape and size of the casting rod. The diameter of the casting rod is not less than the diameter of the clamping part at both ends of the sample required by the national standard, and the length is not less than the total length of the sample required by the standard;

Module S2: Design the specific area of the cast rod into a polyhedron or a sphere;

Module S3: Transform the cast rod into a 3D CAD model, simulate and analyze the solidification process, and predict the location of shrinkage defects and the severity of shrinkage defects;

Module S4: Adjust the position and outer diameter of the center of mass of the polyhedron or the center of the sphere, and re-call the modules S2 and S3 until the shrinkage defect is located in the center of the sample;

Module S5: Record the position of the center of mass and the size of the outer diameter of the sphere or polyhedron, and complete the design of the cast rod structure;

Module S6: According to the structural design of the cast rod, it is cast in accordance with the traditional investment casting or other casting methods, and then the cast rod is processed according to the national standards to complete the mechanical performance test and evaluation.

Preferably, the module S2:

The specific area refers to the part where the cast rod can be used as the gauge length of the test rod after being processed;

Preferably, the module S3:

A computer-readable storage medium storing a computer program according to the present invention is characterized in that, when the computer program is executed by a processor, it implements any one of the above-mentioned methods for evaluating the impact of porosity defects on mechanical properties. The steps of the test bar design method.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention can produce the desired casting shrinkage porosity defect at the designated position of the sample, but there is no shrinkage porosity defect in other positions, and keep the defect within the sample gauge length used for the mechanical property test.

2. The sample with defects cast by the present invention can be used to evaluate the influence of different grades of loose defects on the mechanical properties of castings.

3. The method of the present invention is simple, is suitable for various casting alloy materials, and can be used for evaluating the relationship between casting defects and performance in the fields of machinery manufacturing, aerospace, shipbuilding, etc., and has broad application prospects.

Description of the drawings

By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes and advantages of the present invention will become more apparent:

Fig. 1 is a schematic diagram of the size of Embodiment 1 provided by the present invention.

Fig. 2 is a schematic diagram of the size of Embodiment 2 provided by the present invention.

FIG. 3 is a schematic diagram of the size of Embodiment 3 provided by the present invention.

Fig. 4 is a schematic diagram of the size of the polyhedron of Example 4 provided by the present invention.

Fig. 5 is a schematic diagram of the simulation result of Embodiment 1 provided by the present invention.

FIG. 6 is a schematic diagram of the simulation result of Embodiment 2 provided by the present invention.

FIG. 7 is a schematic diagram of the simulation result of Embodiment 3 provided by the present invention.

FIG. 8 is a schematic diagram of the simulation result of Embodiment 4 provided by the present invention.

FIG. 9 is a schematic diagram of the color scale of the simulation result of the embodiment provided by the present invention.

Figure 10 is a schematic diagram of the cast rod and sample combination provided by the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Specifically, the step S2:

Specifically, the polyhedron and the spherical shape can form a locally thick hot joint, thereby creating a loose defect.

Specifically, the step S3:

The test bar design system for evaluating the influence of porosity defects on mechanical properties provided by the present invention can be realized through the step flow of the test bar design method for evaluating the influence of porosity defects on mechanical properties provided by the present invention. Those skilled in the art can understand the test bar design method for evaluating the influence of porosity defects on mechanical properties as a preferred example of the test bar design system for evaluating the influence of porosity defects on mechanical properties.

Module S1: According to the national standard, design the shape and size of the cast rod. The diameter of the cast rod is not less than the diameter of the clamping part at both ends of the sample required by the national standard, and the length is not less than the total length of the sample required by the standard;

Specifically, the module S2:

Specifically, the module S3:

Hereinafter, the present invention will be explained more specifically through preferred examples.

Preferred example 1:

Figures 1, 2, 3, and 4 are schematic diagrams of the dimensions of the test bars in Examples 1, 2, 3, and 4, respectively. Fig. 5 is a distribution diagram of shrinkage porosity defects of the test bar in Example 1 after solidification. The uniform color scale is shown in Figure 9. The color gradient from black to white indicates an increase in the severity of shrinkage. In the same way, Figures 6, 7, and 8 are the shrinkage and porosity distribution diagrams of the test bars in Examples 2, 3, and 4 after solidification. Examples 1, 2, and 3 are high-temperature alloy K4169, initial temperature 1450°C, investment casting, mold shell is mullite, initial temperature 950°C; Example 4 is aluminum alloy ZL101A, initial temperature 700°C, sand casting, Resin sand, the initial temperature is 30℃. Figure 10 is a schematic diagram of the cast rod and the sample. Figure a) The cast rod is machined into a sample of Figure b).

Example 1: Select a radius of 10 mm as the radius of the sphere, and the defect shown in FIG. 5 is obtained.

