High-strength and high-conductivity CuCrZr / 316L bimetallic structure material and preparation method thereof

Abstract

The invention discloses a high-strength and high-conductivity CuCrZr / 316L bimetallic structure material and a preparation method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structure material. The CuCrZr / 316L bimetallic structure is prepared by taking additive manufacturing CuCrZr powder and 316L powder as raw materials, and the interface of the bimetallic structure comprises three parts, namely a CuCrZr matrix, a transition layer and a 316L matrix. The preparation method of the CuCrZr / 316L bimetallic structure material comprises the following steps: firstly, forming a 316L matrix, forming a CuCrZr matrix on the 316L matrix, carrying out heat treatment at 500 DEG C for 30 minutes, and carrying out air cooling. According to the method, the SLM technological parameters of the CuCrZr / 316L interface are controlled, the remelting process of a forming layer at the interface is reduced, and the problem of interface hot cracks in the CuCrZr / 316L manufacturing process is solved; after heat treatment, a high-strength and high-conductivity CuCrZr / 316L bimetallic structure is obtained, the tensile strength reaches 520 MPa, and the ductility exceeds 8%; and the conductivity of the CuCrZr matrix reaches 42 * 10 < 6 > S / m.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material additive manufacturing, and in particular to a high-strength and high-conductivity CuCrZr / 316L bimetallic structural material and a preparation method thereof. Background Art

[0002] With the increasing requirements of industrial applications, the harsh service environment has put forward different performance requirements for different parts of the same component, and the limitations of a single material have become increasingly prominent.

[0003] Multi-material composite structures can make the same component have different functions in different parts. As a type of copper / steel composite structure, the CuCrZr / 316L bimetallic structure not only has the high strength and corrosion resistance of stainless steel, but also has the high thermal conductivity and electrical conductivity of copper alloy. It has the dual advantages of performance and cost, and is used as a key structural material in the fields of nuclear industry, electronics industry, aerospace, etc. Therefore, it is of great significance to develop the CuCrZr / 316L bimetallic structure to further improve the comprehensive performance of components. However, these traditional manufacturing methods can usually only form components with simple structures.

[0004] Traditional copper / stainless steel bimetallic structures are usually manufactured by welding, but the thermal properties of copper and stainless steel do not match. During the manufacturing process, the volume expansion of copper and stainless steel is different after heating, which usually leads to thermal stress at the copper / stainless steel interface. In addition, since copper and iron elements are completely soluble in liquid but cannot be dissolved in solid, copper easily diffuses into stainless steel during welding, resulting in a brittle layer at the copper / stainless steel interface. The combined effect of these two usually causes thermal cracks at the interface, which significantly affects the interface bonding performance of the CuCrZr / 316L bimetallic structure. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the above-mentioned prior art and provide a high-strength and high-conductivity CuCrZr / 316L bimetallic structural material and a preparation method thereof. The present invention cleverly uses the characteristics of the SLM forming process to prepare the CuCrZr / 316L bimetallic structural formed parts, overcoming the defects of the prior art of low strength and interface.

[0006] The present invention utilizes the characteristics of layer-by-layer construction of the selective laser melting process to allow the molding parameters and composition of each forming layer of the component to be finely controlled during the forming process, thereby controlling the formation process of the copper / stainless steel interface. By accurately controlling the SLM process parameters, the size of the molten pool during the CuCrZr / 316L interface forming process can be adjusted, thereby controlling the remelting process of the forming layer, thereby regulating the interface thermal stress and element diffusion behavior, and thereby reducing interface cracks and other defects.

[0007] The present invention is achieved through the following technical solutions:

[0008] A high-strength and high-conductivity CuCrZr / 316L bimetallic structural material, comprising a 316L matrix and a CuCrZr matrix;

[0009] The 316L matrix and the CuCrZr matrix are a CuCrZr / 316L bimetallic structural material with crack-free interfaces prepared by integral forming using the selective laser melting method.

