Production method of T2+Q355B copper steel rolled composite plate

Abstract

The invention discloses a production method of a T2+Q355B copper steel rolled composite plate. The technological process comprises the steps of assembling, heating, rolling, stack cooling, finishing, flaw detection and warehousing. A T2 + Q355B copper steel rolled composite plate with excellent bonding strength, mechanical property and conductivity is obtained by adopting a vacuum rolling composite technology, a symmetric assembly technology and a low-speed deformation technology and utilizing wide and thick plate production line equipment and technical advantages, the thickness of a base material ranges from 5 mm to 40 mm, the thickness of a composite layer ranges from 1 mm to 20 mm, the width is smaller than or equal to 3600 mm, the yield strength is larger than or equal to 250 Mpa, the tensile strength ranges from 350 Mpa to 600 Mpa, the shear strength is larger than or equal to 120 Mpa, and the composite layer T2 copper conductivity IACS is larger than or equal to 85%. The intergranular corrosion crack rate is 0. The product can be widely applied to the fields of high-voltage electric appliances, ship manufacturing, new energy equipment and the like, and has the potential of replacing traditional products.

Description

Technical Field

[0001] The present invention belongs to the technical field of rolling composite, and particularly relates to a production method of a T2+Q355B copper-steel rolled composite plate. Background Art

[0002] Copper has good ductility, electrical and thermal conductivity, and corrosion resistance, and is widely used in the fields of electricity, aviation, aerospace, automobiles, etc. In recent years, with the development of copper resources and the rapid development of electric energy, copper resources have become more precious and the price of copper has soared all the way; while steel has a large reserve, low price, and good mechanical properties. Copper / steel bimetallic composites can save a large amount of precious metal copper, reduce costs, have good economic benefits, and have excellent bonding strength, mechanical properties, and electrical conductivity, solving the contradiction that the good electrical conductivity and high strength of copper alloys cannot coexist. The preparation methods of composite plates are usually explosive composite method and rolling composite method. The explosive composite method has low efficiency, high cost, large environmental pollution, poor surface quality, low interface bonding rate, and unstable bonding strength. The rolling composite method is divided into cold rolling composite method and hot rolling composite method. The cold rolling composite method requires large plastic deformation, poor metallurgical bonding effect, low interface bonding strength, and limited size of the composite plate; while the hot rolling composite method can obtain copper-steel composite plates with excellent bonding strength, surface quality, and complete specifications by utilizing the equipment and technical advantages of wide and thick plate production lines.

[0003] This product can be widely used in the fields of high-voltage electrical appliances, shipbuilding, and new energy equipment, and has the potential to replace traditional products. Its industrial application will strongly promote the upgrading and development of strategic industries such as power equipment and ocean engineering. Summary of the Invention

[0004] The purpose of the present invention is to provide a production method of a T2+Q355B copper-steel rolled composite plate. This method produces a copper-steel composite plate with a substrate thickness range of 5 - 40 mm, a cladding thickness range of 1 - 20 mm, and a width ≤ 3600 mm through composite plate blanking + welding blank + rolling + finishing.

[0005] The present invention aims to provide a production method of a T2+Q355B copper-steel rolled composite plate, and obtain a T2+Q355B copper-steel rolled composite plate with excellent bonding strength, mechanical properties, and electrical conductivity, wherein the substrate thickness range is 5 - 40 mm, the cladding thickness range is 1 - 20 mm, the width ≤ 3600 mm, the yield strength ≥ 250 Mpa, the tensile strength is 350 - 600 Mpa, the shear strength ≥ 120 MPa, the electrical conductivity of the cladding T2 copper IACS ≥ 85%, and the intergranular corrosion crack rate is 0.

