Copper-stainless steel bimetal thin-wall part and preparation method thereof

Abstract

The invention discloses a copper-stainless steel bimetal thin-wall part and a preparation method thereof, and belongs to the technical field of metal material processing. The preparation method comprises the following steps that a copper material and a steel material are prepared into a composite blank; performing first destressing heat treatment on the composite blank to obtain a bimetal cylindrical blank; the bimetal cylindrical blank is subjected to repeated spinning, and a bimetal spinning prefabricated part is manufactured; and after second destressing heat treatment is conducted on the bimetal spinning prefabricated part, machining is conducted till the dimensional tolerance of the copper-stainless steel bimetal thin-wall part is achieved. By means of the method, the metal advantages of the copper material and the steel material can be combined, low-cost manufacturing of the high-performance composite part is achieved, and therefore a traditional metal composite scheme of welding or bolt connection is replaced.

Description

Technical Field

[0001] The present application belongs to the technical field of metal material processing, and specifically relates to a copper-stainless steel bimetallic thin-walled part and a preparation method thereof. Background Art

[0002] Copper alloy and stainless steel bimetallic composites are widely used in the manufacture of various critical components across numerous industrial sectors because they combine the high electrical and thermal conductivity of copper with the high strength and corrosion resistance of stainless steel. However, the traditional production processes for thin-walled copper-steel composite components (welding or bolting) currently present numerous challenges that need to be addressed. Specifically, the traditional process has a lengthy production process and low material utilization, resulting in high production costs. At the same time, the process requires forging copper and steel separately. Not only is the required material weight large, but the operation control is extremely difficult during the forming process, and temperature uniformity is difficult to effectively guarantee. This series of problems directly causes forged products to be prone to undesirable phenomena such as cracking, uneven structure, and poor performance consistency. In addition, the traditional process also requires a welding process, and the welding process of copper alloys and stainless steel is difficult and has a high quality risk, which further affects the overall quality of the product and production stability. Therefore, there is an urgent need for a process technology that can combine the advantages of the two metals to achieve low-cost manufacturing of high-performance composite components. Summary of the Invention

[0003] The purpose of this application is to provide a copper-stainless steel bimetallic thin-walled part and a preparation method thereof, wherein the thin-walled part combines the high electrical conductivity and high thermal conductivity of copper with the high strength and corrosion resistance of stainless steel, thereby realizing the low-cost manufacturing of high-performance composite components.

[0004] To achieve the above objectives, the present application provides a method for preparing a copper-stainless steel bimetallic thin-walled part, comprising the following steps: preparing a copper material and a steel material into a composite blank; performing a first stress relief heat treatment on the composite blank to obtain a bimetallic cylindrical blank; Repeatedly spinning the bimetallic cylindrical blank to obtain a bimetallic spinning preform; After the bimetal spinning preform is subjected to a second stress relief heat treatment, it is machined to the dimensional tolerance of the copper-stainless steel bimetal thin-walled part.

[0005] Furthermore, the copper material includes at least one of copper-chromium alloy, copper-zirconium alloy, copper-chromium-zirconium alloy and copper-chromium-niobium alloy, and the steel material includes 304 stainless steel or 316 stainless steel.

[0006] Furthermore, the method of preparing the copper material and the steel material into a composite blank includes rolling bonding, explosion bonding and diffusion welding bonding.

[0007] Furthermore, the method further comprises preparing a transition layer by laser cladding at the interface of the composite copper material and the steel material, wherein the thickness of the transition layer is 50 μm to 100 μm and the material of the transition layer is nickel.

[0008] Furthermore, the heating temperature of the first stress relief heat treatment is 300° C. to 450° C., and the holding time is 60 min to 240 min.

[0009] Furthermore, the repeated spinning method includes: The first spinning is performed at a heating temperature of 400°C to 700°C with a deformation of 10% to 15%; Gradually increase the deformation amount and repeat spinning, performing annealing treatment every 2 to 3 spinning times until the spinning thinning rate reaches 30% to 70%.

[0010] Furthermore, the heating temperature of the second stress relief heat treatment is 300° C. to 500° C., and the holding time is 2 h to 6 h.

[0011] Furthermore, the machining methods include turning and milling.

[0012] Furthermore, the method further includes performing ultrasonic flaw detection on the composite blank to ensure that the interface bonding rate of the composite blank is ≥95%.