Embodiment 2: The radius of 12.5 mm is selected as the radius of the sphere, and the defect shown in FIG. 6 is obtained.

Embodiment 3: The radius of 15mm is selected as the radius of the sphere, and the defect shown in FIG. 7 is obtained.

Example 4: Polyhedron with a circumscribed radius of 11 mm, and the defect shown in FIG. 8 is obtained.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, rather than indicating or implying the pointed device Or the element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present application.

Those skilled in the art know that, in addition to implementing the system, device and various modules provided by the present invention in a purely computer-readable program code manner, it is completely possible to make the system, device and various modules provided by the present invention by logically programming method steps The same program is implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system, device and various modules provided by the present invention can be regarded as a kind of hardware component, and the modules included in it for implementing various programs can also be regarded as the structure within the hardware component; The modules for realizing various functions can be regarded as both software programs for realizing methods and structures within hardware components.

The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

A test bar design method for evaluating the influence of loose defects on mechanical properties, which is characterized in that it includes:

Step S1: According to the national standard, design the shape and size of the casting rod. The diameter of the casting rod shall not be less than the diameter of the clamping part at both ends of the specimen required by the national standard, and the length shall not be less than the total length of the specimen required by the standard;

Step S2: Design the specific area of the cast rod into a polyhedron or a spherical shape;

Step S3: Transform the cast rod into a three-dimensional CAD model, simulate and analyze the solidification process, and predict the location of shrinkage defects and the severity of shrinkage defects;

Step S4: Adjust the centroid position and outer diameter of the polyhedron or sphere center of the cast rod, and return to step S2 to continue execution until the shrinkage defect is located at the center of the sample;

Step S5: Record the position of the center of mass and the size of the outer diameter of the sphere or polyhedron, and complete the design of the cast rod structure;

Step S6: According to the structural design of the cast rod, it is casted in accordance with traditional investment casting or other casting methods, and then the cast rod is processed according to national standards to perform the performance test and evaluation of the mechanical properties.
The test bar design method for evaluating the influence of porosity defects on mechanical properties according to claim 1, wherein the step S2:

The specific area refers to the part where the cast rod can be used as the gauge length of the test rod after being processed.
The test bar design method for evaluating the influence of porosity defects on mechanical properties according to claim 1, wherein the step S2:

The position of the center of mass and the outer diameter of the polyhedron or the center of the sphere are variable.
The test bar design method for evaluating the influence of porosity defects on mechanical properties according to claim 1, characterized in that the polyhedron and the spherical shape can form locally coarse heat joints, thereby producing porosity defects.
The test bar design method for evaluating the influence of porosity defects on mechanical properties according to claim 1, wherein the step S3:

Through commercial simulation software or thermal modulus calculation, the solidification process is simulated and analyzed.
A test bar design system for evaluating the influence of loose defects on mechanical properties, which is characterized in that it includes:

Module S1: According to the national standard, design the shape and size of the cast rod. The diameter of the cast rod is not less than the diameter of the clamping part at both ends of the sample required by the national standard, and the length is not less than the total length of the sample required by the standard;

Module S2: Design the specific area of the cast rod into a polyhedron or a sphere;

Module S3: Transform the cast rod into a 3D CAD model, simulate and analyze the solidification process, and predict the location of shrinkage defects and the severity of shrinkage defects;

Module S4: Adjust the position and outer diameter of the center of mass of the polyhedron or the center of the sphere, and re-call the modules S2 and S3 until the shrinkage defect is located in the center of the sample;

Module S5: Record the position of the center of mass and the size of the outer diameter of the sphere or polyhedron, and complete the design of the cast rod structure;

Module S6: According to the structural design of the cast rod, it is cast in accordance with traditional investment casting or other casting methods, and then the cast rod is processed according to national standards to perform mechanical performance testing and evaluation.
The test bar design system for evaluating the influence of porosity defects on mechanical properties according to claim 6, wherein the module S2:

The specific area refers to the part where the cast rod can be used as the gauge length of the test rod after being processed;

The position of the center of mass and the outer diameter of the polyhedron or the center of the sphere are variable.
The test bar design system for evaluating the influence of porosity defects on mechanical properties according to claim 6, characterized in that the polyhedron and the spherical shape can form locally coarse heat joints, thereby creating porosity defects.
The test bar design system for evaluating the influence of porosity defects on mechanical properties according to claim 6, wherein the module S3:

Through commercial simulation software or thermal modulus calculation, the solidification process is simulated and analyzed.
A computer-readable storage medium storing a computer program, characterized in that, when the computer program is executed by a processor, the test for evaluating the influence of porosity defects on mechanical properties according to any one of claims 1 to 5 is realized. The steps of the stick design method.