[0010] A selective laser melting forming method for a high-strength and high-conductivity CuCrZr / 316L bimetallic structural material, comprising the following steps:

[0011] S1: Establish a three-dimensional model and design process parameters through software, and import the output model and data files into the selective laser melting forming equipment;

[0012] S2: Put the dry 316L powder into the powder bin of the selective laser melting forming equipment, fill with protective gas, and perform SLM printing on the forming substrate until the structure printing operation of the 316L matrix is completed;

[0013] S3: After the structure printing of the 316L matrix is completed, clean the remaining 316L powder in the powder bin, then put the dry CuCrZr powder into the powder bin to complete the replacement of the powder material; then fill with protective gas and continue to perform SLM printing on the 316L matrix until the structure printing operation of the CuCrZr matrix is completed;

[0014] S4: After completing the printing operation in step S3, take out the substrate to obtain a CuCrZr / 316L bimetallic structural SLM blank formed part with dense structure and crack-free interfaces.

[0015] The CuCrZr / 316L bimetallic structural SLM blank formed part obtained in the above step S4 is heat-treated to obtain a CuCrZr / 316L bimetallic structural material with high strength and high conductivity.

[0016] In the above step S2, during the structure printing operation of the 316L matrix, the process parameters of the selective laser melting forming equipment are set as follows: laser power 250 - 280 w; scanning speed 900 - 1100 mm / s; powder spreading thickness 0.03 mm; scanning spacing 0.1 mm; scanning strategy is relative rotation of 67° between upper and lower layers; forming substrate is 304 austenitic stainless steel substrate; substrate preheating temperature 120 - 140 °C; forming atmosphere is 99.9% Ar.

[0017] In the above step S3, during the structural printing operation of the CuCrZr substrate, when replacing the powder material, it is necessary to cool the forming substrate temperature to room temperature to prevent the CuCrZr powder from being oxidized at high temperatures.

[0018] In the above step S3, during the structural printing operation of the CuCrZr substrate, when printing the first five layers, the process parameters of the selective laser melting forming equipment are set as follows: laser power 250 - 280 w; scanning speed 900 - 1100 mm / s; powder spreading thickness 0.03 mm; scanning spacing 0.1 mm; scanning strategy is that the upper and lower layers rotate relatively by 67°; the printing substrate is the 316L substrate structure described in step S2; the forming substrate temperature is maintained at 120 - 140 °C; the forming atmosphere is 99.9% Ar.

[0019] In the above step S3, during the structural printing operation of the CuCrZr substrate, when printing the sixth layer, the process parameters of the selective laser melting forming equipment are set as follows: laser power 350 - 370 w; scanning speed 550 - 650 mm / s; powder spreading thickness 0.02 mm; scanning spacing 0.08 mm; scanning strategy is that the upper and lower layers rotate relatively by 67°; the forming substrate temperature is maintained at 120 - 140 °C, and the forming atmosphere is 99.9% Ar.

[0020] Perform a heat treatment process on the CuCrZr / 316L bimetallic structure material obtained in the above step S5: temperature 460 - 500 °C, holding time 30 - 120 min, air cooling.

[0021] The present invention has the following advantages and effects compared with the prior art:

[0022] The present invention adopts the forming characteristics of the SLM process and proposes to replace the powder raw materials during the SLM forming process to realize that different parts of the same part use different materials when forming the same part, thereby obtaining a CuCrZr / 316L bimetallic structure part with different functions in different parts.

[0023] Aiming at the generation of copper / stainless steel interface defects, the present invention innovatively proposes to adjust the SLM process parameters to control the interface morphology of the CuCrZr / 316L bimetallic structure, so that the brittle layer in the transition layer disappears, and a CuCrZr / 316L interface structure with dense tissue and no defects is obtained.

[0024] The CuCrZr / 316L bimetallic structure material formed by the present invention can manufacture parts with more complex structures and has better interface bonding performance compared with the traditional process.

[0025] The CuCrZr / 316L bimetallic structure material of the present invention can obtain a high strength - plasticity match and good electrical conductivity after simple heat treatment. Brief Description of the Drawings

[0026] Figure 1 is the metallographic photograph of the microstructure of the SLM-formed CuCrZr / 316L bimetallic structure in Example 1, where (a) is the metallographic photograph before corrosion and (b) is the metallographic photograph after corrosion.