[0013] The present application also discloses a copper-stainless steel bimetallic thin-walled part, which is prepared using the above-mentioned preparation method and is particularly suitable for use in high-voltage switch contacts and rocket engine nozzle transition sections.

[0014] In summary, this application has the following advantages: 1. The preparation method of this application directly prepares copper and steel materials into a composite billet, eliminating the traditional steps of separate forging and subsequent welding of the two materials, significantly shortening the production process. Furthermore, the integrated preparation of the composite billet reduces material waste, eliminating the need for large amounts of material required for separate forging, significantly improving material utilization and reducing production costs.

[0015] 2. The preparation method of the present application performs a first stress relief heat treatment on the composite blank before spinning, which can reduce the impact of the initial stress of the blank on the spinning process; the second stress relief heat treatment is performed after spinning, which can effectively eliminate the residual stress generated by the different thermal expansion coefficients of the two materials during repeated spinning, reduce the risk of interface cracking, and ensure the bonding strength of the copper and stainless steel interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic flow chart of the method for preparing the copper-stainless steel bimetallic thin-walled part disclosed in the embodiment of this application. DETAILED DESCRIPTION

[0017] The principles and features of the present invention are described below in conjunction with the examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Where specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0018] Spinning technology, a process that uses rotating blanks and roller pressure to cause metal to plastically deform point by point, thereby forming axisymmetric parts such as cylindrical and conical shapes, offers new possibilities for forming thin-walled copper-steel composite parts. However, due to the significant differences in the material properties of copper alloys and stainless steel—for example, copper alloys (such as brass and bronze) have good plasticity and low hardness, while stainless steel (such as 304 and 316) has high strength and significant work hardening—and the different thermal expansion coefficients of the two materials, the use of spin forming to prepare copper-steel composite bimetallic parts is prone to residual stress, which may even lead to interface cracking.

[0019] Based on this, the present application provides a method for preparing a copper-stainless steel bimetallic thin-walled part, such as Figure 1 As shown, the following steps are included: S1. Prepare a composite blank from copper material and steel material.

[0020] In a specific embodiment, the copper material includes at least one of copper-chromium alloy (CuCr), copper-zirconium alloy (CuZr), copper-chromium-zirconium alloy (CuCrZr), and copper-chromium-niobium alloy (CuCrNb), and the steel material includes 304 stainless steel or 316 stainless steel.

[0021] Among them, copper-chromium alloy (CuCr), copper-zirconium alloy (CuZr), copper-chromium-zirconium alloy (CuCrZr), and copper-chromium-niobium alloy (CuCrNb) are all high-strength and high-conductivity copper alloys, with excellent properties in terms of strength and conductivity. These materials introduce elements such as Cr, Zr, and Nb, which have little effect on the conductivity of the matrix, and achieve high strength and high conductivity through second-phase strengthening and deformation strengthening. At the same time, they also have high softening temperatures, excellent high-temperature resistance, and processing properties, making them key materials used in high-tech fields. Among them, the density of 304 stainless steel is 7.93g / cm 3304 stainless steel is an austenitic stainless steel. Its main active ingredients include nickel (Ni) and chromium (Cr), with the chromium content typically ranging from 18wt% to 20wt% and the nickel content from 8wt% to 10.5wt%. It also contains small amounts of carbon (C), silicon (Si), manganese (Mn), phosphorus (P), and sulfur (S), as well as trace amounts of nitrogen (N), titanium (Ti), and molybdenum (Mo). 316 stainless steel is also an austenitic stainless steel. In addition to nickel and chromium, its main components also contain molybdenum (Mo). Its chemical composition is roughly 16.0wt% to 18.5wt% chromium (Cr), 10.0wt% to 14.0wt% nickel (Ni), 2.0wt% to 3.0wt% molybdenum (Mo), and other small amounts of carbon, silicon, manganese, phosphorus, and sulfur. The addition of molybdenum significantly affects the performance of 316 stainless steel, significantly improving its corrosion resistance in reducing media. The primary chemical difference between 316 stainless steel and 304 stainless steel is that 316 contains Mo. It's also generally accepted that 316 stainless steel is more corrosion-resistant, especially at high temperatures. Therefore, 316 stainless steel is preferred for this application in high-temperature environments. However, 304 stainless steel has slightly higher strength and hardness than 316 stainless steel. Therefore, 304 stainless steel is preferred for applications requiring pressure resistance and resistance to external friction.

