JP6819952B2 - Laminated molding metal powder and laminated molding using metal powder - Google Patents

Description

The present invention relates to a metal powder for laminated molding that realizes high formability and high strength, and a technique for manufacturing a laminated model manufactured by using the metal powder.

In recent years, additive manufacturing, commonly known as 3D printers, has rapidly attracted attention as a new manufacturing technology. The essence of this is that it is possible to create a modeled object directly from digital data such as CAD, not the 3D printer itself, and as the digitization of manufacturing spreads, the development and trial production period is shortened by operating the 3D printer. It is expected to be done. 3D printers can be broadly divided into those that use resin as a material and those that use metal powder as a material, and both 3D printers are based on additional processing.

Additive processing is a processing method that imparts a shape by adding materials and joining them to each other. Since no removal processing or deformation processing is used, it is possible to form a complicated shape in a short time (non-patented). Reference 1). Therefore, it can be used as a mold or machine part that requires precision, or as an artificial bone or tooth prosthesis that is made to order in principle. However, compared to resin-based 3D printers, metal 3D printers lag behind in the development of higher performance of shaped objects, which is due to the characteristics peculiar to metals.

In a 3D printer for metal, metal powder is sintered with a laser to melt and solidify, and the metal powder is stacked to perform modeling (see Non-Patent Document 2). Therefore, the modeled product is not a powder sintered product but a cast product, and therefore the modeled product has a solidification structure equivalent to that of the cast product, and a decrease in strength due to a defect equivalent to that of the cast product is observed. In particular, since it has coarse crystal grains that are repeatedly melted and solidified and elongated in the stacking direction, it has the disadvantage of being inferior in strength to metal products processed by conventional manufacturing methods, and is applicable to products. I had limited the range.

As a method of suppressing such a solidified structure, there is an example of grain refinement using heterologous nucleation. Metal coagulation includes homogeneous nucleation, which nucleates and solidifies in the absence of impurity particles, and heterogeneous nucleation, which nucleates from impurity particles (foreign nuclei) and solidifies. Heterogeneous nucleation is homogeneous. Since the energy for nucleation is smaller than that for nucleation, a large number of nuclei are easily generated, resulting in finer tissue. By adding a metal powder that becomes a heterogeneous nucleus to the matrix metal powder used in a 3D printer for metals, it is possible to suppress the coarsening of the structure that occurs during modeling, and at the same time, improve the formability by crystallizing equiaxed crystals. Is expected (see Non-Patent Document 3). At this time, in order to sufficiently work as a heterogeneous nucleus, it is necessary that the melting point is higher than that of the metal of the parent phase and the atomic arrangement of the metal of the mother phase is well matched.

Takeo Nakagawa, "Laminated Modeling System-New Development of 3D Copy Technology-", Kogyo Chosakai, (1996). Yuichiro Koizumi, Sekai Son, Takeshi Saito, Shingo Kurosu, Akihiko Chiba: Prototype of spring of Co-Co-Mo alloy by electron beam lamination molding, powder and powder metallurgy, 61 (2014) Toshihiko Ozeki: Solidification and solidification structure control of weld metals, Journal of Welding Society, 70 (2001) Yoshimi Watanabe, Takashi Sato: Grain refinement of cast aluminum materials with heterogeneous nuclei with small inconsistencies, Light Metals, 64 (2014) Teruo Kishi: Titanium Technical Guide, Otsuru Uchida, (1993)

Examples of the main metal used for laminated metal molding include Ti-6Al-4V, maraging steel, and aluminum alloy. In the present invention, Ti-6Al-4V, which is a Ti alloy, is selected as the matrix metal from these metals, but the material system is not limited thereto. When this Ti-6Al-4V is selected as the matrix metal, a foreign substance having a higher melting point than Ti-6Al-4V and a high atomic arrangement consistency becomes a heteronuclear substance. The degree of inconsistency δ is defined as an index for evaluating the consistency of the atomic arrangement, and is represented by Equation 1.

a indicates the lattice constant of the foreign nuclear material, and a ₀ indicates the lattice constant of the base material. The smaller the value of δ, the better the atomic arrangement consistency, and if it is 10% or less, it is considered to work as an effective foreign nucleus. (See Non-Patent Document 4).