[0027] Figure 2 is the interfacial element distribution of the SLM-formed CuCrZr / 316L bimetallic structure in Example 1. Detailed Description of the Preferred Embodiments

[0028] As Figures 1-2 shown. The present invention discloses a method for selective laser melting forming of a high-strength and high-conductivity CuCrZr / 316L bimetallic structure material. The following further describes the present invention in detail with specific embodiments.

[0029] Example 1:

[0030] S1. Weigh dry 316L stainless steel powder, and the powder is composed of the following components by mass percentage: Cr: 16.82%, Ni: 12.54%, Si: 0.48%, Mn: 0.26%, Mo: 2.33%, S: 0.006%, P: 0.005%, O: 0.051%, C: 0.022%, and the rest is Fe; the powder particle size is 15 - 53 μm, where D10 is 17.93 μm, D50 is 30.72 μm, and D90 is 49.78 μm;

[0031] S2. Use Solid works software to establish a three-dimensional model of the CuCrZr / 316L bimetallic structure part, slice the three-dimensional model using RP - Tools software, and import the sliced file into the selective laser melting equipment; the forming process parameters of 316L are set as follows: laser power 250w; scanning speed 1100mm / s; powder spreading thickness 0.03mm; scanning spacing 0.1mm; scanning strategy is to rotate 67° relative to the upper and lower layers; the forming process parameters of the first five layers of CuCrZr are set as follows: laser power 250w; scanning speed 1100mm / s; powder spreading thickness 0.03mm; scanning spacing 0.1mm; scanning strategy is to rotate 67° relative to the upper and lower layers; the forming process parameters above the sixth forming layer of CuCrZr are set as follows: laser power 370w; scanning speed 600mm / s; powder spreading thickness 0.03mm; scanning spacing 0.08mm; scanning strategy is to rotate 67° relative to the upper and lower layers;

[0032] S3. Put the 316L powder into the selective laser melting forming equipment, introduce 99.9% Ar gas into the forming chamber as the protective gas, use a 304 austenitic stainless steel substrate, preheat the substrate temperature to 120 °C, and then evenly cover the 316L powder on the substrate through the powder spreading device, and stack and form layer by layer;

[0033] S4. After the 316L matrix forming is completed, wait for the formed part to cool, open the forming chamber door, and clean the powder bin to ensure that all the 316L powder is completely cleaned;

[0034] S5. Weigh the dry CuCrZr powder. The powder consists of the following mass percentages: Cr: 1.23%, Si: 0.005%, Zr: 0.042%, Fe: 0.012%, O: 0.037%, and the rest is Cu; the powder particle size is 15 - 53 μm, where D10 is 17.69 μm, D50 is 29.05 μm, and D90 is 51.56 μm;

[0035] S6. Put the CuCrZr powder into the selective laser melting forming equipment, introduce 99.9% Ar gas into the forming chamber as the protective gas, preheat the substrate to 120 °C again, and then evenly cover the CuCrZr powder on the 316L matrix formed in the previous step through the powder spreading device, and stack and form layer by layer;

[0036] S7. After the CuCrZr matrix forming is completed, wait for the formed part to cool, open the forming chamber door and take out the substrate and the part; use wire cutting to cut the formed part from the substrate to obtain the CuCrZr / 316L bimetallic structure part;

[0037] S8. Heat-treat the CuCrZr / 316L bimetallic structure formed part; the heat treatment system is: hold at 500 °C for 30 min and cool in air; obtain the CuCrZr / 316L bimetallic structure part with high strength and high conductivity.

[0038] S9. Use the CuCrZr / 316L bimetallic structure parts formed in the same batch to conduct tensile property tests along the SLM building direction. The test results show that: the room temperature tensile strength reaches 510 - 517 MPa, and the elongation rate reaches more than 8%.

[0039] S10. Use the CuCrZr / 316L bimetallic structure parts formed in the same batch to conduct conductivity tests. The test results show that: the conductivity of the CuCrZr matrix reaches more than 42.4×106 S / m.