[0006] The technical solution of the present invention: A production method of T2+Q355B copper-steel rolled composite plate, with the substrate thickness ranging from 5 to 40 mm, the cladding thickness ranging from 1 to 20 mm, the width ≤ 3600 mm, the yield strength ≥ 250 Mpa, the tensile strength 350 - 600 Mpa, the shear strength ≥ 120 MPa, the conductivity of the composite material T2 copper IACS ≥ 85%, and the intergranular corrosion crack rate being 0; the chemical composition by weight percentage of the substrate Q355B is C = 0.15% - 0.18%, Si = 0.20% - 0.40%, Mn = 1.5% - 1.6%, P ≤ 0.018%, Alt = 0.025% - 0.050%, S ≤ 0.003%, Nb = 0.015% - 0.025%, Ti = 0.010% - 0.020%, and the balance is Fe and unavoidable impurities; the chemical composition by mass percentage of the composite material T2 copper is Cu ≥ 99.9%, and the balance is unavoidable impurities; it includes the following process steps: (1) Billet assembling: The symmetrical billet assembling method is ABBA, the substrate A is Q355B, the composite material B is T2, prepare two pieces of Q355B, two pieces of T2, and one piece of sealing plate Q235B, and complete the processes of blanking, surface treatment, applying isolation agent, bevelling, assembling, welding and encapsulating the billet, and vacuum pumping; (2) Heating: After the composite billet is vacuum pumped, it is charged into the furnace for heating within 72 hours. The heating temperature is 840 - 860 °C, the heating rate ≤ 3 min / mm, the total time in the furnace ≥ the thickness of the composite billet × 1.5 min / mm, and the discharging temperature is 840 - 860 °C; (3) Rolling: Single-stage rolling, the starting rolling temperature is 810 - 840 °C, the finishing rolling temperature is 780 - 820 °C, the reduction amount ≤ 30 mm, following the principle that the reduction rate of each pass first increases and then decreases, and the reduction rate of the last three passes ≤ 15%, and the rolling speed ≤ 3%; (4) Stack cooling: After the steel plate is taken off the production line, it is stack cooled. The starting stack cooling temperature is 200 - 300 °C, and the stack cooling time ≥ 48 h; (5) Finishing: The composite plate is separated into sheets, cleaned, straightened, polished, sized, and packed and shipped.

[0007] Furthermore, in the step (1), for blanking, there are two pieces of Q355B substrate blanks, two pieces of copper blanks, and one piece of sealing plate. The compression ratio of the composite billet / product is 5.0 - 8.0; the width of the Q355B substrate blank = the T2 copper blank + 200 mm, and the length of the Q355B substrate blank = the T2 copper blank + 200 mm; Q235B is used as the sealing plate and is used for filling around the composite material copper blank, with the same thickness as the T2 copper blank.

[0008] Furthermore, in the billet assembling of step (1), for surface treatment: The substrate Q355B is ground with a grinding wheel to ensure no scale, showing metallic luster, and no oil stains, debris, imprints, etc.; both sides of the copper blank T2 are polished with a polishing machine to show metallic luster, and no oil stains, debris, imprints, etc.

[0009] Further, in step (1) of blank assembly, beveling is carried out: for two ground base materials, welding bevels are opened around the perimeter, the bevel depth is 30 mm, and the bevel angle is 30°.

[0010] Further, in step (1) of blank assembly, applying a release agent: brush a release agent on the contact surface of copper blank T2, the material is magnesium oxide, the thickness is 0.08 - 0.2 mm, evenly coat the entire copper plate and then bake it, the baking temperature is 450 - 500 °C, and the time is 30 - 40 min.

[0011] Further, in step (1) of blank assembly, assembling: stack in the thickness direction in the order of Q355B + T2 release agent + release agent T2 + Q355B; the composite copper blank T2 is located at the center of the base material blank. After the blank assembly machine is hydraulically pressed, ensure that there is no gap between the contact surface of the sealing plate and the base material blank, and fix it by manual spot welding.

[0012] Further, in step (1) of blank assembly, welding and encapsulating the blank: fully weld around the composite blank, and the weld depth is 25 - 40 mm.

[0013] Further, in step (1) of blank assembly, evacuating: mechanically drill holes and evacuate at the weld position, the vacuum degree ≤ -0.1 MP, maintain the state for more than 60 minutes and then seal the vacuum connection pipe.

