An in-situ heat treatment method for multi-channel lasers

Abstract

The present invention discloses a multi-laser in-situ heat treatment method, comprising the following steps: (1) preparing a Ti6Al4V alloy powder material by a gas atomization method; (2) spreading the Ti6Al4V alloy powder material into a layer and sintering it by laser; (3) scanning the sintered Ti6Al4V alloy structure by a first laser, using a laser power of 340W-360W, a layer thickness of 60#imgabs0#, a scanning speed of 900-1100mm / s, a scanning spacing of 0.10mm, and a spot diameter of 70-85#imgabs1#; (4 ) 1s after step (3) is completed, a second laser Ti6Al4V alloy sintered layer is selected for a single scan, the laser power used is 365W-385W, the scanning speed is 1200-1500mm / s, the scanning spacing is 0.10mm, and the spot diameter is 110-130#imgabs2#, completing the heat treatment of a layer of material; (5) After step (4) is completed, wait for 10s, and then spread the Ti6Al4V alloy powder material on the layer of material; (6) repeat steps (2)-(5) until a three-dimensional structure of Ti6Al4V alloy is formed.

Description

Technical Field

[0001] The invention belongs to the field of alloy forming, and in particular relates to a multi-laser in-situ heat treatment method. Background Art

[0002] Prior art generally uses SLM (Solid Light Molding) methods to obtain Ti6Al4V alloy structures. The resulting Ti6Al4V alloy structures exhibit acicular α-martensite in the horizontal microstructure, resulting in poor ductility. However, conventional methods for improving ductility include high-temperature preheating or heat treatment, which reduces the strength of the lattice structure and the efficiency of SLM manufacturing. Furthermore, conventional methods require the Ti6Al4V alloy structure to be formed before undergoing high-temperature preheating or heat treatment. Therefore, the high-temperature forming process is a two-step process: the formed structure must be removed and placed in a heat treatment device for heat treatment. This process can affect the purity of the formed Ti6Al4V alloy structure due to exposure to air, and the temperature drop during transfer affects the efficiency of the heat treatment. Prior art also utilizes 3D printing to obtain Ti6Al4V alloy structures. These typically involve laser sintering Ti6Al4V alloy powder to form a layer, which is then heat-treated once through laser scanning. A further layer of powder is then applied on top, sintered, and heat-treated again. In this way, forming and heat treatment are performed simultaneously. Although this simultaneous heat treatment is efficient and does not sacrifice strength, the ductility of the alloy cube after heat treatment is poor. Summary of the Invention

[0003] The purpose of the present invention is to improve the ductility of the formed structure of the Ti6Al4V alloy without affecting the strength of the formed structure.

[0004] To achieve the above object, the present invention provides the following technical solution: a multi-laser in-situ heat treatment method, characterized in that it includes the following steps:

[0005] (1) Preparation of Ti6Al4V alloy powder material by gas atomization method;

[0006] (2) Spreading the Ti6Al4V alloy powder material into a layer and sintering it by laser;

[0007] (3) The sintered Ti6Al4V alloy structure was scanned once by the first laser, with a laser power of 340W-360W and a layer thickness of 60 , scanning speed is 900-1100mm / s, scanning spacing is 0.10mm, spot diameter is 70-85 ;

[0008] (4) 1s after step (3) is completed, the second laser Ti6Al4V alloy sintered layer is scanned once, the laser power used is 365W-385W, the scanning speed is 1200-1500mm / s, the scanning spacing is 0.10mm, and the spot diameter is 110-130 , complete the heat treatment of a layer of material;

[0009] (5) After scanning in step (4), wait for 10 seconds, and then spread Ti6Al4V alloy powder material on the layer of material;

[0010] (6) Repeat steps (2) to (5) until a three-dimensional structure of Ti6Al4V alloy is formed.

[0011] Preferably, the average particle size of the Ti6Al4V alloy powder material prepared by gas atomization in step (1) is 40 .

[0012] Preferably, the focal length of the sintering laser in step (2) is 2 , the laser beam diameter is 88 .

[0013] Preferably, the spot diameter of the first laser in step (3) is 80 .

[0014] Preferably, the spot diameter of the second laser in step (4) is 120 .

[0015] Preferably, the method further comprises step (7): performing X-ray diffraction on the three-dimensional structure of the Ti6Al4V alloy formed in step (6).

[0016] Preferably, the Ti6Al4V alloy three-dimensional structure in step (6) is a rectangular parallelepiped structure of 90 mm*12 mm*17 mm.

[0017] The present invention has the following beneficial effects: The Ti6Al4V alloy structure formed by the method of the present invention can significantly increase the ductility of the alloy structure while maintaining the strength of the Ti6Al4V alloy structure, solving the problem that traditional SLM-formed Ti6Al4V alloy structures undergo heat treatment to improve ductility at the expense of reduced lattice strength. Furthermore, the present invention conducts heat treatment while the alloy is being formed, solving the problems of the traditional step-by-step forming and heat treatment process, where air contact affects purity, and where temperature reduction during transfer affects heat treatment efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For those skilled in the art, other relevant drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic diagram showing the laser focal plane of the present invention;

[0020] Figure 2 This is a scanning electron microscope image after the first laser irradiation of the present invention;

[0021] Figure 3 This is a scanning electron microscope image after the second laser irradiation of the present invention;

[0022] Figure 4 Schematic diagram of temperature changes over time during the scanning process of the present invention;

[0023] Figure 5 This is a comparison chart of the strength and ductility data of the Ti6Al4V alloy after receiving laser scanning and the Ti6Al4V alloy after two laser scans;

[0024] Figure 6 is the X-ray diffraction pattern of the present invention;

[0025] Figure 7 Schematic diagram of the in-situ heat treatment according to the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by the first technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by the first technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0029] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0030] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0031] Example

[0032] The following are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the following embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.