[0022] The composite blank of the present application combines the advantages of copper and steel, achieving a combination of high electrical conductivity, high thermal conductivity, and high strength. In a specific embodiment, the methods for preparing the composite blank from the copper and steel materials include rolling lamination, explosion lamination, and diffusion welding lamination. Rolling, explosion, or diffusion welding lamination processes all achieve metallurgical bonding and high interfacial bonding strength. Furthermore, rolling, explosion, or diffusion welding lamination processes directly prepare the copper and steel composite blanks, eliminating the traditional steps of separate forging and subsequent welding of the two materials, significantly shortening the production process. Furthermore, the integrated preparation of the composite blank reduces material waste, eliminating the need for large amounts of material for separate forging, significantly improving material utilization and reducing production costs. Furthermore, since separate forging is not required, the problems associated with poor temperature uniformity and operational difficulty associated with separate forging of the two materials in traditional processes are avoided. The prepared composite blanks can more easily achieve uniform temperature control during subsequent processing, reducing the occurrence of undesirable phenomena such as cracking, structural inhomogeneity, and poor performance consistency in forged products, thereby improving product quality stability.

[0023] Preferably, a nickel transition layer with a thickness of 50-100 μm is deposited by laser cladding at the interface between the copper and steel materials (generally, the thickness of the copper and steel materials at the composite interface is 10-15 mm). This can alleviate the thermal expansion difference between the copper and steel to a certain extent, reduce interfacial stress, and thus prevent cracking. The nickel transition layer should not be too thick (>100 μm) to avoid cracking due to the thermal expansion difference of the transition layer itself; nor should it be too thin (<50 μm). Insufficient thickness will not effectively alleviate interfacial stress, which can easily lead to cracking during processing.

[0024] Preferably, the composite blank may be subjected to ultrasonic flaw detection to ensure that the interface bonding rate of the composite blank is ≥95%, thereby ensuring the quality stability of the blank.

[0025] In a specific embodiment, the copper material and the steel material in the composite billet are copper-chromium-zirconium alloy (CuCrZr) and 316 stainless steel, respectively; wherein, in the copper-chromium-zirconium alloy, the Cr element content is 0.2wt%~1.5wt%, the Zr element content is 0.03wt%~0.15wt%, and the balance is Cu.

[0026] In a specific embodiment, the parameters of laser cladding include: laser power of 1.5 kW to 3 kW, scanning speed of 5 mm / s to 10 mm / s, spot diameter of 1 mm to 2 mm, powder feeding rate of 8 g / min to 12 g / min, flow rate of shielding gas (Ar) of 10 L / min to 15 L / min, and preheating temperature of 200°C to 300°C.

[0027] As an optional embodiment of the present application, the rolling bonding method includes hot rolling bonding or asynchronous rolling bonding. The hot rolling bonding method uses high-temperature rolling above the recrystallization temperature of copper and stainless steel to achieve bonding through diffusion and plastic deformation. The asynchronous rolling bonding method uses different rolling speeds for the upper and lower rollers, generating shear deformation to promote interfacial bonding, making it suitable for the bonding of dissimilar materials.

[0028] In this scheme, pressure can be used to create a tight mechanical bond between the copper and steel interfaces. The composited blank has high dimensional accuracy, providing a regular initial blank shape for the subsequent spinning process and reducing the amount of additional pre-processing required for the blank. Furthermore, during the rolling process, the rolling temperature can be adjusted to achieve good interface contact while maintaining a good plasticity match between the copper and steel. This, combined with a subsequent nickel transition layer, further enhances interfacial bonding strength and reduces the risk of interface cracking during spinning.

[0029] As an optional embodiment of the present application, the explosive composite method includes a powder intermediate layer explosive composite method, an underwater explosive composite method, and a preheating explosive composite method.

[0030] In the above scheme, explosive composite uses the high-pressure shock wave generated by the detonation of explosives to cause severe plastic deformation at the interface between copper and steel and form a metallurgical bond. The bonding strength is significantly higher than that of ordinary mechanical composites, and can effectively resist the interface peeling force caused by differences in material properties during the spinning process. The process is highly compatible with the thickness combination of copper and steel materials, and is particularly suitable for preparing composite blanks with large differences in thickness of dissimilar metals to meet the structural design requirements of different thin-walled parts. In addition, the composite process is time-saving, which can avoid the formation of brittle phases between copper and steel due to element diffusion at high temperatures, ensure interface toughness, and facilitate the stability of subsequent spinning deformation.