[0014] Further, in step (4) of stacking and cooling: put it into a heat preservation pit for slow cooling.

[0015] The present invention relates to a technology of vacuum rolling composite + symmetric blank assembly + low-speed deformation. Utilizing the existing equipment and technical advantages of a wide and heavy plate mill, the process is simple, the process flow is short, and the cost is low, obtaining a T2 + Q355B copper-steel rolled composite plate with excellent bonding strength, mechanical properties and electrical conductivity. The hot working temperature of copper is 600 - 900 °C, and the elongation can reach 60% - 80%; while the hot working temperature of steel is 850 - 1250 °C, and the elongation is 40% - 60%; the different heating softening temperatures and different ductilities of the two materials result in asynchronous deformation. At the same time, during the heating process, both copper and steel will generate oxides, affecting the composite of the two metals. This method adopts the "vacuum rolling composite + symmetric blank assembly + low-speed deformation technology", taking advantage of the equipment and technical advantages of the wide and heavy plate mill, and well solves this contradiction. Vacuum rolling composite can avoid the generation of oxides at the copper-steel composite interface, which is beneficial to the copper-steel rolling composite; symmetric blank assembly (ABBA) and low-speed deformation technology can ensure the uniform deformation of copper and steel during the rolling process, prevent defects such as microcracks from occurring at the copper-steel interface, and are beneficial to the copper-steel rolling composite.

[0016] The present invention has the following beneficial effects: The T2+Q355B copper-steel rolled composite plate produced by this method has a substrate thickness range of 5 to 40 mm, a clad layer thickness range of 1 to 20 mm, a width ≤ 3600 mm, a yield strength ≥ 250 Mpa, a tensile strength of 350 to 600 Mpa, a shear strength ≥ 120 MPa, the conductivity of the clad layer T2 copper IACS ≥ 85%, and the intergranular corrosion crack rate is 0. The copper-steel composite plate not only maintains the excellent mechanical properties of steel but also has the excellent conductivity of copper, and can be widely used in the fields of high-voltage electricity and new energy equipment. Description of the Drawings

[0017] Figure 1 It is a typical metallographic structure photograph of the T2+Q355B copper-steel rolled composite plate in Example 1. Detailed Embodiment

[0018] The present invention will be further described below through examples. Example 1: Production of a 10+6 mm thick T2+Q355B copper-steel rolled composite plate The chemical compositions of copper T2 and steel Q355B are shown in Table 1, with the balance being Fe and unavoidable impurity elements. The finished product has a width of 1700 mm and a length of 9000 mm. The key production process steps include: (1) Stacking the composite plate blanks: Cutting: Two rectangular Q355B substrate blanks with dimensions: 50*2000*2200 mm; two rectangular T2 copper blanks: 30*1800*2000; a sealing plate Q235B with a thickness of 30 mm is laid around the clad material T2 copper blank for filling.

[0019] Surface treatment of the substrate Q355B and the clad material T2 copper blank: The substrate Q355B is polished with a grinding wheel to ensure no scale, the substrate shows a metallic luster, and there are no oil stains, sundries, imprints, etc.; the copper blank T2 is polished with a polishing machine to show a metallic luster, and there are no oil stains, sundries, imprints, etc.

[0020] Beveling: Welding bevels are opened on the four sides of the substrate, with a bevel depth of 30 mm and a bevel angle of 30°.

[0021] Applying the release agent: The contact surface of the copper blank T2 is brushed with a release agent made of magnesium oxide with a thickness of 0.15 mm. After evenly coating the entire plate surface, it is baked at a baking temperature of 460 °C for 35 minutes.

[0022] Stacking the blanks: Stack them symmetrically (ABBA), and stack them in the thickness direction in the order of Q355B+T2 (release agent)+(release agent)T2+Q355B. The clad material copper blank T2 is located at the center of the substrate blank. After being pressed by the blank stacking machine, ensure that there is no gap between the contact surface of the sealing plate and the substrate blank, and fix it by manual spot welding.

