Hot isostatic pressure diffusion welding method for Fe-Mn-Al-C series light steel plate

Abstract

The invention discloses a hot isostatic pressure diffusion welding method for a Fe-Mn-Al-C series light steel plate. The hot isostatic pressure diffusion welding method for the Fe-Mn-Al-C series light steel plate comprises the following steps that 1, the Fe-Mn-Al-C series light steel plate is subjected to sheath welding and degassing; and 2, the product obtained in the step 1 is subjected to hot isostatic pressure diffusion welding, specifically, argon is added into hot isostatic pressure equipment to serve as a pressure medium, the pressure is increased to 100-200 MPa, meanwhile, the temperature is increased to 700-1200 DEG C, and heat preservation and pressure maintaining are conducted for 2-8 h. In the degassing stage, water vapor and oxygen in the sheath can be fully removed, a high-temperature and high-pressure hot isostatic pressure diffusion welding process is adopted, the defects of air holes, inclusions and the like in a welding seam are avoided, good welding seam quality is obtained, the strength of a welding joint is excellent, the welding efficiency is higher, and batch machining is easy to achieve.

Description

Technical Field

[0001] The invention relates to the technical field of welding the same metals, and in particular to a hot isostatic pressing diffusion welding method for a Fe-Mn-Al-C series lightweight steel plate. Background Art

[0002] In recent years, the rapid development of the automobile industry has made energy and environmental issues increasingly prominent, and achieving lightweight automobiles has become an inevitable trend in the future development of the automobile industry. Compared with traditional automobile steel, adding 5% to 6% Al by mass can reduce the weight of the vehicle body by 8% to 10%. Due to the addition of Al, Fe-Mn-Al-C lightweight steel can reduce the density and achieve lightweight automobiles while showing good mechanical properties.

[0003] The quality of welding performance is an important indicator to measure whether it can be successfully applied to automobile production. At present, the main welding methods for Fe-Mn-Al-C lightweight steel include tungsten inert gas shielded welding, metal arc welding, laser welding, electron beam welding, resistance spot welding, etc. When welding by the above welding methods, it is easy to produce defects such as segregation of alloy elements, burning of Mn elements, generation of brittle second phases, and formation of welding cracks in the weld joint, which affects the quality of the weld and the strength of the weld joint.

[0004] Hot isostatic pressing diffusion welding is a process under high temperature and high pressure that causes atomic solid phase diffusion at the interface to be connected, achieving atomic bonding. Compared with traditional welding technology, hot isostatic pressing diffusion welding technology can achieve the connection between different materials. Since no liquid phase is produced at the interface, the interface bonding strength is equivalent to that of the parent material, which can achieve good metallurgical bonding, can weld parts with complex shapes, achieve strict dimensional control and weld between brittle metals.

[0005] Chinese patent CN 116689929 A, published on September 5, 2023, discloses a hot isostatic pressing diffusion bonding method for copper and stainless steel and a copper and stainless steel welding plate. The hot isostatic pressing diffusion welding process is to increase the pressure to 100-150MPa, and at the same time increase the temperature to the hot pressing temperature of 580-650℃, keep the temperature and pressure for 2-4h, and the average tensile strength of the obtained welded joint is 77-108MPa. This invention can realize the diffusion bonding of copper / copper alloy and steel, but the hot isostatic pressing diffusion welding temperature is low and the strength of the welded joint is low. Summary of the invention

[0006] The present invention provides a hot isostatic pressing diffusion welding method for a Fe-Mn-Al-C series lightweight steel plate. By reasonably selecting hot isostatic pressing diffusion welding process parameters, the generation of defects such as pores and inclusions in the weld is avoided, good weld quality is obtained, the weld joint strength is excellent, the welding efficiency is higher, and batch welding is facilitated.

[0007] To achieve the above object, the present invention provides a hot isostatic pressing diffusion welding method for a Fe-Mn-Al-C series lightweight steel plate, the hot isostatic pressing diffusion welding method for a Fe-Mn-Al-C series lightweight steel plate comprising the following steps:

[0008] Step 1: perform sheath welding on the Fe-Mn-Al-C series lightweight steel plate and perform vacuum degassing;

[0009] Step 2: Perform hot isostatic pressing diffusion welding on the product obtained in step 1: add argon as the pressure medium to the hot isostatic pressing equipment and increase the pressure to 100-200 MPa, and at the same time increase the temperature to 700-1200°C, and keep the temperature and pressure for 2-8 hours.

