Production method of nickel-based alloy composite board

Abstract

The invention relates to a production method of a nickel-based alloy composite board, a base material is steel SA516Gr.70N for a pressure vessel, a covering material is nickel-based alloy UNS N08825, the thickness of the produced composite board is 25-60mm, and the production method adopts a process route of blank assembly, composite blank heating, controlled rolling and controlled cooling and heat treatment. The composite board produced by the method has the binding rate of 100% and good delivery state and simulated postweld heat treatment state performance: the shear strength is greater than or equal to 330 MPa, the yield strength Rp0.2 is greater than or equal to 260 MPa, the tensile strength Rm is 485-620 MPa, the elongation (gauge length of 50 mm) A is greater than or equal to 21%, the-52 DEG C low-temperature impact absorption energy is greater than or equal to 60 J, the average coating intergranular corrosion rate is less than or equal to 0.457 mm / y, and the average spot corrosion rate is less than or equal to 0.4 g / m < 2 >; and the technical requirements of the nickel-based alloy composite plate for the pressure vessel are completely met.

Description

Technical Field

[0001] This invention belongs to the field of composite plate manufacturing technology, and relates to a method for producing nickel-based alloy composite plates, particularly nickel-based alloy composite plates suitable for pressure vessels. Background Technology

[0002] Nickel-based alloys possess excellent high-temperature resistance and corrosion resistance, playing an irreplaceable role in harsh industrial environments. Nickel-based 825 alloy, a titanium-stabilized nickel-iron-chromium alloy with added molybdenum and copper, exhibits excellent corrosion resistance to both reducing and oxidizing media. However, the high cost of pure nickel-based 825 alloy materials severely limits its widespread application. To resolve the contradiction between cost and performance, composite plates of nickel-based 825 alloy and carbon steel or low-alloy steel have emerged. Currently, the mainstream composite methods are explosive bonding or rolling bonding, which firmly bond a thin layer of nickel-based 825 alloy (cladding) to a thicker layer of ordinary carbon steel or low-alloy steel (base layer), forming a "bimetallic" plate. This structure ensures that the cladding in contact with corrosive media possesses the excellent corrosion resistance of nickel-based 825 alloy, while utilizing the excellent mechanical properties provided by the base material. This significantly reduces material costs while effectively meeting application requirements.

[0003] Previously, nickel-based alloy composite plates were mainly produced using explosive bonding. However, due to the low production efficiency, high cost, significant environmental impact, and poor surface quality and shape of explosive bonding, rolling bonding is gradually being adopted for production. Because carbon steel and nickel-based alloys differ significantly in their coefficients of thermal expansion, thermal conductivity, and high-temperature strength, poor bonding and low shear strength are common in nickel-based alloy composite plates. Furthermore, because the composite plate remains within the sensitization temperature range of nickel-based 825 alloy for extended periods during the rolling bonding process, the corrosion resistance of the nickel-based 825 alloy coating can easily decrease, or even fail, failing to meet application requirements. Summary of the Invention

[0004] The purpose of this invention is to provide a method for producing nickel-based alloy composite plates, particularly suitable for pressure vessels, to obtain nickel-based alloy composite plates for pressure vessels with a bonding rate of 100%, shear strength ≥330MPa, and mechanical properties of the substrate and corrosion resistance of the cladding material that meet the technical requirements.