[0033] A multi-laser in-situ heat treatment method comprises the following steps:

[0034] (1) Preparation of Ti6Al4V alloy powder material by gas atomization method;

[0035] (2) Spreading the Ti6Al4V alloy powder material into a layer and sintering it by laser;

[0036] (3) The sintered Ti6Al4V alloy structure was scanned once by the first laser, with a laser power of 350W and a layer thickness of 60 , scanning speed is 1000mm / s, scanning spacing is 0.10mm, spot diameter is 80 ;

[0037] (4) 1s after step (3) is completed, the second laser Ti6Al4V alloy structure is scanned once, the laser power used is 375W, and the layer thickness is 60 , scanning speed is 1392mm / s, scanning spacing is 0.10mm, spot diameter is 120 , complete the heat treatment of a layer of material;

[0038] (5) After scanning in step (4), wait for 10 seconds, and then spread Ti6Al4V alloy powder material on the layer of material;

[0039] (6) Repeat steps (2) to (5) until a three-dimensional structure of Ti6Al4V alloy is formed.

[0040] First, Ti6Al4V alloy powder materials were prepared by gas atomization method. Most of the particle sizes of Ti6Al4V alloy powder materials were 30-50 , the average particle size is 40 , meet the particle size requirements of laser selective first metal powder. Figure 1 , is the laser focal plane for laser sintering. In step (2), the focal length of the sintering laser is 2 , the laser beam diameter is 88 . Refer to the manual attached Figure 2-3 ,from Figure 2 It can be seen that after the first laser scan of the sintered Ti6Al4V alloy structure, there is still only needle-shaped α martensite (i.e. α phase) in the Ti6Al4V alloy structure, which is the same as the traditional Ti6Al4V alloy structure and has weak ductility. Figure 3After the second laser scan, columnar β grains (i.e., β phase) appear in the Ti6Al4V alloy structure. Therefore, after the second laser scan, the Ti6Al4V alloy structure contains needle-shaped α martensite and columnar β grains (the entire alloy body is α+β phase). At this time, the leaching has strong ductility. In order to verify this conclusion, the ductility test of the Ti6Al4V alloy structure after the first laser scan and the Ti6Al4V alloy formed after two laser scans was carried out. Figure 5 From the diffraction index, we can see that the ductility of the Ti6Al4V alloy formed after two laser scans is higher than that of the Ti6Al4V alloy structure after the first laser scan. Figure 5 The strength of the Ti6Al4V alloy formed after two laser scans is almost the same as the yield strength and tensile strength of the Ti6Al4V alloy structure formed after the first laser scan. Therefore, the Ti6Al4V alloy structure formed by the method of the present invention can greatly increase the ductility of the alloy structure while ensuring the strength of the Ti6Al4V alloy structure, solving the problem that the traditional SLM-formed Ti6Al4V alloy structure undergoes heat treatment to improve ductility at the expense of reducing the strength of the lattice structure. Figure 6 The three-dimensional structure of the Ti6Al4V alloy formed by this invention can be clearly identified through X-ray diffraction analysis of the diffraction angle-intensity spectrum of the α+β phase. This also demonstrates that the structural changes in the Ti6Al4V alloy formed after two laser scans significantly increase the ductility of the alloy while maintaining its strength.

[0041] Reference Manual Figure 7 The two laser parameters for heat treatment are different. The laser spot in the rear scan should be larger than the laser spot in the front scan. At the same time, the laser power also needs to be increased to promote the transformation of acicular α martensite in the Ti6Al4V alloy structure into columnar β grains.

[0042] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A multi-laser in-situ heat treatment method, characterized in that: The steps include: (1) Preparation of Ti6Al4V alloy powder material by gas atomization method; (2) Spreading the Ti6Al4V alloy powder material into a layer and sintering it by laser; (3) The sintered Ti6Al4V alloy structure is scanned once by the first laser, and the laser power used is 340W-360W. The thickness of the layer of Ti6Al4V alloy powder material in step (2) is 60 , scanning speed is 900-1100mm / s, scanning spacing is 0.10mm, spot diameter is 70-85 ; (4) 1s after step (3) is completed, the second laser Ti6Al4V alloy sintered layer is scanned once, the laser power used is 365W-385W, the scanning speed is 1200-1500mm / s, the scanning spacing is 0.10mm, and the spot diameter is 110-130 , complete the heat treatment of a layer of material; (5) After scanning in step (4), wait for 10 seconds, and then spread Ti6Al4V alloy powder material on the layer of material; (6) Repeat steps (2) to (5) until a three-dimensional structure of Ti6Al4V alloy is formed.

2. The multi-laser in-situ heat treatment method according to claim 1, characterized in that: The average particle size of the Ti6Al4V alloy powder material prepared by gas atomization in step (1) is 40 .

3. The multi-laser in-situ heat treatment method according to claim 1, characterized in that: The focal length of the sintering laser in step (2) is 2 , the laser beam diameter is 88 .

4. The multi-laser in-situ heat treatment method according to claim 1, characterized in that: The spot diameter of the first laser in step (3) is 80 .

5. The multi-laser in-situ heat treatment method according to claim 1, characterized in that: The spot diameter of the second laser in step (4) is 120 .

6. The multi-laser in-situ heat treatment method according to claim 1, characterized in that: The method further includes step (7): performing X-ray diffraction on the three-dimensional structure of the Ti6Al4V alloy formed in step (6).

7. The multi-laser in-situ heat treatment method according to claim 1, characterized in that: The Ti6Al4V alloy three-dimensional structure in step (6) is a rectangular parallelepiped structure of 90 mm*12 mm*17 mm.

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