[0040] Example 2:

[0041] S11. Weigh the dry 316L stainless steel powder. The powder consists of the following components by mass percentage: Cr: 16.68%, Ni: 12.84%, Si: 0.41%, Mn: 0.25%, Mo: 2.35%, S: 0.005%, P: 0.005%, O: 0.074%, C: 0.018%, and the rest is Fe. The powder particle size is 15 - 53 μm, where D10 is 19.14 μm, D50 is 32.41 μm, and D90 is 52.33 μm.

[0042] S22. Use Solid works software to establish a three - dimensional model of the CuCrZr / 316L bimetallic structure. Use RP - Tools software to slice the three - dimensional model and import the sliced file into the selective laser melting equipment. The forming process parameters of 316L are set as follows: laser power 250w; scanning speed 1100mm / s; powder spreading thickness 0.03mm; scanning spacing 0.1mm; scanning strategy is that the upper and lower layers rotate relative to each other by 67°. The forming process parameters of the first five layers of CuCrZr are set as follows: laser power 250w; scanning speed 1100mm / s; powder spreading thickness 0.03mm; scanning spacing 0.1mm; scanning strategy is that the upper and lower layers rotate relative to each other by 67°. The forming process parameters above the sixth forming layer of CuCrZr are set as follows: laser power 370w; scanning speed 600mm / s; powder spreading thickness 0.03mm; scanning spacing 0.08mm; scanning strategy is that the upper and lower layers rotate relative to each other by 67°.

[0043] S33. Put the 316L powder into the selective laser melting forming equipment. Pass 99.9% Ar gas into the forming chamber as the protective gas. Use a 304 austenitic stainless steel substrate, preheat the substrate temperature to 120°C, and then evenly cover the 316L powder on the substrate through the powder spreading device and stack layers for forming.

[0044] S44. After the 316L matrix forming is completed, wait for the formed part to cool, open the forming chamber door, and clean the powder bin to ensure that the 316L powder is completely cleaned.

[0045] A55. Weigh the dry CuCrZr powder. The powder consists of the following components by mass percentage: Cr: 1.13%, Si: 0.008%, Zr: 0.041%, Fe: 0.04%, O: 0.067%, and the rest is Cu. The powder particle size is 15 - 53 μm, where D10 is 15.20 μm, D50 is 28.20 μm, and D90 is 51.10 μm.

[0046] S66. Put the CuCrZr powder into the selective laser melting forming equipment, introduce 99.9% Ar gas into the forming chamber as the protective gas, preheat the substrate to 120 °C again, and then evenly cover the CuCrZr powder on the 316L matrix formed in the previous step through the powder spreading device, and stack and form layer by layer;

[0047] S77. After the forming of the CuCrZr matrix is completed, wait for the formed part to cool, open the forming chamber door to take out the substrate and the part; use wire cutting to cut the formed part from the substrate to obtain a CuCrZr / 316L bimetallic structure part;

[0048] S88. Heat-treat the CuCrZr / 316L bimetallic structure formed part; the heat treatment system is: hold at 500 °C for 30 min and cool in air; obtain a CuCrZr / 316L bimetallic structure part with high strength and high conductivity.

[0049] S99. Conduct tensile property tests on the CuCrZr / 316L bimetallic structure parts formed in the same batch. The test results show that: the tensile strength at room temperature reaches 515 - 531 MPa, and the elongation rate reaches more than 8%.

[0050] S100. Conduct conductivity tests on the CuCrZr / 316L bimetallic structure parts formed in the same batch. The test results show that: the conductivity of the CuCrZr matrix reaches more than 42.1×106 S / m.

[0051] The model of the selective laser melting equipment of the present invention is EOS M280; it is a laser metal powder sintering equipment launched by EOS Gmbh of Germany in 2011, with a forming space of 250x250x325 mm; and a scanning speed of 6 m / s.

[0052] The implementation manners of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement manners and are all included in the protection scope of the present invention.

Claims

1. A high-strength and high-conductivity CuCrZr / 316L bimetallic structural material, characterized in that It includes a 316L matrix and a CuCrZr matrix; The 316L matrix and the CuCrZr matrix are a CuCrZr / 316L bimetallic structural material with crack-free interfaces prepared by selective laser melting in one piece.

2. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 1, characterized in that It includes the following steps: S1: Establish a three-dimensional model and design process parameters through software, and import the output model and data files into a selective laser melting forming device; S2: Put the dry 316L powder into the powder bin of the selective laser melting forming device, fill it with protective gas, and perform SLM printing on the forming substrate until the structural printing operation of the 316L matrix is completed; S3: After the structural printing of the 316L matrix is completed, clean the remaining 316L powder in the powder bin, then put the dry CuCrZr powder into the powder bin to complete the replacement of the powder material; then fill it with protective gas and continue to perform SLM printing on the 316L matrix until the structural printing operation of the CuCrZr matrix is completed; S4: After completing the printing operation in step S3, take out the substrate to obtain a CuCrZr / 316L bimetallic structural SLM blank formed part with dense structure and crack-free interfaces.

3. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 2, characterized in that, Heat-treat the CuCrZr / 316L bimetallic structural SLM blank formed part obtained in step S4 to obtain a CuCrZr / 316L bimetallic structural material with high strength and high conductivity.

4. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 2, characterized in that: In step S2, during the structural printing operation of the 316L matrix, the process parameters of the selective laser melting forming device are set as follows: Laser power: 250 - 280 w; Scanning speed: 900 - 1100 mm / s; Powder spreading thickness: 0.03 mm; Scanning spacing: 0.1 mm; Scanning strategy: Rotate 67° relative to each other between upper and lower layers; Forming substrate: 304 austenitic stainless steel substrate; Substrate preheating temperature: 120 - 140 °C; Forming atmosphere: 99.9% Ar.

5. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 2, characterized in that: In step S3, during the structural printing operation of the CuCrZr matrix, during the process of completing the replacement of the powder material, it is necessary to cool the temperature of the forming substrate to room temperature to prevent the CuCrZr powder from being oxidized at high temperatures.

6. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 2, characterized in that, In step S3, during the structural printing operation of the CuCrZr matrix, when printing the first five layers, the process parameters of the selective laser melting forming device are set as follows: Laser power: 250 - 280 w; Scanning speed: 900 - 1100 mm / s; Powder spreading thickness: 0.03 mm; Scanning spacing: 0.1 mm; Scanning strategy: Rotate 67° relative to each other between upper and lower layers; Printing base: The 316L matrix structure described in step S2; Forming substrate temperature: Keep at 120 - 140 °C; Forming atmosphere: 99.9% Ar.

7. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 2, characterized in that, In step S3, during the structural printing operation of the CuCrZr matrix, when printing the sixth layer, the process parameters of the selective laser melting forming device are set as follows: Laser power: 350 - 370 w; Scanning speed: 550 - 650 mm / s; Powder spreading thickness: 0.02 mm; Scanning spacing: 0.08 mm; Scanning strategy: Rotate 67° relative to each other between upper and lower layers; Forming substrate temperature: Keep at 120 - 140 °C, Forming atmosphere: 99.9% Ar.

8. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 2, characterized in that, Perform a heat treatment process on the CuCrZr / 316L bimetallic structure material obtained in step S5: temperature 460 - 500 °C, heat preservation for 30 - 120 min, and air cooling.

9. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 2, characterized in that, The 316L powder described in step S2 consists of the following mass percentage components as follows: Cr：16.68％～16.82％； Ni: 12.54% - 12.84%; Si: 0.41% - 0.48%; Mn: 0.25% - 0.26%; Mo: 2.33% - 2.35%; S：0.005％～0.006％； P：0.004％～0.005％； O：0.051％～0.074％； C：0.018％～0.022％； The balance is Fe.

10. The selective laser melting forming method of the high-strength and high-conductivity CuCrZr / 316L bimetallic structural material according to claim 2, characterized in that, The CuCrZr powder described in step S3 consists of the following mass percentage as follows: Cr：1.13％～1.23％； Si: 0.005% - 0.008%; Zr：0.041％～0.042％； Fe: 0.012% - 0.04%; O：0.037％～0.067％； The balance is Cu.

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