In Ti-6Al-4V, the β phase first crystallizes as a primary crystal. After that, a phase transformation occurs at the transformation point of 995 ° C., the β phase is transformed into the α phase, and finally the two phases of the α phase and the β phase coexist at room temperature (see Non-Patent Document 5). ). Therefore, the degree of inconsistency with respect to the primary crystal β phase of Ti-6Al-4V is obtained. Table 1 shows the melting points, crystal structures, lattice constants, and inconsistencies of various intermetallic compounds containing Ti calculated using Equation 1. From Table 1, the degree of inconsistency is 10% or less for any of the intermetallic compounds. Among them, ZnTi shows the lowest value of 3.96%, and can be said to be an effective heterogeneous nucleus for Ti-6Al-4V from the viewpoint of inconsistency. However, the melting points of all the intermetallic compounds were lower than those of Ti-6Al-4V, which did not satisfy the conditions for acting as an effective heterogeneous nucleus.

Therefore, we focused on TiC, TiN, and TiB, which are carbides, nitrides, and borides of Ti. Table 2 shows the melting points, crystal structures, lattice constants and inconsistencies of TiC, TiN and TiB. From Table 2, TiC, TiN and TiB have higher melting points than Ti-6Al-4V and have a NaCl structure as a crystal structure. The degree of inconsistency is lower than 10% in all of TiC, TiN and TiB. Furthermore, TiC had the smallest value of 6.72% as a whole, and had the best values in terms of high melting point and atomic arrangement consistency, which are the conditions for an effective heterogeneous nucleus.

In the present specification, a mixed powder using heteronuclear particles used for modeling characterized by high strength and high formability in a 3D printer for metal and a method for producing a modeled body using the mixed powder are provided. In the high-intensity process, grain refinement due to the appearance of a large number of solidified nuclei due to heterogeneous nucleation is used, and in the process of high formability, equiaxed crystal crystallization due to heterogeneous nucleation is used.

A mixed powder consisting of a base metal powder used for performing modeling characterized by high strength and high formability in a 3D printer for metal and foreign nuclei particles against its solidification.

Heterogeneous nuclear particles having a high melting point with respect to the base metal powder used for performing modeling characterized by high strength and high formability in a metal 3D printer, and having high atomic arrangement consistency with the base metal.

The base metal powder used for performing modeling characterized by high strength and high formability in a metal 3D printer is Ti-6Al-4V, which has a higher melting point and an atomic arrangement with respect to Ti-6Al-4V. A mixed powder containing TiC as a heterogeneous nuclear particle with high consistency.

The base metal powder used for performing modeling characterized by high strength and high formability in a metal 3D printer is Ti-6Al-4V, which has a higher melting point and an atomic arrangement with respect to Ti-6Al-4V. The heteronuclear particles with high consistency are TiC, and they are mixed powders characterized by having a difference in particle size.

The base metal powder is Ti-6Al-4V, the heteronuclear particles are TiC, and it is characterized by high strength and high formability using a mixed powder composed of Ti-6Al-4V particles and TiC particles having different particle sizes. A model in a 3D printer for metal.

The base metal powder is Ti-6Al-4V, the heteronuclear particles are TiC, and the mixed powder consisting of Ti-6Al-4V particles and TiC particles having different particle sizes is melted and solidified by a laser in a vacuum field. A modeled body in a 3D printer for metal, which is characterized by high strength and high formability by performing and stacking the same.

The base metal powder is Ti-6Al-4V, the heteronuclear particles are TiC, and the mixed powder consisting of Ti-6Al-4V particles and TiC particles having different particle sizes is melted and solidified by a laser in a vacuum field. A modeled body in a 3D printer for metals, which is characterized by high strength due to fine grain size and high formability associated with crystallization of equiaxed crystals by stacking the same.