[0010] Preferably, the Fe-Mn-Al-C series lightweight steel plate is surface treated before step 1: the surface to be welded and other surfaces of the Fe-Mn-Al-C series lightweight steel plate are ground and polished, and the specific steps are: the surface to be welded and other surfaces of the Fe-Mn-Al-C series lightweight steel plate are polished and ground to make them smooth and clean, and then the surface to be welded and other surfaces are rinsed with dilute hydrochloric acid with a mass concentration of 20%, and then cleaned with an ultrasonic cleaner for 10 to 30 minutes, and finally dried in a drying oven at 50 to 70°C for 30 to 60 minutes.

[0011] Preferably, in step 1, the sheath is made of stainless steel and the sheath is welded by argon arc welding.

[0012] Preferably, in step 1, aluminum silicate high-temperature wool with a thickness of 0.2 mm is laid on the contact surface between the Fe-Mn-Al-C series lightweight steel plate and the stainless steel sheath.

[0013] Furthermore, the specific steps of the vacuum degassing in step 1 are as follows: the degassing heating process is a two-stage heating process: in the first stage, the temperature is increased to 100-200°C at a heating rate of 2-5°C / min, and then the temperature is kept warm. During the insulation process, the vacuum degree is recorded every half hour, and the insulation is stopped when the vacuum degree is 1-9e-3Pa; in the second stage, the temperature is increased to 450-550°C at a heating rate of 2-5°C / min, and then the temperature is kept warm. During the insulation process, the vacuum degree is recorded every half hour, and the insulation is stopped when the vacuum degree is 1-9e-3Pa.

[0014] Preferably, the heating process in step 2 starts from room temperature, and the heating rate from heating to 700 to 1200° C. is 3 to 10° C. / min.

[0015] Preferably, the Fe-Mn-Al-C lightweight steel plate has a thickness of 3 to 12 mm.

[0016] Preferably, the chemical composition of the Fe-Mn-Al-C series lightweight steel plate is Mn: 15% to 30%, Al: 2% to 12%, C: 0.5% to 2.0%, and the rest is Fe and unavoidable impurities.

[0017] After adopting the above-mentioned hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate, the tensile strength of the Fe-Mn-Al-C lightweight steel welded joint is ≥800MPa, the yield strength is ≥530MPa, and the elongation is ≥13MPa.

[0018] Preferably, the tensile strength of the Fe-Mn-Al-C lightweight steel welded joint is ≥900MPa, the yield strength is ≥620MPa, and the elongation is ≥15MPa.

[0019] It should be noted that the hot isostatic pressing diffusion welding method for Fe-Mn-Al-C lightweight steel plates adopted in the present invention is not limited to plate-shaped Fe-Mn-Al-C lightweight steels, and Fe-Mn-Al-C lightweight steels of other weldable shapes and sizes can also be welded using the method of the present invention.

[0020] Preferably, after step 2 is completed, the coating is removed by machining to obtain a finished product, and the specific steps are: the finished product obtained in step 2 is air-cooled to room temperature and then machined to remove the coating, and the surface of the Fe-Mn-Al-C series lightweight steel is cleaned to obtain the finished product.

[0021] The present invention has the following beneficial results:

[0022] Compared with the prior art, the present invention provides a hot isostatic diffusion welding method for Fe-Mn-Al-C lightweight steel plates. In the degassing stage, the water vapor and oxygen in the sheath can be fully removed, and the high temperature and high pressure hot isostatic diffusion welding process is adopted to avoid the generation of defects such as pores and inclusions in the weld, thereby obtaining good weld quality, excellent weld joint strength, higher welding efficiency, and easy batch processing. When the temperature is raised to 700-1200°C, the melting point of the metal is reached if the temperature is too high, and the welding effect is deteriorated if the temperature is too low. The welding effect is best within this temperature range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the assembly of Fe-Mn-Al-C series lightweight steel plate and packaging. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] A hot isostatic pressing diffusion welding method for Fe-Mn-Al-C lightweight steel plates, comprising the following specific steps:

[0027] The steel plate in this embodiment is a high carbon, medium manganese austenitic Fe-Mn-Al-C lightweight steel plate with a thickness of 5 mm and a chemical composition by mass percentage of Mn: 15%, Al: 10%, C: 1%, and the rest is Fe and unavoidable impurities.