[0005] The technical solution of the present invention: A method for producing a nickel-based alloy composite plate. The produced composite plate has a thickness of 25-60 mm. The base material is pressure vessel steel SA516Gr.70N, with a chemical composition by mass percentage of C≤0.18%, Si: 0.15%-0.40%, Mn: 0.85%-1.50%, P≤0.010%, S≤0.003%, Al: 0.020%-0.050%, Nb≤0.02%, V≤0.03%, Ti≤0.03%, Cr≤0.30%, Mo≤0.12%, Ni≤0.40%, Cu≤0.40%, B≤0.0010%, and the balance being Fe and unavoidable impurities. The cladding material is a nickel-based alloy UNS. N08825 has the following chemical composition by mass percentage: Ni: 38.0%–46.0%, Cr: 19.5%–23.5%, Fe ≥ 22.0%, Mn ≤ 1.0%, C ≤ 0.05%, Cu: 1.5%–3.0%, Si ≤ 0.5%, S ≤ 0.03%, Al ≤ 0.2%, Ti: 0.6%–1.2%, Mo: 2.5%–3.5%, with the balance being unavoidable impurities. The process steps include: (1) Assembly: First, clean the iron oxide scale, oil stains, foreign matter and surface defects on the surface of the base material pressure vessel steel SA516Gr.70N and the cladding material nickel-based alloy UNS N08825. Then, apply a release agent evenly to the contact surface between the cladding materials and dry it. The base material → cladding material → cladding material → base material are stacked from bottom to top in a symmetrical assembly method. Then, the composite billet is welded and sealed around by gas shielded welding + submerged arc welding and vacuum treatment. The vacuum degree is ≤0.01Pa and the vacuum time is ≥90 minutes to remove the gas in the composite billet. (2) Composite billet heating: Based on the characteristic that the thermal conductivity of nickel-based alloy N08825 is much smaller than that of pressure vessel steel SA516Gr.70N, in order to ensure that nickel-based alloy N08825 is fully dissolved and to limit the grain growth of the base material and the cladding, the composite billet is heated by low temperature heating + short time heat preservation, limiting the furnace temperature to ≤1180℃, and the tapping temperature is controlled at 1150~1180℃. The heating time in the furnace is calculated according to the thickness of the composite billet (mm) as [(1.1~1.5)×H1+(5.0~5.4)×H2] min / mm, where H1 and H2 are the thickness of the base layer and the cladding layer (mm), respectively, to ensure uniform heating of the composite billet; (3) Controlled rolling and controlled cooling: High temperature large reduction + low temperature small reduction + controlled cooling method is adopted. In the high temperature controlled rolling stage at a temperature ≥1000℃, a large reduction system is adopted to ensure that the reduction amount in at least 4 passes is ≥38mm or the reduction rate is ≥18%; in the temperature <1000℃, a multi-pass small reduction system is adopted, with a single pass reduction rate ≤10% and a final rolling temperature ≥900℃; after rolling, ACC cooling is carried out directly, and the red temperature is controlled at 680~720℃ to reduce the sensitization of the nickel-based alloy N08825 of the cladding material; (4) Heat treatment: Before heat treatment, the composite plate is put into the furnace in a double-layer manner without being separated. In order to reduce the residence time of the cladding nickel-based alloy N08825 in the sensitization temperature range, a heat treatment method of rapid heating + short-time holding + high-temperature rapid cooling is adopted. The normalizing temperature is 910±10℃, the heating rate is 1.4~1.8 min / mm, the holding time is 10~30min, and after taking it out of the furnace, it is rapidly cooled by NCC equipment or quenching machine. The red temperature is controlled at 680~720℃.

[0006] The main innovations of this invention are as follows: The composite billet heating method employs low-temperature heating followed by short-time holding, ensuring sufficient solid solution of the nickel-based alloy coating and inhibiting grain growth in both the coating and substrate, thus guaranteeing uniform temperature throughout the composite billet. The composite billet rolling process utilizes a combination of high-temperature high-reduction rolling, low-temperature low-reduction rolling, and controlled cooling. High-temperature high-reduction rolling achieves a good bond between the substrate and coating, while low-temperature low-reduction rolling reduces deformation stress caused by the significant differences in high-temperature strength and plasticity between the coating and substrate, thereby reducing stress between the bonding layers and preventing localized poor bonding due to excessive stress. Rapid cooling after rolling primarily aims to reduce the residence time of the nickel-based alloy coating in the sensitization temperature range, improving the corrosion resistance of the nickel-based alloy. The composite plate heat treatment employs a rapid heating + short-time holding + high-temperature rapid cooling method, reducing the residence time of the nickel-based alloy coating in the sensitization temperature range, improving the corrosion resistance of the nickel-based alloy while refining the substrate grains, increasing the substrate strength, and enhancing its low-temperature impact toughness.

[0007] The beneficial effects of the present invention are as follows: the nickel-based alloy composite plate for pressure vessels produced by the method of the present invention has a bonding rate of 100%, a shear strength of ≥330MPa, and the mechanical properties of the substrate and the corrosion resistance of the cladding material all meet the technical requirements for nickel-based alloy composite plates for pressure vessels. Detailed Implementation

[0008] The present invention will be further described below with reference to the embodiments. Example 1