It is a figure which shows the procedure of manufacturing the modeled body characterized by high strength and high formability in 3D printer for metal by this invention. (A) The powder supply tank is filled with a mixed powder composed of a base metal powder and foreign nuclei particles corresponding to the base metal powder, and the inside of the chamber is made into a vacuum field. (B) After lowering the modeling table by one pitch of lamination and raising the powder supply layer by one pitch of lamination, the mixed powder is spread on the modeling table by a blade. (C) By irradiating a laser, the mixed powder for one layer is preheated, melted and solidified. Since only the base metal powder melts and solidifies, the heteronuclear particles act as solidification nuclei during heteronuclearization, and equiaxed crystal crystallization and crystal grains become finer. (D) The mixed powder is laminated on the modeled object by one pitch of the lamination, and the mixed powder is preheated, melted and solidified by irradiating with a laser. By repeating this lamination, residual heat, melting, and solidification, a modeled body characterized by high strength and high formability can be obtained. It is a figure which shows the outline of the laser irradiation condition at the time of performing the modeling in this invention. It is a figure which shows the output of the laser at the time of performing the modeling in this invention. The output of the laser is determined by the continuity and magnitude of the laser. It is a figure which shows the execution procedure of the crystal grain refinement ability investigation by the 3D printer for metal using Ti-6Al-4V as the base metal powder by this invention, and TiC as the heteronuclear particle. (A) A mold with four dents is installed on the modeling table, and a mixed powder of Ti-6Al-4V and TiC in which the amount of TiC added is changed is put into the mold. (B) The chamber is evacuated and a laser is applied to each mixed powder. (C) Since only the base metal powder melts and solidifies, the foreign nuclei particles act as solidification nuclei during the formation of foreign nuclei, and the crystal grains become finer. It is a figure which shows the shape of the mold used for the crystal grain refinement ability investigation by the 3D printer for metal using Ti-6Al-4V as a base metal powder by this invention, and TiC as a heterogeneous nucleus particle. It is a figure which shows the locus of the laser used for the crystal grain refinement ability investigation by the 3D printer for metal using Ti-6Al-4V as the base metal powder by this invention, and TiC as the heteronuclear particle. (A), (b), (c) and (d) are used in the investigation of grain refinement ability by a 3D printer for metal using Ti-6Al-4V as the base metal powder and TiC as the heteronuclear particles in the present invention. It is a structure observation photograph of a modeled body using the mixed powder of 0 vol%, 0.1 vol%, 0.2 vol% and 0.3 vol% of TiC added, respectively. The average crystal grain size of the old β phase of the model made of each mixed powder in the crystal grain refinement investigation by a 3D printer for metal using Ti-6Al-4V as the base metal powder according to the present invention and TiC as the heteronuclear particles. It is a figure which shows the measurement result and the result of the Vickers hardness test. The horizontal axis shows the type of mixed powder, and the vertical axis shows the average crystal grain size and Vickers hardness of the old β phase. It is a figure which shows the execution procedure of the laminated molding by 3D printer for metal using Ti-6Al-4V as a base metal powder by this invention, and TiC as a heterogeneous nuclear particle. (A) The powder supply tank is filled with a mixed powder composed of Ti-6Al-4V and TiC for the same, and the inside of the chamber is made into a vacuum field. (B) The modeling table is lowered by one pitch of lamination, the powder supply layer is raised by one pitch of lamination, and then the mixed powder is spread on the modeling table by a blade. (C) By irradiating a laser, the mixed powder for one layer is preheated, melted and solidified. Since only Ti-6Al-4V melts and solidifies, TiC acts as a solidification nucleus during heteronuclear nucleation, resulting in equiaxed crystal crystallization and grain refinement. (D) The mixed powder is laminated on the modeled object by one pitch of the lamination, and the mixed powder is preheated, melted and solidified by irradiating with a laser. By repeating this lamination, residual heat, melting, and solidification, a modeled body characterized by high strength and high formability can be obtained. It is a figure which shows the locus of the laser used for the laminated modeling by the 3D printer for metal which used Ti-6Al-4V as the base metal powder by this invention, and TiC as the heteronuclear particle. It is a microstructure observation photograph of the laminated cross section of the laminated model by the 3D printer for metal using Ti-6Al-4V as the base metal powder by this invention and TiC as the heteronuclear particles. (A) is a model using a mixed powder in which the amount of TiC added is 0 vol%, and (b) is a mixed powder in which the amount of TiC added is 0.3 vol%. It is a structure observation photograph of the horizontal plane of a laminated model by a 3D printer for metal using Ti-6Al-4V as a base metal powder according to the present invention and TiC as heteronuclear particles. (A) is a model using a mixed powder in which the amount of TiC added is 0 vol%, and (b) is a mixed powder in which the amount of TiC added is 0.3 vol%. It is a high-magnification microstructure observation photograph of FIG. 12, (a) is a modeled body using a mixed powder in which the amount of TiC added is 0 vol%, and (b) is a mixed powder in which the amount of TiC added is 0.3 vol%.

