Production method of hot-rolled copper-steel bimetal composite plate

Abstract

According to the production method of the hot-rolled copper-steel double-metal composite plate, copper is oxygen-free copper, and Cu is larger than or equal to 99.95%; the steel is low-alloy high-strength steel; the key process steps of the copper-steel composite plate comprise assembling, heating, rolling, cooling and finishing. By controlling the rolling temperature, the pass reduction rate, the cooling speed and other processes, the plate shape of the copper-steel rolled composite plate is obviously improved, the stability of the bonding surface is greatly improved, and therefore industrial production and application of the copper-steel bimetal rolled composite plate are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of rolling composite, and relates to a production method of a hot-rolled copper-steel bimetallic composite plate. Background Art

[0002] Copper-steel clad plates combine the properties of copper and steel, offering the electrical conductivity, thermal conductivity, and corrosion resistance of copper with the strength, toughness, and weldability of steel. They are a cost-effective, high-quality material widely used in the power, chemical, aerospace, and new energy equipment sectors. Compared to explosive cladding, rolled cladding is compatible with a wide range of metal materials and offers high production efficiency, low cost, high cladding precision, and safety and reliability.

[0003] However, due to the significant difference in ductility between copper and steel during rolling, the roll-bonding process can lead to severe deformation of the composite plate and cracking at the interface. Currently, existing technologies for copper-steel roll-bonding are rarely applied. Therefore, optimizing the copper-steel roll-bonding process to improve deformation uniformity and interfacial bonding efficiency during roll-bonding is of great technological significance. Summary of the Invention

[0004] The purpose of the present invention is to provide a production method of a hot-rolled copper-steel bimetallic composite plate. By controlling the rolling temperature, pass reduction rate, cooling rate and other processes, the plate shape of the copper-steel rolled composite plate is significantly improved and the stability of the bonding surface is greatly improved.

[0005] The technical solution of the present invention: A method for producing a hot-rolled copper-steel bimetallic composite plate, the process flow includes blanking - heating - rolling - cooling - finishing, the copper is oxygen-free copper, Cu ≥ 99.95%; the steel is low-alloy high-strength steel; the key process steps include: (1) Assembly: Use ABBA symmetrical assembly, where A is steel billet and B is copper billet; control the thickness ratio of A and B to be A / B = 1-3; apply isolation agent between the copper plates; then insert the steel billet seal along the circumference of the copper billet, weld and seal, and evacuate; (2) Heating: Heat the composite blank to 900~950℃ and keep it warm for 0.5 H min / mm and above, among which H is the thickness of the composite blank (mm), then control the furnace temperature to 950~1050℃, the heating time is within 10min, and make the temperature difference between the surface and the center of the composite blank when it comes out of the furnace be above 80℃, preferably, controlled at 100±10℃; (3) Rolling: Roll immediately after leaving the furnace, control the total reduction ratio ≥ 10; control the single pass reduction rate in % to be (8~15)+100(exp(△ T / T )-1), the pressing amount is limited to 40mm, of whichT and △ T are the average value and difference between the surface temperature and the center temperature of the rolling mill during rolling; T There are 3 to 5 rolling passes in the temperature range of 780 to 850°C; (4) Cooling: After rolling, the steel is accelerated to below 400°C. The cooling rate is expressed in °C / s. v 0+3lg h -2)~( v 0+3lg h -1) range, where v 0 is the air cooling speed (℃ / s), h is the thickness of the composite plate after rolling (mm); and then air-cooled to room temperature.

[0006] Furthermore, the low-alloy high-strength steel has a chemical composition percentage by mass of C≤0.22%, Si≤0.60%, Mn≤1.80%, P≤0.035%, S≤0.035%, Al=0.015%~0.080%, and may also include one or more elements of Nb≤0.11%, V≤0.13%, Ti≤0.05%, Cr≤1.0%, Mo≤0.30%, Ni≤0.80%, and Cu≤0.80%, with the balance being Fe and unavoidable impurities.

[0007] Furthermore, the low-alloy high-strength steel has a chemical composition mass percentage of C=0.06%~0.12%, Si=0.15~0.30%, Mn=1.45%~1.60%, P≤0.02%, S≤0.005%, Al=0.02%~0.05%, Ti=0.008%~0.02%, and the balance is Fe and unavoidable impurities; its tensile properties are: yield strength of 355~470MPa, tensile strength of 470~630MPa, and elongation of 20%~30%.

[0008] Furthermore, in step (4), the air cooling rate can be estimated based on the thickness of the composite plate according to the ambient temperature. When the ambient temperature is ≥10°C, the air cooling rate is 8.5 / s in °C / s. h 0.92 When the ambient temperature is less than 10℃, the air cooling rate is 9.0 / ℃ / s. h 0.92 .