[0031] As an optional embodiment of the present application, the diffusion welding composite method includes: hot pressing diffusion welding, hot isostatic pressing diffusion welding and transition layer assisted diffusion welding.

[0032] In the above scheme, diffusion welding composite can achieve interfacial atomic diffusion through high temperature and pressure under vacuum or protective atmosphere, which can effectively avoid oxidation or impurity intervention, and is suitable for scenarios with strict requirements on interface cleanliness (such as thin-walled parts that require high electrical / thermal conductivity). The deformation amount of the composite process is small, and the flatness and verticality accuracy of the blank are high. It can be directly used in the subsequent spinning process to reduce spinning defects caused by blank shape deviation (such as uneven wall thickness). In addition, the present application can also promote the diffusion bonding between copper-nickel and nickel-steel through the effect of diffusion welding by setting a nickel transition layer at the composite interface, forming a gradient interface structure, alleviating the difference in thermal expansion coefficients between copper and steel, and reducing residual stress concentration during high-temperature spinning.

[0033] In general, the three composite methods in this application can all provide qualified composite blanks for subsequent spinning and heat treatment processes. Among them, rolling composite tends to be economical and adaptable to mass production, explosive composite tends to be high bonding strength and material combination flexibility, and diffusion welding composite tends to be interface purity and dimensional accuracy. The appropriate composite method can be selected according to the specific application scenarios of thin-walled parts (such as mechanical performance requirements, production scale, and cost budget).

[0034] S2. Performing a first stress relief heat treatment on the composite blank to obtain a bimetallic cylindrical blank.

[0035] The stress relief heat treatment in the above scheme can eliminate the residual stress of the composite blank and stabilize the metallographic structure, thereby reducing the risk of uneven deformation or cracking caused by initial stress during the spinning process, and providing a good metallurgical foundation for subsequent spinning.

[0036] In a specific embodiment, the heating temperature of the first stress relief heat treatment is 300°C to 450°C, and the holding time is 60min to 240min. The heating temperature of the present application should not be too low, and the holding time should not be too short, otherwise it will lead to insufficient stress relief and easily cause cracking during the spinning process. The heating temperature of the present application should not be too high to avoid aggravating the diffusion at the copper-steel interface and forming brittle intermetallic compounds.

[0037] S3. Repeatedly spinning the bimetallic cylindrical blank to obtain a bimetallic spinning preform.

[0038] In a specific embodiment, the repeated spinning method includes: performing the first spinning at a heating temperature of 400°C to 700°C with a deformation of 10% to 15%; gradually increasing the deformation and performing repeated spinning, performing annealing treatment after every 2 to 3 spinning times, until the spinning thinning rate reaches 30% to 70%.

[0039] In the above scheme, spin coating is performed at a temperature between 400°C and 700°C, which reduces the material's resistance to deformation and prevents excessive diffusion at the steel-copper interface at high temperatures, leading to the formation of brittle phases. Temperatures below 400°C result in high material resistance to deformation and are prone to cracking. Temperatures above 700°C lead to significant diffusion at the steel-copper interface, significantly reducing the bond strength of the composite blank. The gradient deformation setting requires a small initial deformation (though not too small to avoid low processing efficiency. Furthermore, too small a deformation will increase the number of spinning cycles, resulting in cumulative stress. Larger deformations can lead to interface damage or material cracking). This prevents interface damage, allowing subsequent increases in deformation to improve processing efficiency. Interval annealing is employed during the spinning process, with annealing performed after every two to three spinning cycles. This eliminates work hardening, restores the material's plasticity, and prevents crack initiation. Finally, controlling the spinning thinning ratio to 30% to 70% ensures sufficient plastic deformation while avoiding interface cracking or performance degradation caused by excessive thinning. Specifically, if the thinning rate is less than 30%, the composite blank will not be fully densified, thereby reducing the strength of the bimetallic thin-walled part. If the thinning rate is greater than 70%, the composite blank will suffer from severe work hardening and plastic exhaustion, which will cause the bimetallic thin-walled part to crack during use.

[0040] Preferably, the annealing temperature is 400° C. and the holding time is 4 hours.