First, the technical features of a modeled body having high strength and high formability in the 3D printer for metal disclosed in the present invention will be shown.

In the modeled body in the 3D printer for metal disclosed in the present invention, by using a mixed powder consisting of a base metal powder and heteronuclear particles for coagulation thereof, the crystal grains were fine and uniformly grown due to the crystallization of equiaxed crystals. Has an organization.

The modeled body in the metal 3D printer disclosed in the present invention is characterized by high strength and high formability. By improving the strength of the modeled body, it is possible to develop it into materials that require strength, and by improving the formability, it is possible to suppress the pores and curvature of the modeled body and apply it to materials that require accuracy. ..

It is not desirable to impair the composition of the alloy in the metal, but in the model of the present invention, the addition of foreign nuclei particles to the base material is very small, so the change in composition is very small. On the contrary, the added heterogeneous nuclei are expected not only to pin the crystal grain growth due to the unavoidable heating added at the time of the subsequent laminated molding even after solidification, and to prevent the coarsening of the crystal grains. , It can also be expected to play a role as a strengthening phase that hinders the movement of dislocations.

Next, the technical features of the modeling method for having high strength and high formability in the metal 3D printer disclosed in the present invention will be shown.

The modeling method used in the present invention is characterized in that not only the base metal powder but also a mixed powder composed of the base metal powder and foreign nuclei particles corresponding to the base metal powder is arranged on the modeling table. FIG. 1 shows an outline of the modeling method. First, a mixed powder containing heteronuclear particles having a high melting point with respect to the base metal powder and having high atomic arrangement consistency is produced by a powder mixing device. Then, as shown in FIG. 1A, the powder supply tank is filled with the mixed powder, and the inside of the chamber is evacuated. Next, the modeling table is lowered by one pitch of lamination, the powder supply layer is raised by one pitch of lamination, and then the metal powder is spread on the modeling table by a blade (see FIG. 1 (b)). Then, by irradiating the laser, the mixed powder for one layer is preheated, melted and solidified. At this time, since only the base metal powder melts and solidifies, the heteronuclear particles act as solidification nuclei during heteronuclear nucleation, and equiaxed crystal crystallization and crystal grains become finer (Fig. 1 (c). )reference). In addition, by preheating the mixed powder, the base metal powder becomes a semi-molten state. Therefore, if the base metal powder is melted and solidified after the residual heat, the cooling rate at the time of solidification of the modeled object becomes slow, and the residual stress in the modeled object can be suppressed. When the solidification of one layer is completed, the mixed powder is similarly laminated on the modeled object by one pitch of the lamination, and the mixed powder is similarly preheated, melted and solidified by irradiating with a laser. In the present invention, modeling is performed by repeating this lamination, residual heat, melting, and solidification, and by air-cooling, a modeled body characterized by high strength and high formability can be obtained (see FIG. 1D).

The laser irradiation conditions in modeling include the laser trajectory, scanning pitch, scanning speed, and laser output shown in FIG. In the present invention, as shown in FIG. 3, the output of the laser depends on the continuity [%] and the magnitude [W] of the laser. At this time, if the continuity is 100%, the laser is a continuous wave. Is shown.

The molding of only one layer by a 3D printer for metals using Ti-6Al-4V as the base metal powder and TiC as the heteronuclear particles is given as an example of the grain refinement ability investigation, and this is the material system of the present invention. It is not specific. FIG. 4 shows the modeling procedure. First, a mold with four dents is installed on the modeling table, and a mixed powder of Ti-6Al-4V and TiC in which the amount of TiC added is changed is charged into the mold (see FIG. 4A). Next, the chamber is evacuated and a laser is applied to each mixed powder. As a result, only Ti-6Al-4V in the mixed powder is melted, so that TiC acts as a heterogeneous nucleus during solidification. Then, by air-cooling the modeled body, a modeled body in which the crystal grains are refined by the formation of heterogeneous nuclei can be obtained (see FIG. 4 (b)).

A mixed powder was prepared for use in a high-strength, high-formability model. First, as starting materials, TILO P64-45, a gas atomizing powder having a particle size of 45 μm-65 μm manufactured by Osaka Titanium Technologies Co., Ltd., and TiC Powerer 2-5 μm manufactured by High Purity Chemical Laboratory Co., Ltd. were both placed in a container having a content of 500 ml. .. This was mixed for 1 hour using a Turbler mixer (T2F) powder mixing device manufactured by Simmal Enterprises Co., Ltd. Here, in the examples, the amount of TiC added to the mixed powder was changed every 0.1 vol% from 0 vol% to 0.3 vol% to prepare four kinds of mixed powders, which limits the claims of the present invention. It's not a thing.