[0028] Step 1: Polish and grind the welding surface and other surfaces of the Fe-Mn-Al-C lightweight steel plate to make it smooth and clean, then soak the welding surface and other surfaces with 20% mass concentration of dilute hydrochloric acid, then clean them with an ultrasonic cleaner for 30 minutes, and finally bake them in a drying oven at 50-70°C for 60 minutes.

[0029] Step 2: Fe-Mn-Al-C lightweight steel plate is sheathed and vacuum degassed: stainless steel sheath is used, and the sheath is welded by argon arc welding. The contact surface between Fe-Mn-Al-C lightweight steel plate and stainless steel sheath is paved with aluminum silicate high-temperature cotton with a thickness of 0.2mm. The degassing heating process is a two-stage heating process: in the first stage, the temperature is raised to 200℃ at a heating rate of 5℃ / min, and then kept warm. The vacuum degree is recorded every half hour during the insulation process until the vacuum degree reaches 8e-3pa; in the second stage, the temperature is raised to 450℃ at a heating rate of 5℃ / min, and then kept warm. The vacuum degree is recorded every half hour during the insulation process, and the insulation is stopped when the vacuum degree reaches 8e-3pa.

[0030] Step 3: Perform hot isostatic pressing diffusion welding on the product obtained in step 1: add argon as the pressure medium to the hot isostatic pressing equipment and increase the pressure to 180MPa. At the same time, increase the temperature from room temperature to 780°C at a heating rate of 3°C / min, and keep the temperature and pressure for 8 hours.

[0031] Step 4: After step 3, the Fe-Mn-Al-C series lightweight steel plate is machined to remove the sheath to obtain a finished product. The specific steps are: the finished product obtained in step 3 is air-cooled to room temperature and then machined to remove the sheath, and the surface of the Fe-Mn-Al-C series lightweight steel is cleaned to obtain the finished product.

[0032] Example 2

[0033] A hot isostatic pressing diffusion welding method for Fe-Mn-Al-C lightweight steel plates, comprising the following specific steps:

[0034] The steel plate in this embodiment is a high-carbon, high-manganese austenitic Fe-Mn-Al-C lightweight steel plate with a thickness of 8 mm and a chemical composition by mass percentage of Mn: 30%, Al: 12%, C: 1%, and the rest is Fe and unavoidable impurities.

[0035] Step 1: Polish and grind the welding surface and other surfaces of the Fe-Mn-Al-C lightweight steel plate to make it smooth and clean, then soak the welding surface and other surfaces with 20% mass concentration of dilute hydrochloric acid, then clean them with an ultrasonic cleaner for 20 minutes, and finally bake them in a drying oven at 50-70°C for 50 minutes.

[0036] Step 2: Fe-Mn-Al-C lightweight steel plate is sheathed and vacuum degassed: stainless steel sheath is used, and the sheath is welded by argon arc welding. The contact surface between Fe-Mn-Al-C lightweight steel plate and stainless steel sheath is paved with aluminum silicate high-temperature cotton with a thickness of 0.2mm. The degassing heating process is a two-stage heating process: in the first stage, the temperature is raised to 200℃ at a heating rate of 3℃ / min, and then kept warm. The vacuum degree is recorded every half hour during the insulation process until the vacuum degree reaches 5e-3pa; in the second stage, the temperature is raised to 500℃ at a heating rate of 3℃ / min, and then kept warm. The vacuum degree is recorded every half hour during the insulation process, and the insulation is stopped when the vacuum degree reaches 5e-3pa.

[0037] Step 3: Perform hot isostatic pressing diffusion welding on the product obtained in step 1: Add argon as the pressure medium to the hot isostatic pressing equipment and increase the pressure to 160MPa. At the same time, increase the temperature from room temperature to 900°C at a heating rate of 5°C / min and keep the temperature and pressure for 6 hours.

[0038] Step 4: After step 3, the Fe-Mn-Al-C series lightweight steel plate is machined to remove the sheath to obtain a finished product. The specific steps are: the finished product obtained in step 3 is air-cooled to room temperature and then machined to remove the sheath, and the surface of the Fe-Mn-Al-C series lightweight steel is cleaned to obtain the finished product.