[0041] S4. After performing a second stress relief heat treatment on the bimetal spinning preform, the preform is machined to the dimensional tolerance of the copper-stainless steel bimetal thin-walled part.

[0042] The above solution first uses stress-relief heat treatment to eliminate residual stress from spinning, stabilize dimensions, and prevent deformation during subsequent processing. Machining then ensures that the final copper-stainless steel bimetallic thin-walled component meets dimensional requirements, further improving the overall product quality.

[0043] In a specific embodiment, the heating temperature of the second stress relief heat treatment is 300°C to 500°C, and the holding time is 2 hours to 6 hours. The temperature of the second stress relief heat treatment of this application must be strictly controlled to avoid incomplete stress relief due to too low a temperature or insufficient holding time, which may cause deformation during the machining process, and to avoid softening of the bimetallic material due to excessively high temperatures, thereby reducing the strength of the bimetallic thin-walled part.

[0044] In a specific embodiment, the machining methods include turning and milling.

[0045] In summary, the preparation method of the copper-stainless steel bimetallic thin-walled parts of the present application has at least the following advantages: (1) Through the preparation of the composite blank, the synergistic effect of two stress relief heat treatments, warm spinning and precision machining, the efficient and high-quality preparation of the copper-stainless steel bimetallic thin-walled parts is achieved. (2) The nickel transition layer of the present application is combined with the gradient spinning process to effectively relieve the interface stress, ensure the bonding strength ≥ 95%, avoid cracking, and ensure reliable interface bonding. (3) The present application performs dynamic recovery and annealing treatment during the spinning process, which can refine the grains and avoid work hardening, thereby ensuring the balance between the strength and plasticity of the copper-stainless steel bimetallic thin-walled parts. (4) The present application eliminates the residual stress in the reaction process by combining two stress relief heat treatments with precision machining, thereby ensuring that the dimensional tolerance of the thin-walled parts meets the use requirements. (5) The preparation method of the present application has high material utilization and simplified process, which can reduce the scrap rate and reduce production costs. The above solution solves key problems such as interface bonding, residual stress, and dimensional stability in the preparation of copper-steel bimetallic thin-walled parts. It is suitable for the needs of aerospace, electronics, chemical and other fields for high thermal / electrical conductivity, high strength and corrosion-resistant thin-walled parts.

[0046] This application also discloses a copper-stainless steel bimetallic thin-walled component, produced using the aforementioned method. This copper-stainless steel bimetallic thin-walled component is primarily used in components that require both the high electrical and thermal conductivity of copper and the high strength and corrosion resistance of steel. It is particularly suitable for use in high-voltage switch contacts (which require copper's electrical conductivity and stainless steel's support) and rocket engine nozzle transition sections (which require copper's thermal conductivity and stainless steel's support).

[0047] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0048] Example 1 This embodiment provides a method for preparing a copper-stainless steel bimetallic thin-walled part, comprising the following steps: (1) Prepare the blank. CuCr alloy (the mass fraction of Cr element in the alloy is 0.5%) and 304 stainless steel are selected as raw materials. Before rolling, a 50 μm nickel transition layer is pre-deposited on the composite interface by laser cladding. The composite blank is obtained by rolling and cladding. The thickness of the CuCr alloy layer and the 304 stainless steel in the composite blank is 10 mm (the same below).

[0049] The roll-bonding process involves plastic deformation, which breaks the metal at the contact surface, exposing fresh metal and forming atomic-level bonds under high pressure. Hot-rolling at 600°C promotes interdiffusion of elements and enhances bonding strength. After roll-bonding, diffusion annealing is performed to relieve residual stress.

[0050] The laser cladding parameters include: laser power of 3 kW, scanning speed of 5 mm / s, spot diameter of 1 mm, powder feeding rate of 12 g / min, flow rate of shielding gas (Ar) of 15 L / min, and preheating temperature of 300 °C.

[0051] (2) Perform ultrasonic testing on the prepared composite blank to ensure that the interface bonding rate of the composite blank is ≥95%.

[0052] (3) The composite blank is subjected to a first stress relief heat treatment to obtain a bimetallic cylindrical blank for spinning; wherein the heating temperature of the first stress relief heat treatment is 300°C and the heating and holding time is 240 minutes.