[0009] Principle and innovation of the invention: Considering that the ductility of copper during hot rolling deformation is much higher than that of steel, the present invention controls the temperature of the composite billet surface to be high and the center temperature to be low through heating furnace temperature control to improve the extension of the steel billet layer, and at the same time controls the rolling reduction process with a large single-pass reduction rate when the temperature difference between the surface and the center of the composite billet is large and the rolling temperature is low to coordinate the deformation degree of steel and copper, so that even if a higher temperature and a large compression ratio rolling is used to improve the copper-steel bonding ratio, a rolled composite plate with a good plate shape can be obtained; considering that the thermal expansion coefficient of copper is larger than that of steel, it has a greater tendency to shrink during cooling, and the steel will undergo a supercooled austenite transformation during the cooling process and will produce a certain amount of expansion, the present invention adopts an accelerated cooling process and adjusts the cooling rate according to the thickness of the composite plate, so that the shrinkage of the steel outer layer and the copper inner layer of the rolled composite plate is appropriately matched, thereby reducing crack defects caused by thermal stress on the bonding surface.

[0010] The beneficial effects of the present invention are as follows: the copper-steel bimetallic rolled composite plate produced by the method of the present invention has a good plate shape, and at the same time, the interface bonding rate is stable, the bonding strength is high, and the residual stress is low, thereby realizing the industrial production of the copper-steel bimetallic rolled composite plate and promoting the promotion and application of the copper-steel composite plate. DETAILED DESCRIPTION

[0011] The following is further described by examples.

[0012] Example 1 A production method for a hot-rolled copper-steel bimetallic composite plate, the process flow comprising blanking, heating, rolling, cooling, and finishing. The copper is TU2, Cu ≥ 99.95%; the steel is Q355B low-alloy high-strength steel, and its chemical composition by weight percentage is C = 0.11%, Si = 0.20%, Mn = 1.50%, P = 0.015%, S = 0.003%, Al = 0.033%, Ti = 0.012%, and the balance is Fe and unavoidable impurities. The yield strength, tensile strength, and elongation of the copper-steel composite plate are 398 MPa, 546 MPa, and 26%. The key process steps of the copper-steel composite plate include: (1) Assembly: Use ABBA symmetrical assembly, where A is Q355B and B is TU2; control the thickness of Q355B to 100 mm and the thickness of TU2 to 50 mm, and the ratio is = 2; apply isolation agent between the copper plates; then insert the steel billet seal along the circumference of the copper billet, weld and seal, and evacuate; (2) Heating: Heat the composite blank to 930°C, keep it warm for 160 minutes, then control the furnace temperature to 950~1050°C, heating time is 5 minutes, so that the temperature difference between the surface and center of the composite blank is 100°C when it is taken out of the furnace; (3) Rolling: Rolling is performed immediately after the furnace is taken out, and the total reduction ratio is controlled to be 10; the reduction ratio of each pass is shown in Table 1. T There are five rolling passes in the temperature range of 780~850℃; (4) Cooling: After rolling, the steel is accelerated to below 400°C, with a cooling rate of about 3.0°C / s, where the ambient temperature is 20°C and the air cooling rate is v 0 is about 0.37℃ / s; then air-cool to room temperature.

[0013] Table 1 Rolling reduction rate of each pass in Example 1 ;

[0014] Example 2 A production method for a hot-rolled copper-steel bimetallic composite plate, the process flow comprising assembly, heating, rolling, cooling, and finishing. The copper is TU2, Cu ≥ 99.95%; the steel is Q355D low-alloy high-strength steel, and its chemical composition by weight percentage is C = 0.07%, Si = 0.22%, Mn = 1.55%, P = 0.012%, S = 0.002%, Al = 0.039%, Ti = 0.015%, and the balance is Fe and unavoidable impurities. The yield strength of the copper-steel composite plate is 365 MPa, the tensile strength is 500 MPa, and the elongation is 29%. The key process steps of the copper-steel composite plate include: (1) Assembly: Use ABBA symmetrical assembly, where A is Q355D and B is TU2; control the thickness of Q355D to 150mm and the thickness of TU2 to 60mm, with a ratio of =2.5; apply an isolation agent between the copper plates; then insert a steel billet seal along the circumference of the copper billet, weld and seal, and evacuate; (2) Heating: Heat the composite blank to 940°C, keep it warm for 240 minutes, then control the furnace temperature to 950~1050°C, and heat it for 8 minutes, so that the temperature difference between the surface and the center of the composite blank is 100°C when it is taken out of the furnace; (3) Rolling: Rolling is performed immediately after the furnace is taken out, and the total reduction ratio is controlled to be 10; the reduction ratio of each pass is shown in Table 2. T There are three rolling passes in the temperature range of 780~850℃; (4) Cooling: After rolling, the steel is cooled to below 400°C at an accelerated rate of about 3.5°C / s, with the ambient temperature at 0°C and the air cooling rate at v 0 is about 0.29℃ / s; then air-cool to room temperature.