[0009] A method for producing a nickel-based alloy composite plate, particularly suitable for pressure vessels, wherein the produced composite plate has a thickness of (37+3) mm, the base material is pressure vessel steel SA516Gr.70N, and the chemical composition by mass percentage is C=0.15%, Si=0.32%, Mn=1.45%, P=0.009%, S=0.0015%, Al=0.036%, Nb=0.016%, V=0.026%, Ti=0.015%, Cr=0.03%, Mo=0.01%, Ni=0.02%, Cu≤0.02%, B=0.0006%, with the balance being Fe and unavoidable impurities; the cladding material is a nickel-based alloy UNS. N08825 has the following chemical composition by mass percentage: Ni=38.4%, Cr=22.7%, Fe=31.4%, Mn=0.7%, C=0.01%, Cu=1.9%, Si=0.3%, S=0.002%, Al=0.1%, Ti=0.8%, Mo=3.1%, with the balance being unavoidable impurities. Key process steps include: (1) Billet assembly: Select two billets each of base material pressure vessel steel SA516Gr.70N and cladding material nickel-based alloy UNS N08825. The base material SA516Gr.70N has a thickness of 188mm × width of 2150mm × length of 2280mm, and the cladding material UNS N08825 has a thickness of 15mm × width of 2050mm × length of 2180mm. The composite billet after assembly has a thickness of 406mm × width of 2150mm × length of 2280mm. First, clean the iron oxide scale, oil stains, foreign matter and surface defects on the surface of the pressure vessel base material SA516Gr.70N and the nickel-based alloy cladding UNS N08825. Then, evenly apply a release agent to the contact surface between the cladding materials and dry it. The base material → cladding material → cladding material → base material are stacked in a symmetrical assembly method from bottom to top. Then, the composite billet is welded and sealed around the perimeter using gas shielded welding + submerged arc welding and vacuum treatment. The vacuum degree is 0.01Pa and the vacuum time is 100 minutes. (2) Composite billet heating: The composite billet is heated by low temperature heating + short time heat preservation, limiting the furnace temperature to 1180℃, the actual tapping temperature to 1165℃, and the heating time in the furnace is 644min. (3) Controlled rolling and cooling: The rolling temperature is ≥1000℃, the reduction of the first 4 passes is 41mm, 41mm, 41mm and 41mm respectively; when the rolling temperature is <1000℃, the reduction rate of each pass is within 10% and the final rolling temperature is 933℃; after rolling, the rolling temperature is directly entered into ACC cooling and the red temperature is 698℃. (4) Heat treatment: Before heat treatment, the composite board is not separated and is put into the furnace in a double-layer manner. The heat treatment method is rapid heating + short-time heat preservation + high temperature rapid cooling. The furnace temperature is set at 910℃, the actual furnace exit temperature is 904℃, the furnace time is 143 minutes, and after exiting the furnace, the high temperature zone is rapidly cooled by a quenching machine, and the red temperature is 692℃.

[0010] The (37+3) mm thick SA516Gr.70N+UNS N08825 composite board produced in Example 1 has a 100% bonding rate, high shear strength, and good mechanical properties of the substrate and corrosion resistance of the coating. The mechanical properties of the substrate and the corrosion resistance of the coating are shown in Table 1. The sample mold welding heat treatment process was as follows: the holding temperature was 620±10℃, and the holding time was 9 hours.

[0011] Table 1-1 Mechanical properties of the base layer and corrosion resistance of the coating of the composite board in Example 1 .

[0012] Table 1-2 Mechanical properties of the base layer and corrosion resistance of the coating of the composite board in Example 1 . Example 2

[0013] A method for producing a nickel-based alloy composite plate, particularly suitable for pressure vessels, wherein the produced composite plate has a thickness of (56+4) mm, the base material is pressure vessel steel SA516Gr.70N, and the chemical composition by mass percentage is C=0.14%, Si=0.28%, Mn=1.46%, P=0.0077%, S=0.0012%, Al=0.034%, Nb=0.016%, V=0.025%, Ti=0.003%, Cr=0.04%, Mo=0.01%, Ni=0.27%, Cu=0.26%, B=0.0004%, with the balance being Fe and unavoidable impurities; the cladding material is a nickel-based alloy UNS. N08825 has the following chemical composition by mass percentage: Ni=38.4%, Cr=22.7%, Fe=31.4%, Mn=0.7%, C=0.01%, Cu=1.9%, Si=0.3%, S=0.002%, Al=0.1%, Ti=0.8%, Mo=3.1%, with the balance being unavoidable impurities. Key process steps include: (1) Billet assembly: Select two billets each of base material pressure vessel steel SA516Gr.70N and cladding material nickel-based alloy UNS N08825. The base material SA516Gr.70N has a size of 226mm thick × 2180mm wide × 2700mm long, and the cladding material UNS N08825 has a size of 15mm thick × 2080mm wide × 2600mm long. The composite billet after assembly has a size of 450mm thick × 2180mm wide × 2700mm long. First, clean the iron oxide scale, oil stains, foreign matter and surface defects on the surface of the pressure vessel base material SA516Gr.70N and the nickel-based alloy cladding UNS N08825. Then, evenly apply a release agent to the contact surface between the cladding materials and dry it. The base material → cladding material → cladding material → base material are stacked in a symmetrical assembly method from bottom to top. Then, the composite billet is welded and sealed around the perimeter using gas shielded welding + submerged arc welding and vacuum treatment. The vacuum degree is 0.01Pa and the vacuum time is 120 minutes. (2) Composite billet heating: The composite billet is heated by low temperature heating + short time heat preservation, limiting the furnace temperature to 1180℃, the actual tapping temperature to 1162℃, and the heating time in the furnace is 753min; (3) Controlled rolling and cooling: The rolling temperature is ≥1000℃, the reduction of the first 4 passes is 40mm, 41mm, 41mm and 40mm respectively; when the rolling temperature is <1000℃, the reduction rate of each pass is within 10% and the final rolling temperature is 951℃; after rolling, the rolling temperature is directly entered into ACC cooling and the red temperature is 706℃. (4) Heat treatment: Before heat treatment, the composite board is not separated and is put into the furnace in a double-layer manner. The heat treatment method is rapid heating + short-time heat preservation + high temperature rapid cooling. The furnace temperature is set at 910℃, the actual furnace exit temperature is 903℃, the furnace time is 194 minutes, and after exiting the furnace, the high temperature zone is rapidly cooled by a quenching machine, and the red temperature is 702℃.