[0039] Example 3

[0040] A hot isostatic pressing diffusion welding method for Fe-Mn-Al-C lightweight steel plates, comprising the following specific steps:

[0041] The steel plate in this embodiment is a high carbon, medium manganese austenitic Fe-Mn-Al-C lightweight steel plate with a thickness of 3 mm and a chemical composition by mass percentage of Mn: 20%, Al: 12%, C: 0.8%, and the rest is Fe and unavoidable impurities.

[0042] Step 1: Polish and grind the welding surface and other surfaces of the Fe-Mn-Al-C lightweight steel plate to make it smooth and clean, then soak the welding surface and other surfaces with 20% mass concentration of dilute hydrochloric acid, then clean them with an ultrasonic cleaner for 20 minutes, and finally bake them in a drying oven at 50-70°C for 40 minutes.

[0043] Step 2: Fe-Mn-Al-C lightweight steel plate is sheathed and vacuum degassed: stainless steel sheath is used, and the sheath is welded by argon arc welding. The contact surface between Fe-Mn-Al-C lightweight steel plate and stainless steel sheath is paved with aluminum silicate high-temperature cotton with a thickness of 0.2mm. The degassing heating process is a two-stage heating process: in the first stage, the temperature is raised to 100℃ at a heating rate of 4℃ / min, and then kept warm. The vacuum degree is recorded every half hour during the insulation process until the vacuum degree reaches 3e-3pa; in the second stage, the temperature is raised to 450℃ at a heating rate of 4℃ / min, and then kept warm. The vacuum degree is recorded every half hour during the insulation process, and the insulation is stopped when the vacuum degree reaches 3e-3pa.

[0044] Step 3: Perform hot isostatic pressing diffusion welding on the product obtained in step 1: Add argon as the pressure medium to the hot isostatic pressing equipment and increase the pressure to 140MPa. At the same time, increase the temperature from room temperature to 1050°C at a heating rate of 7°C / min and keep the temperature and pressure for 4 hours.

[0045] Step 4: After step 3, the Fe-Mn-Al-C series lightweight steel plate is machined to remove the sheath to obtain a finished product. The specific steps are: the finished product obtained in step 3 is air-cooled to room temperature and then machined to remove the sheath, and the surface of the Fe-Mn-Al-C series lightweight steel is cleaned to obtain the finished product.

[0046] Example 4

[0047] The steel plate in this embodiment is a high-carbon, high-manganese austenitic Fe-Mn-Al-C lightweight steel plate with a thickness of 10 mm and a chemical composition by mass percentage of Mn: 26%, Al: 12%, C: 1.2%, and the rest is Fe and unavoidable impurities.

[0048] A hot isostatic pressing diffusion welding method for Fe-Mn-Al-C lightweight steel plates, comprising the following specific steps:

[0049] Step 1: Polish and grind the welding surface and other surfaces of the Fe-Mn-Al-C lightweight steel plate to make it smooth and clean, then soak the welding surface and other surfaces with 20% mass concentration of dilute hydrochloric acid, then clean them with an ultrasonic cleaner for 30 minutes, and finally bake them in a drying oven at 50-70°C for 60 minutes.

[0050] Step 2: Fe-Mn-Al-C lightweight steel plate is sheathed and vacuum degassed: stainless steel sheath is used, and the sheath is welded by argon arc welding. The contact surface between Fe-Mn-Al-C lightweight steel plate and stainless steel sheath is paved with aluminum silicate high-temperature cotton with a thickness of 0.2mm. The degassing heating process is a two-stage heating process: in the first stage, the temperature is raised to 180℃ at a heating rate of 5℃ / min, and then kept warm. The vacuum degree is recorded every half hour during the insulation process until the vacuum degree reaches 1e-3pa; in the second stage, the temperature is raised to 550℃ at a heating rate of 5℃ / min, and then kept warm. The vacuum degree is recorded every half hour during the insulation process, and the insulation is stopped when the vacuum degree reaches 1e-3pa.

[0051] Step 3: Perform hot isostatic pressing diffusion welding on the product obtained in step 1: add argon as the pressure medium to the hot isostatic pressing equipment and increase the pressure to 120MPa, and at the same time increase the temperature from room temperature to 1200°C, with a heating rate of 10°C / min, and keep the temperature and pressure for 2 hours. Step 4: After step 3, the Fe-Mn-Al-C series lightweight steel plate is machined to remove the sheath to obtain the finished product. The specific steps are: air cool the finished product obtained in step 3 to room temperature and then machine it to remove the sheath, and clean the surface of the Fe-Mn-Al-C series lightweight steel to obtain the finished product.