[0023] Welded blank encapsulation: The composite blank is fully welded around the perimeter, with a weld depth of 30 mm. Submerged arc welding is used, with a current of 380 A, a voltage of 36 V, and a speed of 20 cm / min.

[0024] Vacuum pumping: Mechanically drill holes and pump vacuum at the weld position. The vacuum degree ≤ -0.1 MP, and the state is maintained for 80 minutes. After confirming the stable negative pressure of the composite blank, seal the vacuum connection pipe.

[0025] (2) Heating: The composite blank is loaded into the furnace for heating within 72 hours after vacuum pumping. Control the heating temperature at 855 °C, the heating rate at 1.5 min / mm, the total time in the furnace at 280 min, and the furnace outlet temperature at 850 °C.

[0026] (3) Rolling: Single-stage rolling is adopted. The starting rolling temperature is 830 °C, the final rolling temperature is 810 °C, and the reduction per pass in the first three passes is 28 mm. Follow the principle that the reduction rate per pass first increases and then decreases. The reduction rates in the last three passes are 8%, 6%, and 4% respectively, and the rolling speed is 1.8 - 2.8 m / s.

[0027] (4) Pile cooling: After the steel plate is taken off the production line, it is piled for cooling. The starting temperature of pile cooling is 260 °C. It is lifted into the heat preservation pit, and at least 6 steel plates with the same temperature are stacked in the heat preservation pit. The pile cooling time is 50 h.

[0028] (5) Finishing: The composite plate is separated into sheets, cleaned, straightened, polished, cut to length, and packed for shipment.

[0029] Example 2: Production of T2 + Q355B copper-steel rolled composite plate with a thickness of 30 + 10 mm The chemical compositions of copper T2 and steel Q355B are shown in Table 2, with the balance being Fe and unavoidable impurity elements. The finished product width is 1700 mm and the length is 9000 mm: The key production process steps include: (1) Composite plate blank assembly: Blanking: Two rectangular Q355B base material blanks, dimensions: 150 * 2000 * 2200 mm; two rectangular T2 copper blanks: 50 * 1800 * 2000; Sealing plate Q235B, with a thickness of 50 mm, is laid around the T2 copper blank of the composite material for filling.

[0030] Surface treatment of the base material Q355B and the composite material T2 copper blank: The base material Q355B is polished with a grinding wheel to ensure no scale, the base material shows metallic luster, and there is no oil stain, debris, or imprint; The copper blank T2 is polished with a polishing machine to show metallic luster, and there is no oil stain, debris, or imprint.

[0031] Beveling: Welding bevels are opened on the four sides of the base material, with a bevel depth of 30 mm and a bevel angle of 30 °C.

[0032] Apply release agent: Brush the release agent on the contact surface of copper billet T2. The material is magnesium oxide with a thickness of 0.13 mm. After evenly coating the entire board surface, bake it at a baking temperature of 465 °C for 36 minutes.

[0033] Blank assembly: Assemble symmetrically (ABBA), stack in the thickness direction in the order of Q355B + T2 (release agent) + (release agent) T2 + Q355B. The composite copper billet T2 is located at the center of the base material billet. After being pressed by the blank assembly machine, ensure that there is no gap between the sealing plate and the contact surface of the base material billet, and fix it by manual spot welding.

[0034] Welded blank encapsulation: Weld the periphery of the composite blank full, the weld depth is 35 mm, submerged arc welding, current 385 A, voltage 36 V, speed 20 cm / min.

[0035] Vacuum pumping: Mechanically drill holes and pump vacuum at the weld position. The vacuum degree ≤ -0.1 MP, maintain the state for 80 minutes. After confirming the stability of the negative pressure of the composite blank, then seal the vacuum connection pipe.

[0036] (2) Heating: Furnace heating is carried out within 72 hours after the composite blank is vacuum pumped. Control the heating temperature at 858 °C, the heating rate is 1.5 min / mm, the total time in the furnace is 800 min, and the furnace outlet temperature is 852 °C.

