Method for controlling the grain corrosion performance and mechanical strength of austenitic stainless steel clad plate

Abstract

The application is suitable for austenitic stainless steel clad plate production and manufacturing, and a control method for the intergranular corrosion performance and mechanical strength of the austenitic stainless steel clad plate. Different heat treatment processes are formulated according to different raw material performances to meet the production needs of the clad plate. The chemical composition and performance of the raw material are controlled to improve and enhance the quality of the clad plate product. The problems of low elongation and decreased intergranular corrosion performance of the austenitic stainless steel clad plate in the high-temperature tempering process are solved. The problems of the clad plate in the later manufacturing process, such as difficult processing, and the problems of the austenitic stainless steel clad plate after high-temperature tempering, such as high yield ratio and low elongation, are solved. The requirements of customers for the corrosion resistance of the clad plate of some special materials are met. Since the application is implemented, the bottleneck problem of the corrosion resistance reduction of the austenitic stainless steel clad plate in the high-temperature tempering process is completely solved, the heat treatment cost of the clad plate is reduced, and the special requirements of special materials for the clad plate are met.

Description

Technical Field

[0001] This invention relates to the field of composite material manufacturing, specifically to a method for controlling the crystal corrosion performance and mechanical strength of austenitic stainless steel composite plates. Background Technology

[0002] Metal composite materials are generally produced using an open-air explosive bonding process. This involves using explosives to bond two or more metals together. Composite materials produced through this method exhibit significant strength enhancement, manifested in increased tensile strength and yield strength, and decreased elongation. The degree of this enhancement depends on the explosive welding process parameters and the properties of the substrate itself. After explosive bonding, stress relief is typically achieved through either normalizing or high-temperature tempering heat treatment.

[0003] Normalizing composite materials using an electric resistance furnace yields materials with stable mechanical properties and excellent corrosion resistance. However, the high normalizing temperature leads to high energy consumption and the formation of a large amount of oxide scale in the base material, negatively impacting quality and cost. While high-temperature tempering is energy-efficient, it also has quality-related issues. For example, it can severely reduce the intergranular corrosion resistance of some composite materials, fail to effectively eliminate explosion hardening, and result in low plasticity in composite materials subjected to high-temperature tempering.

[0004] Due to the lack of effective systematic solutions, existing high-temperature tempering methods have not been widely adopted, and they also pose quality risks and reduce product lifespan. This significantly hinders the promotion of high-temperature tempering technology and restricts the development of the composite materials industry.

[0005] The purpose of this invention is to solve the problem of high-temperature tempering corrosion resistance in austenitic stainless steel composite plates. It meets the corrosion resistance requirements of austenitic stainless steel composite plates made from certain special materials, and formulates different heat treatment regimes based on the properties of different raw materials to meet the needs of composite plate production, thereby improving the operability of high-temperature tempering for austenitic stainless steel composite plates. It also meets the requirements of energy conservation, emission reduction, and environmental protection in composite plate production. Furthermore, it solves the problem of corrosion detection in composite plates being affected by carburization of the bonding layer. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned problems by providing a method for controlling the crystal corrosion performance and mechanical strength of austenitic stainless steel composite plates.

[0007] The objective of this invention is achieved as follows: a method for controlling the intergranular corrosion performance and mechanical strength of austenitic stainless steel composite plates, comprising the following steps: Step 1: Controlling the properties and chemical composition of raw materials: the carbon content of austenitic stainless steel is controlled at 0-0.03%, the elongation of carbon steel plate is controlled at 25%-35%, the impact energy of carbon steel at 0℃ is controlled at 100J-300J, and the yield strength is controlled at 245-385MPa; Step 2: Controlling the production method: the explosive composite process uses ammonium nitrate oil explosive with a detonation velocity of 2200-2700m / s, and the heat treatment process uses a box-type resistance furnace, with the heat treatment temperature controlled at 570-670℃ and the heat treatment holding time at 1-1.5 hours. After heat treatment, the sample is removed from the furnace and air-cooled; Step 3: Improvement of the detection method: the intergranular corrosion test sample is thinned by 0.3-0.6mm according to the nominal thickness of the raw material. Before the test, the mating surfaces of the sample are sanded smooth with sandpaper to remove scratches, and the surface finish Ra≤1um is achieved. Then, the sample is degreased and dried before corrosion performance testing.

[0008] In step two, the heating rate of the heat treatment is controlled at 150-200℃ / h, and the cooling rate after exiting the furnace is controlled at 150-200℃ / h. The furnace is then removed from the furnace only after the temperature drops below 100℃.

