A production method of hot-rolled copper-steel bimetallic composite plate

Abstract

The application discloses a production method of a hot-rolled copper-steel bimetal composite plate, wherein copper is oxygen-free copper with Cu being greater than or equal to 99.95%, and steel is low-alloy high-strength steel; key process steps of the copper-steel composite plate include grouping, heating, rolling, cooling and finishing; the copper-steel rolling composite plate is obviously improved in shape by controlling rolling temperature, pass reduction rate and cooling speed and the like, and the stability of the joint surface is greatly improved, so that the industrial production and application of the copper-steel bimetal rolling composite plate are realized.

Description

Technical Field

[0001] This invention belongs to the field of rolling composite technology and relates to a method for producing hot-rolled copper-steel bimetallic composite plates. Background Technology

[0002] Copper-steel composite plates combine the properties of both copper and steel. They possess the electrical and thermal conductivity and corrosion resistance of copper, while also exhibiting the strength, toughness, and weldability of steel. This makes them a high-quality, cost-effective material widely used in power, chemical, aerospace, and new energy equipment industries. Compared to explosive bonding, rolling bonding is compatible with a variety of metal materials and offers advantages such as high production efficiency, low cost, high bonding precision, and safety and reliability.

[0003] However, due to the significant difference in ductility between copper and steel during rolling, the rolling composite process can lead to severe deformation of the composite plate and cracking at the interface. Currently, existing technologies rarely apply to copper-steel rolling composites. Therefore, optimizing the copper-steel rolling composite preparation process and improving the deformation uniformity and interface bonding rate during copper-steel rolling composites is of significant technological advancement importance. Summary of the Invention

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

[0005] The technical solution of the present invention:

[0006] A method for producing hot-rolled copper-steel bimetallic composite plates, the process flow of which includes billet assembly, heating, rolling, cooling, and finishing, wherein the copper is oxygen-free copper with Cu≥99.95%; and the steel is low-alloy high-strength steel; key process steps include:

[0007] (1) Billet assembly: ABBA symmetrical billet assembly is adopted, where A is steel billet and B is copper billet; the thickness ratio of A and B is controlled as A / B=1~3; a release agent is applied between the copper plates; then steel billet sealing strips are inserted along the circumference of the copper billet, welded and sealed and vacuumed.

[0008] (2) Heating: Heat the composite blank to 900~950℃ and hold for 0.5 hours. H ·min / mm or above, of which H The thickness of the composite billet is (mm), and then the furnace temperature is controlled to 950~1050℃, and the heating time is within 10 minutes, so that the temperature difference between the surface and the center of the composite billet is above 80℃ when it is taken out of the furnace, preferably controlled at 100±10℃.

[0009] (3) Rolling: Roll immediately after exiting the furnace, and control the total compression ratio ≥10; control the single-pass reduction rate as (8~15)+100(exp(△T / T )-1), reduction is limited to 40mm, wherein T and△ T are the average value and difference of the slab surface temperature and center temperature during rolling, respectively, in ℃; control T 3-5 passes of rolling in the temperature range of 780-850℃;

[0010] (4) cooling: accelerated cooling to below 400℃ after rolling, cooling speed is in the range of ( v 0+3lg h -2)~( v 0+3lg h -1) in ℃ / s, wherein v 0 is the air cooling speed (℃ / s), h is the thickness of the clad plate after rolling (mm); then air cooling to room temperature.

[0011] Further, the low-alloy high-strength steel has a chemical composition with mass percentage of C≤0.22%, Si≤0.60%, Mn≤1.80%, P≤0.035%, S≤0.035%, Al=0.015%-0.080%, and one or more of Nb≤0.11%, V≤0.13%, Ti≤0.05%, Cr≤1.0%, Mo≤0.30%, Ni≤0.80%, Cu≤0.80%, and the balance of Fe and inevitable impurities.

[0012] Further, the low-alloy high-strength steel has a chemical composition with 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 of Fe and inevitable impurities; and the tensile properties are: yield strength of 355-470 MPa, tensile strength of 470-630 MPa, and elongation of 20%-30%.

[0013] Further, in step (4), the air cooling speed can be estimated from the thickness of the clad plate according to the ambient temperature, when the ambient temperature≥10℃, the air cooling speed is 8.5 / h 0.92 ℃ / s; when the ambient temperature<10℃, the air cooling speed is 9.0 / h 0.92 ℃ / s.