[0052] Comparative Example 1

[0053] The same as Example 4, except that the temperature in step 3 is raised from room temperature to 650°C.

[0054] Comparative Example 2

[0055] The same as Example 4, except that the temperature in step 3 is increased from room temperature to 500°C.

[0056] Table 1 Mechanical properties of Fe-Mn-Al-C lightweight steel welded joints under room temperature tensile test

[0057]

[0058]

[0059] The reason why the tensile strength, yield strength and elongation in Comparative Examples 1 and 2 are low is that the melting point of steel is high, and the hot isostatic pressing diffusion welding temperature of Comparative Examples 1 and 2 is low. When the temperature is low, the impact on the steel surface is small, and it is difficult for atoms to diffuse and weld together, so the welding effect is poor.

[0060] The description of the above embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A hot isostatic pressing diffusion welding method for Fe-Mn-Al-C lightweight steel plates, characterized in that: The hot isostatic pressing diffusion welding method of the Fe-Mn-Al-C lightweight steel plate comprises the following steps: Step 1: perform sheath welding on the Fe-Mn-Al-C series lightweight steel plate and perform vacuum degassing; Step 2: Perform hot isostatic pressing diffusion welding on the product obtained in step 1: add argon as the pressure medium to the hot isostatic pressing equipment and increase the pressure to 100-200 MPa, and at the same time increase the temperature to 700-1200°C, and keep the temperature and pressure for 2-8 hours; The Fe-Mn-Al-C lightweight steel plate used has a chemical composition percentage by mass of Mn: 15% to 30%, Al: 2% to 12%, C: 0.5% to 2.0%, and the rest is Fe and unavoidable impurities; After the hot isostatic pressing diffusion welding method of the Fe-Mn-Al-C series lightweight steel plate, the tensile strength of the Fe-Mn-Al-C series lightweight steel welded joint is ≥800MPa, the yield strength is ≥530MPa, and the elongation is ≥13MPa.

2. The hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate according to claim 1, characterized in that: Before step 1, the surface is treated: the surface to be welded and other surfaces of the Fe-Mn-Al-C series lightweight steel plate are ground and polished.

3. The hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate according to claim 1, characterized in that: The Fe-Mn-Al-C lightweight steel plate used in step 1 has a thickness of 3 to 12 mm.

4. The hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate according to claim 1, characterized in that: In the step 1, aluminum silicate high temperature cotton is laid on the contact surface between the Fe-Mn-Al-C series lightweight steel plate and the sheath.

5. The hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate according to claim 1, characterized in that: The specific steps of the vacuum degassing in step 1 are as follows: the heating process of degassing is as follows: in the first stage, the temperature is increased to 100-200°C at a heating rate of 2-5°C / min, and then the temperature is kept warm. During the insulation process, the vacuum degree is recorded every half hour, and the insulation is stopped when the vacuum degree is 1-9e-3Pa; in the second stage, the temperature is increased to 450-550°C at a heating rate of 2-5°C / min, and then the temperature is kept warm. During the insulation process, the vacuum degree is recorded every half hour, and the insulation is stopped when the vacuum degree is 1-9e-3Pa.

6. The hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate according to claim 1, characterized in that: The heating rate of step 2 to heat up to 700-1200° C. is 3-10° C. / min.

7. The hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate according to claim 2, characterized in that: The Fe-Mn-Al-C lightweight steel plate is polished and ground on the surface to be welded and other surfaces, then washed with 20% dilute hydrochloric acid, then washed with an ultrasonic cleaner for 10 to 30 minutes, and finally dried in a drying oven for 30 to 60 minutes.

8. The hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate according to claim 1, characterized in that: After step 2, the casing is removed by machining to obtain the finished product.

9. The hot isostatic pressing diffusion welding method of Fe-Mn-Al-C lightweight steel plate according to claim 8, characterized in that: The finished product obtained after step 2 is air-cooled to room temperature and then machined to remove the sheath, and the surface of the Fe-Mn-Al-C series lightweight steel is cleaned to obtain the finished product.

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