[0009] The beneficial effects of this invention are: This method solves the problem of high-temperature tempering corrosion resistance in austenitic stainless steel composite plates. It meets the corrosion resistance requirements of some special austenitic stainless steel composite plates. It realizes a technical route where all austenitic stainless steel composite plates can be tempered at high temperatures. It meets the requirements of energy saving, consumption reduction, and environmental protection in composite plate production, and reduces the production cost of composite plates. It solves the problem of corrosion detection of composite plates being affected by carburization of the bonding layer. Detailed Implementation

[0010] This invention primarily addresses the problems of low elongation and decreased intergranular corrosion resistance in austenitic stainless steel composite plates during high-temperature tempering. It also solves the difficulties in processing the composite plates in later manufacturing equipment and addresses the issues of high yield strength and low elongation after high-temperature tempering. Furthermore, it meets customer requirements for corrosion resistance in composite plates made of certain special materials. Different heat treatment processes are developed based on the properties of different raw materials to meet the needs of composite plate production, improving the operability of high-temperature tempering for austenitic stainless steel composite plates. The method for controlling the crystal corrosion resistance and mechanical strength of austenitic stainless steel composite plates determines the method for detecting crystal corrosion by reducing the thickness of the bonding layer by 0.5 mm, meeting the requirements of energy saving, consumption reduction, and environmental protection in composite plate production. The main innovation lies in developing different heat treatment processes based on the properties of different raw materials to meet the needs of composite plate production. By controlling the chemical composition and properties of raw materials, the quality of composite plate products is improved and enhanced. Since the implementation of this invention patent, the bottleneck problem of reduced corrosion resistance of austenitic stainless steel composite plates when using high-temperature tempering process has been completely solved, reducing the heat treatment cost of composite plates and meeting the special requirements of special materials for composite plates.

[0011] The main contents of this invention are as follows: 1. Controlling the properties and chemical composition of raw materials: The carbon content of austenitic stainless steel is controlled at 0-0.03%, the elongation of carbon steel plates is 25%-35%, the impact energy of carbon steel at 0℃ is 100J-300J, and the yield strength is between 245-385MPa. 2. Controlling the production method: The explosive composite process uses ammonium nitrate oil explosive with a detonation velocity of 2200-2700m / s. The heat treatment process uses a box-type resistance furnace (RT3-2600-12). The heat treatment temperature is controlled at 570-670℃ according to the material and raw material properties. The heating rate above 300℃ and the heating and cooling rate are controlled at 150-200℃ / h. The product is then air-cooled after exiting the furnace. Different high-temperature tempering temperatures are determined experimentally for materials with different original properties. Finally, the intergranular corrosion resistance and mechanical properties of the composite plate are inspected. If the properties are qualified, a production method meeting the requirements is obtained. 3. Improvement of the testing method: The intergranular corrosion sample to be tested is thinned by 0.3-0.6 mm according to the nominal thickness of the raw material. Before the test, the mating surface of the sample is sanded smooth with sandpaper to remove scratches. The surface finish Ra≤1um is then removed, degreased and dried, and then the corrosion performance is tested according to the standard.

[0012] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention.

[0013] The austenitic stainless steel described in the method for controlling the crystal corrosion performance and mechanical strength of the austenitic stainless steel composite plate of the present invention is the material listed in GB24511.

[0014] 1. Control of raw material composition, cladding properties, and chemical composition: The carbon content of the cladding material is controlled at 0-0.03% for austenitic stainless steel; the elongation of the carbon steel plate is 25%-35%, the impact energy at 0℃ is 100J-300J, and the yield strength is between 245-385MPa. As is known in the art, the main challenges in controlling the corrosion resistance and mechanical properties of austenitic stainless steel cladding plates during high-temperature tempering heat treatment include: controlling the carbon content of the raw materials to ensure good corrosion resistance, as C content is a key factor directly affecting intergranular corrosion resistance. Experiments have shown that the strength of the product is directly related to the properties of the raw materials; therefore, controlling the properties of the raw materials can alter the mechanical properties of the final product.

[0015] 2. Production Method Control: The explosive composite process uses ammonium nitrate oil (ANFO) explosives with a detonation velocity of 2200-2700 m / s. The heat treatment process uses a box-type resistance furnace, with the heat treatment temperature controlled between 570-670℃ based on the material and raw material properties. Heating and cooling rates above 300℃ are 150-200℃ / h, followed by air cooling after furnace removal. For austenitic stainless steel composite plates with a thickness ≤20mm, improper heat treatment processes may compromise the product's plastic deformation capacity, leading to increased product strength that is detrimental to subsequent equipment manufacturing.