Next, four kinds of mixed powders in which the amount of TiC added was changed were put into the four dents in the mold whose material was SUS304 as shown in FIG. Then, the mold was fixed on the modeling table, and the inside of the device was evacuated. The purpose of creating a vacuum inside the device is to prevent oxidation of the mixed powder during laser irradiation, and at the same time, it also reduces the water content and gaps in the metal powder.

Then, by irradiating each mixed powder with a laser, only the matrix metal powder was melted. At this time, the trajectory of the laser is as shown in FIG. 6, the irradiation conditions are a scanning pitch of 0.10 mm, a scanning speed of 100 mm / s, a continuity of 25%, and the size of the laser is 150 W. The size of the modeled body is a square with a length and width of 5 mm, and the thickness is not fixed. The model is cooled in a vacuum field inside the device. At this time, the holding time may be arbitrary, and in the example, the holding time is set to 30 minutes.

The surface of the modeled object irradiated with the laser was used as the observation surface, and the structure was observed. The observation surface was wet-polished with No. 400 to No. 2000 emery paper, and then buffed with an alumina suspension having a particle size of 1 μm. Then, it was corroded with an aqueous solution of nitric acid hydrofluoric acid, and the structure was observed with an optical microscope. 7 (a), (b), (c) and (d) are modeled using mixed powders in which the amount of TiC added is 0 vol%, 0.1 vol%, 0.2 vol% and 0.3 vol%, respectively. , It is a structure observation photograph of the observation surface of the model body which was cooled by air cooling. From FIG. 7, the martensite structure, which is a quenching solidification structure of Ti-6Al-4V, and the grain boundaries of the former β phase can be confirmed in any of the shaped bodies. Furthermore, it can be seen that the crystal grains of the old β phase are finer in the model to which TiC is added.

Next, the average crystal grain size of the old β phase of each model was calculated by the Mean Liner Intercept method based on the obtained microstructure observation photograph. In addition, the Vickers hardness test of each model was conducted to investigate the mechanical properties. FIG. 8 shows the measurement results of the average crystal grain size of the old β phase and the results of the Vickers hardness test in each mixed powder together. As the amount of TiC added increases, the average crystal grain size of the old β phase becomes smaller. This is caused by an increase in the amount of nuclei produced by heterologous nucleation, and the average crystal grain size was the smallest when 0.3 vol% of TiC was added. Also in the Vickers hardness test results, the hardness increases as the amount of TiC added increases, and the mechanical properties are improved by reducing the average crystal grain size of the old β phase.

Laminated modeling using a 3D printer for metals using Ti-6Al-4V as the base metal powder and TiC as heteronuclear particles is given as an example, but this does not specify the material system of the present invention. FIG. 9 shows the modeling procedure. First, as shown in FIG. 9A, the powder supply tank is filled with a mixed powder of Ti-6Al-4V and TiC, and the inside of the chamber is evacuated. Next, the modeling table is lowered by one pitch of lamination, the powder supply layer is raised by one pitch of lamination, and then the mixed powder is spread on the modeling table by a blade (see FIG. 9B). Then, by irradiating the laser, the residual heat, melting and solidification of the mixed powder for one layer are performed. At this time, since only Ti-6Al-4V melts and solidifies, TiC acts as a nucleus during solidification, and equiaxed crystal crystallization and crystal grains become finer (see FIG. 9C). In addition, by preheating the mixed powder, Ti-6Al-4V becomes a semi-molten state. Therefore, if Ti-6Al-4V is melted and solidified after the residual heat, the cooling rate at the time of solidification of the modeled body becomes slow, and the residual stress in the modeled object can be suppressed. When the solidification of one layer is completed, the mixed powder is similarly laminated on the modeled object by one pitch of the lamination, and the mixed powder is preheated, melted and solidified by irradiating with a laser. In the present invention, modeling is performed by repeating this lamination, residual heat, melting, and solidification, and by air-cooling, a modeled body characterized by high strength and high formability can be obtained (see FIG. 9D).