[0014] Invention principle and innovation: considering that the ductility of copper is much higher than that of steel during hot rolling, the surface temperature of the composite blank is high and the center temperature is low by controlling the heating furnace temperature to improve the elongation of the steel blank layer, and the rolling reduction process is controlled when the temperature difference between the surface and the center of the composite blank is large and the rolling temperature is low, and the single pass reduction rate is large, so as to coordinate the deformation degree of steel and copper, so that even if higher temperature and large compression ratio rolling is adopted, it is beneficial to improve the copper-steel bonding rate, and good plate shape of the rolled composite plate can be obtained; considering that the thermal expansion coefficient of copper is larger than that of steel, and there is a greater shrinkage tendency during cooling, and the steel will produce a certain expansion during the transformation of supercooled austenite during cooling, the accelerated cooling process is adopted in the application, and the cooling speed is adjusted according to the thickness of the composite plate, so that the shrinkage of the outer layer of steel and the inner layer of copper of the rolled composite plate is matched appropriately, so as to reduce the crack defects caused by thermal stress of the bonding surface.

[0015] The copper-steel bimetallic rolled composite plate produced by the method has good plate shape, stable interface bonding rate, high bonding strength and low residual stress, so that the industrial production of the copper-steel bimetallic rolled composite plate is realized, and the popularization and application of the copper-steel composite plate are promoted. DETAILED DESCRIPTION

[0016] The following is further illustrated by examples. Example 1

[0017] A production method of a hot-rolled copper-steel bimetallic composite plate, the process flow includes blanking, heating, rolling, cooling and finishing, the copper is TU2, Cu≥99.95%; the steel is Q355B low alloy high strength steel, the chemical composition mass percentage is C=0.11%, Si=0.20%, Mn=1.50%, P=0.015%, S=0.003%, Al=0.033%, Ti=0.012%, the balance is Fe and inevitable impurities; the yield strength is 398MPa, the tensile strength is 546MPa, and the elongation is 26%; the key process steps of the copper-steel composite plate include:

[0018] (1) blanking: ABBA symmetric blanking is adopted, wherein A is Q355B and B is TU2; the thickness of Q355B is controlled to be 100mm, the thickness of TU2 is 50mm, and the ratio is =2; the isolation agent is coated between the copper plates; then the steel blank is inserted into the sealing strip along the circumference of the copper blank, welded and sealed, and vacuumized;

[0019] (2) heating: the composite blank is heated to 930℃, and the temperature is kept for 160min, then the furnace temperature is controlled to 950~1050℃, and the heating time is 5min, so that the temperature difference between the surface and the center of the composite blank is 100℃ when it is discharged;

[0020] (3) Rolling: immediately after the furnace, the total compression ratio is controlled to be 10; the reduction rate of each pass is shown in Table 1, which can be seen T There are 5 passes of rolling in the temperature range of 780-850℃;

[0021] (4) Cooling: after rolling, accelerated cooling is performed to below 400℃, and the cooling speed is about 3.0℃ / s, wherein the ambient temperature is 20℃, and the air cooling speed v 0 is about 0.37℃ / s; then air cooling is performed to room temperature.

[0022] Table 1 Reduction rate of each pass of rolling in Example 1

[0023] .

[0024] Example 2

[0025] A production method of a hot-rolled copper-steel bimetallic composite plate, the process flow comprises blanking, heating, rolling, cooling and finishing, the copper is TU2, Cu≥99.95%; the steel is Q355D low-alloy high-strength steel, the mass percentage of its chemical components 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 inevitable impurities; the yield strength thereof is 365MPa, the tensile strength is 500MPa, and the elongation is 29%; the key process steps of the copper-steel composite plate comprise:

[0026] (1) Blanking: ABBA symmetric blanking is adopted, wherein A is Q355D and B is TU2; the thickness of Q355D is controlled to be 150mm, and the thickness of TU2 is 60mm, and the ratio is =2.5; an isolation agent is coated between the copper plates; then a steel blank seal is inserted into the copper blank along the circumference, and the seal is welded and vacuumized;

[0027] (2) Heating: the composite blank is heated to 940℃ and kept for 240min, and then the furnace temperature is controlled to be 950-1050℃, and the heating time is 8min, so that the temperature difference between the surface and the center of the composite blank when discharged is 100℃;

[0028] (3) Rolling: immediately after the furnace, the total compression ratio is controlled to be 10; the reduction rate of each pass is shown in Table 2, which can be seen T There are 3 passes of rolling in the temperature range of 780-850℃;

[0029] (4) Cooling: after rolling, accelerated cooling is performed to below 400℃, and the cooling speed is about 3.5℃ / s, wherein the ambient temperature is 0℃, and the air cooling speed v 0 is about 0.29℃ / s; then air cooling is performed to room temperature.

[0030] Table 2 Reduction rate of each pass of rolling in Example 2

[0031] .