[0053] (4) Repeatedly spinning the bimetallic cylindrical blank for spinning to obtain a preform of a copper-stainless steel bimetallic thin-walled spinning part; Among them, the repeated spinning method includes: performing the first spinning at a heating temperature of 400°C with a deformation of 10%; gradually increasing the deformation and repeating the spinning, performing an annealing treatment once every three spinning times, until the spinning thinning rate reaches 50%.

[0054] The annealing temperature is 400°C and the holding time is 4 hours.

[0055] (5) The preform is subjected to a second stress relief heat treatment to reduce residual stress; wherein the heating temperature of the second stress relief heat treatment is 350°C and the heating and holding time is 3 hours.

[0056] (6) The preform after the second stress relief heat treatment is turned and milled until a copper-stainless steel bimetallic thin-walled part that meets the dimensional tolerance requirements of the drawing is obtained.

[0057] Example 2 This embodiment provides a method for preparing a copper-stainless steel bimetallic thin-walled part, comprising the following steps: (1) Prepare the blank. Select CuZr alloy (the mass fraction of Zr element in the alloy is 0.1%) and 316 stainless steel as raw materials. During the composite process, an 80 μm nickel transition layer is pre-set at the composite interface by laser cladding, and the composite blank is obtained by explosive composite.

[0058] Among them, the process of explosive composite includes: using the high-pressure shock wave generated by the detonation of explosives to cause the two metals to undergo plastic deformation, melting and diffusion at the interface, thereby achieving metallurgical bonding.

[0059] The laser cladding parameters include: laser power of 1.5 kW, scanning speed of 5 mm / s, spot diameter of 1 mm, powder feeding rate of 8 g / min, flow rate of shielding gas (Ar) of 10 L / min, and preheating temperature of 200 °C.

[0060] (2) Perform ultrasonic testing on the prepared composite blank to ensure that the interface bonding rate of the composite blank is ≥95%.

[0061] (3) The composite blank is subjected to a first stress relief heat treatment to obtain a bimetallic cylindrical blank for spinning; wherein the heating temperature of the first stress relief heat treatment is 400°C and the heating and holding time is 180 minutes.

[0062] (4) Repeatedly spinning the bimetallic cylindrical blank for spinning to obtain a preform of a copper-stainless steel bimetallic thin-walled spinning part; Among them, the repeated spinning method includes: performing the first spinning at a heating temperature of 500°C with a deformation of 10%; gradually increasing the deformation and repeating the spinning, performing an annealing treatment once every two spinning times, until the spinning thinning rate reaches 70%.

[0063] (5) Performing a second stress relief heat treatment on the preform to reduce the residual stress; wherein the heating temperature of the second stress relief heat treatment is 500°C and the heating and holding time is 2h.

[0064] (6) The preform after the second stress relief heat treatment is turned and milled until a copper-stainless steel bimetallic thin-walled part that meets the dimensional tolerance requirements of the drawing is obtained.

[0065] Example 3 This embodiment provides a method for preparing a copper-stainless steel bimetallic thin-walled part, comprising the following steps: (1) Prepare the billet. A CuCrZr alloy (with a Cr mass fraction of 1.5% and a Zr mass fraction of 0.15%) and 304 stainless steel are selected as the raw materials. Before rolling, a 100 μm nickel transition layer is pre-deposited at the composite interface by laser cladding. The composite billet is obtained by rolling and cladding.

[0066] The roll-bonding process involves plastic deformation, which breaks the metal at the contact surface, exposing fresh metal and forming atomic-level bonds under high pressure. Hot-rolling at 900°C promotes interdiffusion of elements and enhances bond strength. After roll-bonding, diffusion annealing is performed to relieve residual stress.

[0067] The laser cladding parameters include: laser power of 2 kW, scanning speed of 8 mm / s, spot diameter of 1 mm, powder feeding rate of 10 g / min, flow rate of shielding gas (Ar) of 12 L / min, and preheating temperature of 250 °C.

[0068] (2) Perform ultrasonic testing on the prepared composite blank to ensure that the interface bonding rate of the composite blank is ≥95%.

[0069] (3) The composite blank is subjected to a first stress relief heat treatment to obtain a bimetallic cylindrical blank for spinning; wherein the heating temperature of the first stress relief heat treatment is 450°C and the heating and holding time is 60 minutes.

[0070] (4) Repeatedly spinning the bimetallic cylindrical blank for spinning to obtain a preform of a copper-stainless steel bimetallic thin-walled spinning part; Among them, the repeated spinning method includes: performing the first spinning at a heating temperature of 700°C with a deformation of 15%; gradually increasing the deformation and repeating the spinning, performing an annealing treatment once every two spinning times, until the spinning thinning rate reaches 60%.