[0016] Experiments were conducted using different high-temperature tempering temperatures for materials with varying initial properties. Finally, the intergranular corrosion resistance and mechanical properties of the composite plate were tested. If the tests passed, a production method meeting the requirements could be obtained. 3. Testing method: When testing intergranular corrosion of composite plates, the effects of carburization of the bonding layer and polishing smoothness may cause some samples to produce false non-compliance results. Through experimental analysis, the influence range of carburization of the bonding layer was determined, and the affected area was removed to obtain the true test results. Example 1

[0017] Material: S30408+Q345R, thickness: 2+12mm.

[0018] The austenitic stainless steel composite plate cladding material S30408 ​​has a carbon content of 0.02%, while Q345R has a mechanical property of 28% elongation, 130J impact energy at 0℃, and a yield strength of 365MPa.

[0019] The explosive composite process uses ammonium nitrate oil explosive with a detonation velocity of 2350 m / s. The heat treatment process uses a box-type resistance furnace. The heat treatment temperature is controlled at 660℃ according to the material and raw material properties. The heating and cooling rate above 300℃ is 180℃ / h, and the furnace is air-cooled after exiting the furnace.

[0020] The intergranular corrosion test sample is thinned by 0.5 mm according to the nominal thickness of the raw material. Before the test, the mating surface of the sample is sanded smooth with sandpaper to remove scratches and the surface finish Ra is 0.7 μm. Then, it is degreased and dried, and then the corrosion performance is tested according to the standard.

[0021] The actual experimental results of high-temperature tempering heat treatment for different carbon contents and raw material mechanical properties are shown in the table below.

[0022]

[0023] It can be seen that, with the carbon content of the cladding material reduced and the mechanical properties of the raw materials controlled, the intergranular corrosion resistance and mechanical properties of the austenitic stainless steel composite plate are qualified. Example 2

[0024] Material: S31608+Q245R, thickness: 3+28mm.

[0025] The carbon content of the 31608 austenitic stainless steel composite plate cladding material is controlled at 0.02%, the elongation of Q245R is 29%, the impact energy of carbon steel at 0℃ is 140J, and the yield strength is 260MPa.

[0026] The explosive composite process uses ammonium nitrate oil explosive with a detonation velocity of 2400 m / s. The heat treatment process uses a box-type resistance furnace. The heat treatment temperature is controlled at 630℃ according to the material and raw material properties. The heating and cooling rate is 200℃ / h above 300℃, and the furnace is air-cooled after exiting the furnace.

[0027] The intergranular corrosion test sample is thinned by 0.5 mm according to the nominal thickness of the raw material. Before the test, the mating surface of the sample is sanded smooth with sandpaper to remove scratches and the surface finish Ra≤1um. Then, it is degreased and dried, and then the corrosion performance is tested according to the standard.

[0028] The actual experimental results of high-temperature tempering heat treatment for different carbon contents and raw material mechanical properties are shown in the table below.

[0029]

[0030] It can be seen that, with the carbon content of the cladding material reduced and the mechanical properties of the raw materials controlled, the intergranular corrosion resistance and mechanical properties of the austenitic stainless steel composite plate are qualified.

[0031] In summary, the present invention addresses the control method for austenitic stainless steel composite plates during high-temperature tempering heat treatment. By controlling the carbon content and mechanical properties of the raw materials, the requirements for qualified intergranular corrosion and qualified mechanical properties of the composite plates are achieved.

[0032] The above description is only a specific embodiment of the present invention, but the structural features protected by the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A method for controlling the grain corrosion properties and mechanical strength of austenitic stainless steel composite plates, characterized in that: Includes the following steps: Step 1: Control the properties and chemical composition of raw materials: The carbon content of austenitic stainless steel is controlled at 0-0.03%, the elongation of carbon steel plate is controlled at 25%-35%, the impact energy of carbon steel at 0℃ is controlled at 100J-300J, and the yield strength is controlled at 245-385MPa. Step 2: Controlling the production method: The explosive compounding process uses ammonium nitrate oil explosive with a detonation velocity of 2200-2700m / s. The heat treatment process uses a box-type resistance furnace, with the heat treatment temperature controlled at 570-670℃ and the heat treatment holding time at 1-1.5 hours. After the heat treatment is completed, the product is removed from the furnace and air-cooled. Step 3: Improvement of the detection method: The intergranular corrosion sample to be tested is thinned by 0.3-0.6 mm according to the nominal thickness of the raw material. Before the test, the mating surface of the sample is sanded smooth with sandpaper to remove scratches. The surface finish Ra≤1um is then removed and dried before corrosion performance testing. In step two, the heating rate of the heat treatment is controlled at 150-200℃ / h, and the cooling rate after exiting the furnace is controlled at 150-200℃ / h. The furnace is then removed from the furnace only after the temperature drops below 100℃.

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