[0032] Example 3

[0033] A production method of hot-rolled copper-steel bimetallic composite plate, the process flow includes assembling, heating, rolling, cooling and finishing, the copper is TU2, Cu≥99.95%; the steel is Q420ND low alloy high strength steel, the chemical composition mass 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%, Cu=0.19%, the balance is Fe and inevitable impurities; the yield strength 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:

[0034] (1) Assembling: ABBA symmetry assembling is adopted, wherein A is Q420ND and B is TU2; the thickness of Q420ND is controlled to be 60 mm, the thickness of TU2 is controlled to be 40 mm, and the ratio is =1.5; isolation agent is coated between the copper plates; then steel blank sealing strip is inserted along the circumference of the copper blank, welded and sealed, and vacuumized;

[0035] (2) Heating: the composite blank is heated to 910℃ and kept for 120 min, then the furnace temperature is controlled to 950~1050℃, and the heating time is 4 min, so that the temperature difference between the surface and the center of the composite blank when discharged is 100℃;

[0036] (3) Rolling: immediately after discharging, the total compression ratio is controlled to be 10; the pass reduction rate is shown in Table 3, which can be seen that T there are 4 passes of rolling in the temperature range of 780~850℃;

[0037] (4) Cooling: after rolling, accelerated cooling is performed to below 400℃, and the cooling speed is about 4.0℃ / s, wherein the ambient temperature is 15℃, and the air cooling speed v is about 0.54℃ / s; then air cooling is performed to room temperature.

[0038] Table 3 Rolling pass reduction rate of Example 3

[0039] .

Claims

1. A production method of hot-rolled copper-steel bimetallic composite plate, the process flow comprising assembling - heating - rolling - cooling - finishing, characterized in that: The copper is oxygen-free copper, Cu≥99.95%; The steel is low-alloy high-strength steel; The key process steps include: (1) blank assembly: ABBA symmetric blank assembly is adopted, wherein A is steel blank and B is copper blank; the thickness ratio of A and B is controlled as A / B=1-3; isolation agent is coated between copper plates; then steel blank seal is inserted into the copper blank circumferentially, welded and sealed, and vacuumized; (2) Heating: heating the composite blank to 900-950°C, holding time is 0.5 H • min / mm or more, wherein H is the thickness of the composite blank (mm), and then controlling the furnace temperature to 950-1050°C, heating time is within 10 min, so that the surface and center temperature difference of the composite blank when discharged is 80°C or more; (3) Rolling: immediately after tapping, control the total compression ratio ≥ 10; control the single pass reduction rate in % (8~15)+100(exp(△ T / T )-1), the reduction amount is limited to 40mm, wherein T and△ T are the average value °C and difference °C of the slab surface temperature and center temperature during rolling; control T 3~5 passes of rolling in the temperature range of 780~850℃; (4) cooling: accelerated cooling to below 400°C after rolling, the cooling rate being in the range of 0+3lg v -2) (°C / s), h v 0+3lg h -1) (°C / s), v 0 being the air cooling rate (°C / s), h being the thickness of the composite plate after rolling (mm); and then air cooling to room temperature.​ 2. The method of claim 1, wherein the hot-rolled copper-steel bimetallic composite plate is produced by the steps of: The low-alloy high-strength steel has the following chemical component mass percentage: C≤0.22%, Si≤0.60%, Mn≤1.80%, P≤0.035%, S≤0.035%, Al=0.015%-0.080%, and one or more of the following elements: Nb≤0.11%, V≤0.13%, Ti≤0.05%, Cr≤1.0%, Mo≤0.30%, Ni≤0.80%, Cu≤0.80%, and the balance of Fe and inevitable impurities. ​ 3. The method of claim 1, wherein the hot-rolled copper-steel bimetallic composite plate is produced by the steps of: The low-alloy high-strength steel has the following chemical component mass percentage: 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 of Fe and inevitable impurities; and the tensile properties are as follows: yield strength 355-470 MPa, tensile strength 470-630 MPa, and elongation 20%-30%. ​ 4. The method for producing a hot-rolled copper-steel bimetallic composite plate according to claim 1, characterized in that, Process step (2) heating process: the surface and center temperature difference of the composite blank when discharged is controlled as 100±10℃.

5. The method of claim 1, wherein the hot-rolled copper-steel bimetallic composite plate is produced by the steps of: Process step (4): The air cooling speed is determined by the composite plate thickness according to the ambient temperature, when the ambient temperature is ≥10℃, the air cooling speed is 8.5 °C / s h 0.92 ; When the ambient temperature is < 10°C, the air cooling speed is 9.0 °C / s h 0.92 .