[0015] Table 2 Rolling reduction rate of each pass in Example 2 ;

[0016] Example 3 A production method for a hot-rolled copper-steel bimetallic composite plate, the process flow comprising assembly, heating, rolling, cooling, and finishing. The copper is TU2, Cu≥99.95%; the steel is Q420ND low-alloy high-strength steel, and the chemical composition by weight percentage is C=0.18%, Si=0.35%, Mn=1.28%, P=0.018%, S=0.008%, Al=0.055%, Ti=0.018%, Nb=0.045%, V=0.061%, Cr=0.25%, Mo=0.10%, Ni=0.38%, and Cu=0.19%, with the remainder being Fe and unavoidable impurities. The yield strength of the copper-steel composite plate is 462 MPa, the tensile strength is 595 MPa, and the elongation is 21%. The key process steps of the copper-steel composite plate include: (1) Assembly: Use ABBA symmetrical assembly, where A is Q420ND and B is TU2; control the thickness of Q420ND to 60mm and the thickness of TU2 to 40mm, and the ratio is =1.5; apply isolation agent between the copper plates; then insert the steel billet seal along the circumference of the copper billet, weld and seal, and evacuate; (2) Heating: Heat the composite blank to 910°C, keep it warm for 120 minutes, then control the furnace temperature to 950~1050°C, and heat it for 4 minutes, so that the temperature difference between the surface and the center of the composite blank is 100°C when it is taken out of the furnace; (3) Rolling: Rolling is performed immediately after the furnace is taken out, and the total reduction ratio is controlled to be 10; the reduction ratio of each pass is shown in Table 3. T There are four rolling passes in the temperature range of 780~850℃; (4) Cooling: After rolling, the steel is cooled to below 400°C at an accelerated rate of about 4.0°C / s, with an ambient temperature of 15°C and an air cooling rate of v 0 is about 0.54℃ / s; then air-cool to room temperature.

[0017] Table 3 Rolling reduction rate of each pass in Example 3 .

Claims

1. A method for producing a hot-rolled copper-steel bimetallic composite plate, the process flow comprising assembling - heating - rolling - cooling - finishing, characterized in that: Copper is oxygen-free copper, Cu≥99.95%; The steel is low alloy high strength steel; The key process steps include: (1) Assembly: Use ABBA symmetrical assembly, where A is steel billet and B is copper billet; control the thickness ratio of A and B to be A / B = 1-3; apply isolation agent between the copper plates; then insert the steel billet seal along the circumference of the copper billet, weld and seal, and evacuate; (2) Heating: Heat the composite blank to 900~950℃ and keep it warm for 0.5 H min / mm and above, among which H is the thickness of the composite blank (mm), then control the furnace temperature to 950~1050℃, the heating time is within 10min, and the temperature difference between the surface and the center of the composite blank is above 80℃ when it comes out of the furnace; (3) Rolling: Roll immediately after leaving the furnace, control the total reduction ratio ≥ 10; control the single pass reduction rate in % to be (8~15)+100(exp(△ T / T )-1), the pressing amount is limited to 40mm, of which T and △ T are the average value and difference between the surface temperature and the center temperature of the rolling mill during rolling; T There are 3 to 5 rolling passes in the temperature range of 780 to 850°C; (4) Cooling: After rolling, the steel is accelerated to below 400°C. The cooling rate is expressed in °C / s. v 0+3lg h -2)~( v 0+3lg h -1) range, where v 0 is the air cooling speed (℃ / s), h is the thickness of the composite plate after rolling (mm); and then air-cooled to room temperature.

2. The method for producing a hot-rolled copper-steel bimetallic composite plate according to claim 1, wherein: The low-alloy high-strength steel has a chemical composition percentage by mass of C≤0.22%, Si≤0.60%, Mn≤1.80%, P≤0.035%, S≤0.035%, Al=0.015%~0.080%, and may further include one or more elements of Nb≤0.11%, V≤0.13%, Ti≤0.05%, Cr≤1.0%, Mo≤0.30%, Ni≤0.80%, and Cu≤0.80%, with the balance being Fe and unavoidable impurities.

3. The method for producing a hot-rolled copper-steel bimetallic composite plate according to claim 1, wherein: The low-alloy high-strength steel has a chemical composition percentage by mass of C=0.06%~0.12%, Si=0.15~0.30%, Mn=1.45%~1.60%, P≤0.02%, S≤0.005%, Al=0.02%~0.05%, Ti=0.008%~0.02%, and the balance is Fe and unavoidable impurities; its tensile properties are a yield strength of 355~470MPa, a tensile strength of 470~630MPa, and an elongation of 20%~30%.

4. The method for producing a hot-rolled copper-steel bimetallic composite plate according to claim 1, wherein: Process step (2) Heating process: Control the temperature difference between the surface and center of the composite blank at 100±10℃ when it comes out of the furnace.

5. The method for producing a hot-rolled copper-steel bimetallic composite plate according to claim 1, characterized in that: Process step (4): The air cooling rate is determined by the thickness of the composite plate according to the ambient temperature. When the ambient temperature is ≥10°C, the air cooling rate is 8.5 / s in °C / s. h 0.92 ; When the ambient temperature is less than 10℃, the air cooling rate is 9.0 / ℃ / s. h 0.92 .