A mixed powder was prepared for use in a high-strength, high-formability model. First, TILO P64-45, a gas atomizing powder having a particle size of 45 μm-65 μm manufactured by Osaka Titanium Technologies Co., Ltd. and TiC Powerer 2-5 μm manufactured by High Purity Chemical Laboratory Co., Ltd. were both placed in a container having a content of 2000 ml. This was mixed for 1 hour using a powder mixing device. Here, in Example 2, the amount of TiC added to the mixed powder was 0 vol%, and 0.3 vol%, which was the most effective in Example 1, was prepared. However, this does not limit the claims of the present invention.

Next, a mixed powder of Ti-6Al-4V and TiC was filled in a powder supply tank, and the inside of the apparatus was evacuated. The purpose of creating a vacuum inside the device is to prevent oxidation of the mixed powder during laser irradiation, and at the same time, it also reduces the water content and gaps in the metal powder. Then, the modeling table was lowered by one pitch of lamination, the powder supply layer was raised by one pitch of lamination, and the mixed powder was spread on the modeling table by a blade. The stacking 1 pitch was set to 0.10 mm, and this was repeated until the stacking thickness became 1 mm.

Then, the mixed powder was subjected to residual heat and melting by irradiating the mixed powder with a laser. At this time, the trajectory of the laser is as shown in FIG. First, residual heat was generated by irradiating a circular shape with a diameter of 10 mm with a laser, and then melting was performed in a rectangular shape having a length of 5 mm and a width of 7.5 mm. Then, a cross scan was performed for each layer so that the laser irradiation directions were reversed. The irradiation conditions are as follows: scanning pitch 0.10 mm, scanning speed 1200 mm / s, continuity 40% for residual heat, laser size 70 W, scanning pitch 0.10 mm, scanning speed 50 mm, continuity 60% for melting, laser The size was 70 W, and the size of the model was a rectangle with a length of 5 mm and a width of 7.5 mm. When the solidification of one layer was completed, the mixed powder was similarly laminated on the modeled object by one pitch of the lamination, and the mixed powder was preheated, melted and solidified by irradiating with a laser. In the present invention, modeling was performed by repeating this lamination, residual heat, melting, and solidification. The model is cooled in a vacuum field inside the device. At this time, the holding time may be arbitrary, and in the example, the holding time is set to 30 minutes.

The structure was observed using the laminated cross section of the model as the observation surface. The observation surface was wet-polished with No. 400 to No. 2000 emery paper, and then buffed with an alumina suspension having a particle size of 1 μm. Then, it was corroded with an aqueous solution of nitric acid hydrofluoric acid, and the structure was observed with an optical microscope. 11 (a) and 11 (b) are photographs of the cross-sectional structure of the observation surface of the modeled body, which was modeled using a mixed powder in which the amount of TiC added was 0 vol% and 0.3 vol%, respectively, and cooled by air cooling. Is. From FIG. 11, it can be seen that there is a gap between each layer in any model. However, comparing FIGS. 11 (a) and 11 (b), it is found that the modeled body to which 0.3 vol% of TiC is added has much fewer pores than the one to which TiC is not added. Recognize.

Next, from the obtained microstructure observation photographs, the long-axis average length of the continuous layers and the curvature average radius at the lower part were obtained. Table 3 shows the long-axis average length and the average radius of curvature of the one with 0 vol% of TiC added and the one with 0.3 vol% of TiC added. From Table 3, the ones to which 0.3 vol% of TiC was added had larger values in the major axis average length and the average radius of curvature than the ones to which TiC was not added, and by adding TiC, the continuity of the layers was obtained. It can be seen that in addition to the high-quality modeling, the modeling is performed with the curvature of the layer suppressed. It is considered that this is because TiC acts as heterogeneous nuclei particles during solidification to generate heterologous nucleation, improve the formability, and grow many equiaxed crystals evenly.

The structure was observed using the horizontal plane of the model as the observation surface. The observation surface was wet-polished with No. 220 to No. 2000 emery paper, and then buffed with an alumina suspension having a particle size of 1 μm. Then, it was corroded with an aqueous solution of nitric acid hydrofluoric acid, and the structure was observed with an optical microscope. 12 (a) and 12 (b) are photographs of the structure of the observation surface of the modeled body, which was modeled using a mixed powder in which the amount of TiC added was 0 vol% and 0.3 vol%, respectively, and cooled by air cooling. is there. As in the case of the laminated cross section on the horizontal plane, when comparing FIGS. 12 (a) and 12 (b), the modeled body to which 0.3 vol% of TiC is added has more pores than the one to which TiC is not added. It can be seen that the number has decreased. In addition, the ratio of the area occupied by the pores on the observation surface is 20.6% when the amount of TiC added is 0 vol% and 7.6% when the amount of TiC added is 0.3 vol%. The number of vacancies is decreasing. This is caused by the formation of equiaxed crystals due to heterologous nucleation, improved formability, uniform solidification, and uniform growth of equiaxed crystals.