[0014] The (56+4) mm thick SA516Gr.70N+UNS N08825 composite board produced in Example 2 has a 100% bonding rate, high shear strength, and good mechanical properties of the substrate and corrosion resistance of the coating. The mechanical properties of the substrate and the corrosion resistance of the coating are shown in Table 2. The sample mold welding heat treatment process was as follows: the holding temperature was 620±10℃, and the holding time was 9 hours.

[0015] Table 2-1 Mechanical properties of the base layer and corrosion resistance of the coating of the composite board in Example 2 .

[0016] Table 2-2 Mechanical properties of the base layer and corrosion resistance of the coating of the composite board in Example 2 .

[0017] As can be seen from the results of Examples 1 and 2, the nickel-based alloy composite plate for pressure vessels produced by the method of the present invention has a 100% bonding rate, high shear strength, and the mechanical properties of the substrate and the corrosion resistance of the cladding material all meet the technical requirements for nickel-based alloy composite plates for pressure vessels.

Claims

1. A method of producing a nickel-based alloy clad plate, characterized by: The produced composite panels have a thickness of 25–60 mm. The base material is pressure vessel steel SA516Gr.70N, with the following chemical composition by mass percentage: C≤0.18%, Si: 0.15%–0.40%, Mn: 0.85%–1.50%, P≤0.010%, S≤0.003%, Al: 0.020%–0.050%, Nb≤0.02%, V≤0.03%, Ti≤0.03%, Cr≤0.30%, Mo≤0.12%, Ni≤0.40%, Cu≤0.40%, B≤0.0010%, with the balance being Fe and unavoidable impurities. The cladding material is a nickel-based alloy UNS. N08825 has the following chemical composition by mass percentage: Ni: 38.0%–46.0%, Cr: 19.5%–23.5%, Fe ≥ 22.0%, Mn ≤ 1.0%, C ≤ 0.05%, Cu: 1.5%–3.0%, Si ≤ 0.5%, S ≤ 0.03%, Al ≤ 0.2%, Ti: 0.6%–1.2%, Mo: 2.5%–3.5%, with the balance being unavoidable impurities. The process steps include: (1) Assembly: Clean the surfaces of the substrate and the cladding material, apply release agent evenly to the contact surface between the cladding materials and dry it, and stack the substrate → cladding material → cladding material → substrate in a symmetrical assembly method from bottom to top. Then, weld and seal the perimeter of the composite blank by gas shielded welding + submerged arc welding and vacuum treatment. The vacuum degree is ≤0.01Pa and the vacuum time is ≥90 minutes. (2) Heating of composite billet: Low temperature heating + short time heat preservation is adopted to limit the furnace temperature to ≤1180℃ and the tapping temperature to 1150~1180℃. The heating time in the furnace is calculated according to the thickness of the composite billet (mm) as [(1.1~1.5)×H1+(5.0~5.4)×H2] min / mm, where H1 and H2 are the thickness of the base layer and the cladding layer (mm) respectively, to ensure uniform heating of the composite billet; (3) Controlled rolling and controlled cooling: High temperature large reduction + low temperature small reduction + controlled cooling are adopted. In the high temperature controlled rolling stage with a temperature ≥1000℃, a large reduction system is adopted to ensure that the reduction amount in at least 4 passes is ≥38mm or the reduction rate is ≥18%; in the temperature <1000℃, a multi-pass small reduction system is adopted, with a single pass reduction rate ≤10% and a final rolling temperature ≥900℃; after rolling, ACC cooling is carried out directly, and the red temperature is controlled at 680~720℃. (4) Heat treatment: Before heat treatment, the composite board is put into the furnace in a double layer without being separated. The heat treatment method is rapid heating + short-time heat preservation + high temperature rapid cooling. The austenitizing temperature is 910±10℃, the heating rate is 1.4~1.8 min / mm, the heat preservation time is 10~30min, and after taking it out of the furnace, it is rapidly cooled by NCC equipment or quenching machine. The red temperature is controlled at 680~720℃.