[0071] (5) The preform is subjected to a second stress relief heat treatment to reduce residual stress; wherein the heating temperature of the second stress relief heat treatment is 450°C and the heating and holding time is 3 hours.

[0072] (6) The preform after the second stress relief heat treatment is turned and milled until a copper-stainless steel bimetallic thin-walled part that meets the dimensional tolerance requirements of the drawing is obtained.

[0073] The copper-stainless steel bimetallic thin-walled components prepared in Examples 1-3 were tested for electrical conductivity, thermal conductivity, strength, and corrosion resistance. The electrical conductivity test method (or standard) was GB / T 32791. The thermal conductivity test method (or standard) was ASTM C177. The strength test method (or standard) was GB / T 228.1. The results are as follows: (1) The copper-stainless steel bimetallic thin-walled part of Example 1 has an electrical conductivity of 88% IACS, a thermal conductivity of 332 W / m∙K, and a strength of 450 MPa.

[0074] (2) The copper-stainless steel bimetallic thin-walled part of Example 2 has an electrical conductivity of 93% IACS, a thermal conductivity of 341 W / m∙K, and a strength of 500 MPa.

[0075] (3) The copper-stainless steel bimetallic thin-walled component of Example 3 has an electrical conductivity of 86% IACS, a thermal conductivity of 334 W / m∙K, and a strength of 450 MPa.

[0076] Although the specific embodiments of the present application have been described in detail, this should not be construed as limiting the scope of protection of the present application. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of the present application.

Claims

1. A method for preparing a copper-stainless steel bimetallic thin-walled part, characterized in that: The following steps are involved: preparing a copper material and a steel material into a composite blank; performing a first stress relief heat treatment on the composite blank to obtain a bimetallic cylindrical blank; Repeatedly spinning the bimetallic cylindrical blank to obtain a bimetallic spinning preform; After the bimetal spinning preform is subjected to a second stress relief heat treatment, it is machined to the dimensional tolerance of the copper-stainless steel bimetal thin-walled part.

2. The method for preparing a copper-stainless steel bimetallic thin-walled part according to claim 1, characterized in that: The copper material includes at least one of copper-chromium alloy, copper-zirconium alloy, copper-chromium-zirconium alloy and copper-chromium-niobium alloy, and the steel material includes 304 stainless steel or 316 stainless steel.

3. The method for preparing a copper-stainless steel bimetallic thin-walled part according to claim 1, characterized in that: The method for preparing the copper material and the steel material into a composite blank includes rolling composite, explosion composite and diffusion welding composite.

4. The method for preparing a copper-stainless steel bimetallic thin-walled part according to claim 1 or 3, characterized in that: The method also includes preparing a transition layer by laser cladding at the interface of the composite copper material and the steel material, wherein the thickness of the transition layer is 50 μm to 100 μm and the material of the transition layer is nickel.

5. The method for preparing a copper-stainless steel bimetal thin-walled part according to claim 1, characterized in that: The heating temperature of the first stress relief heat treatment is 300° C. to 450° C., and the holding time is 60 min to 240 min.

6. The method for preparing a copper-stainless steel bimetal thin-walled part according to claim 1, characterized in that: The repeated spinning method comprises: The first spinning is performed at a heating temperature of 400°C to 700°C with a deformation of 10% to 15%; Gradually increase the deformation amount and repeat spinning, performing annealing treatment every 2 to 3 spinning times until the spinning thinning rate reaches 30% to 70%.

7. The method for preparing a copper-stainless steel bimetal thin-walled part according to claim 1, characterized in that: The heating temperature of the second stress relief heat treatment is 300° C. to 500° C., and the holding time is 2 h to 6 h.

8. The method for preparing a copper-stainless steel bimetal thin-walled part according to claim 1, characterized in that: The machining methods include turning and milling.

9. The method for preparing a copper-stainless steel bimetal thin-walled part according to claim 1, characterized in that: The method further includes performing ultrasonic flaw detection on the composite blank to ensure that the interface bonding rate of the composite blank is ≥95%.

10. A copper-stainless steel bimetallic thin-walled part, characterized in that: Obtained according to the preparation method according to any one of claims 1 to 9.

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