13 (a) and 13 (b) show high-magnification tissue observation photographs of FIGS. 12 (a) and 12 (b), respectively. From FIG. 13, the former β grain boundaries and the martensite structure, which are the quenching solidification structures of Ti-6Al-4V, were observed in both of the shaped bodies. The average crystal grain size of the old β phase of each model is 63.2 μm when the amount of TiC added is 0 vol%, and 46.2 μm when the amount of TiC added is 0.3 vol%. Nucleation occurred and the structure became finer.

In the above examples, Ti-6Al-4V was used as the base metal powder, and TiC was used as the heteronuclear particles. However, there is no problem in changing the heterogeneous nucleus to other highly consistent particles, and changing Ti-6Al-4V to a metal used for laminated molding such as maraging steel and aluminum alloy, the heterogeneous nucleus. The same effect can be obtained by changing the particles to an intermetallic compound having a high melting point and good atomic arrangement consistency with respect to the selected metal. What is important is that a modeled body having high strength and high formability can be produced by modeling with a 3D printer for metal using a mixed powder composed of a base metal powder and heterogeneous nuclear particles.

The present invention can be used for molds, machine parts, etc. where accuracy is required. Furthermore, if the material is changed to a biological material, it can be used as an artificial bone or a tooth prosthesis, so that it can be used in a very wide range of manufacturing forms.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques exemplified in this specification or drawings can achieve a plurality of objectives at the same time, and achieving one of the objectives itself has technical usefulness.

Claims (7)

The base metal powder is Ti-6Al-4V, and the heteronuclear particles having a high melting point with respect to the base metal powder and having high atomic arrangement consistency with the metal powder are TiC, TiN, or TiB. Crystal grains are obtained by melting and solidifying only the base metal powder by a laser in a vacuum field on a mixed powder composed of the base metal powder and foreign nuclei particles having different particle sizes, and stacking them. A laminated model in a 3D printer for metals, which is characterized by high strength due to miniaturization and high formability associated with uniform crystallization of equiaxed crystals . The laminated model according to claim 1.
The mixed powder is preheated by a laser in a vacuum field, and only the base metal powder is melted and solidified, and by stacking these, high strength due to grain refinement and high due to uniform crystallization of equiaxed crystals. A laminated model in a 3D printer for metal, which is characterized by formability. A shaped body according to claim 1 or 2, laminated shaped body the heterogeneous core particles is TiC. The base metal powder is Ti-6Al-4V, and the heteronuclear particles having a high melting point with respect to the base metal powder and having high atomic arrangement consistency with the metal powder are TiC, TiN, or TiB. Crystal grains are formed by melting and solidifying only the base metal powder with a laser in a vacuum field on a mixed powder composed of the base metal powder and foreign nuclei particles having different particle sizes, and stacking them. A laminated model in a 3D printer for metals, which is characterized by high strength due to miniaturization and high formability associated with uniform crystallization of equiaxed crystals. The laminated model according to claim 4.
The mixed powder is preheated by a laser in a vacuum field, and only the base metal powder is melted and solidified. By stacking these, high strength and equiaxed crystal formation due to grain refinement are performed. A laminated model in a 3D printer for metals, which is characterized by its properties. A laminated shaped body according to claim 4 or 5, the laminated shaped body the heterogeneous core particles is TiC. A method for producing a laminated model characterized by high strength by grain refinement and high formability associated with uniform crystallization of equiaxed crystals using a 3D printer for metal.
Preheat by irradiating a laser on a mixed powder composed of a base metal powder and a heteronuclear particle having a high melting point, high atomic arrangement consistency, and different particle sizes with respect to the base metal powder. With the process to do
In a step of irradiating the mixed powder with a laser in a vacuum field to melt only the base metal powder, the base metal powder is Ti-6Al-4V, and the heteronuclear particles are TiC and TiN. or comprises <br/> the process is TiB, production method.