[0037] (3) Rolling: Adopt single-stage rolling, the starting rolling temperature is 835 °C, the final rolling temperature is 815 °C, the reduction in the first three passes is 27 mm; follow the principle that the reduction rate of each pass first increases and then decreases. The reduction rates of the last three passes are 7%, 5%, and 3% respectively, and the rolling speed is 1.9 - 2.5 m / s.

[0038] (4) Stack cooling: Stack cooling is carried out after the steel plate is taken off the production line. The starting temperature of stack cooling is 285 °C, lift it into the heat preservation pit. At least 6 steel plates with the same temperature are stacked in the heat preservation pit, and the stack cooling time is 60 h.

[0039] (5) Finishing: Cut the composite plate into sheets, clean, straighten, polish, cut to length, and pack and ship.

[0040] Table 1 Chemical composition of base material Q355B and composite material T2 copper in Example 1 (weight, %) 。

[0041] Table 2 Chemical composition of base material Q355B and composite material T2 copper in Example 2 (weight, %) 。

[0042] Table 3 Properties of the composite plate in Example 1 。

[0043] Table 4 Properties of the composite plate in Example 2 。

Claims

1. A production method of a T2+Q355B copper-steel rolled composite plate, characterized in that: The substrate thickness ranges from 5 to 40 mm, the cladding layer thickness ranges from 1 to 20 mm, the width ≤ 3600 mm, the yield strength ≥ 250 Mpa, the tensile strength is 350 - 600 Mpa, the shear strength ≥ 120 MPa, the electrical conductivity of the clad material T2 copper in IACS ≥ 85%, and the intergranular corrosion crack rate is 0; the chemical composition of the substrate Q355B in weight percentage is C = 0.15% - 0.18%, Si = 0.20% - 0.40%, Mn = 1.5% - 1.6%, P ≤ 0.018%, S ≤ 0.003%, Alt = 0.025% - 0.050%, Nb = 0.015% - 0.025%, Ti = 0.010% - 0.020%, and the balance is Fe and unavoidable impurities; the chemical composition of the clad material T2 copper in mass percentage is Cu ≥ 99.9%, and the balance is unavoidable impurities; It includes the following technological steps: (1) Blank assembling: The symmetrical blank assembling method is ABBA, the substrate A is Q355B, the clad material B is T2. Prepare two pieces of Q355B, two pieces of T2, and one piece of sealing plate Q235B. Complete the processes of blanking, surface treatment, applying release agent, beveling, assembling, welding blank encapsulation, and vacuum pumping; (2) Heating: After the composite blank is vacuum pumped, it is charged into the furnace for heating within 72 hours. The heating temperature is 840 - 860 °C, the heating rate ≤ 3 min / mm, the total time in the furnace ≥ the thickness of the composite blank × 1.5 min / mm, and the furnace outlet temperature is 840 - 860 °C; (3) Rolling: Single-stage rolling. The starting rolling temperature is 810 - 840 °C, the final rolling temperature is 780 - 820 °C, the reduction ≤ 30 mm. Follow the principle that the reduction rate per pass first increases and then decreases, and the reduction rate of the last three passes ≤ 15%, and the rolling speed ≤ 3%; (4) Pile cooling: After the steel plate is taken off the production line, it is subjected to pile cooling. The starting pile cooling temperature is 200 - 300 °C, and the pile cooling time ≥ 48 h; (5) Finishing: The composite plate is cut into sheets, cleaned, straightened, polished, sized, and packed for shipment.

2. The production method of a T2 + Q355B copper-steel rolled composite plate according to claim 1, characterized in that In the step (1) blank assembling: There are two blanks of Q355B substrate, two copper blanks, and one sealing plate. The compression ratio of the composite blank / finished product is 5.0 - 8.0; The width of the Q355B substrate blank = the T2 copper blank + 200 mm, and the length of the Q355B substrate blank = the T2 copper blank + 200 mm; Q235B is used as the sealing plate and is used for filling around the copper clad blank. Its thickness is the same as that of the T2 copper blank.

3. The production method of a T2+Q355B copper-steel rolled composite plate according to claim 1, characterized in that In the surface treatment in the step (1): The substrate Q355B is ground with a grinding wheel to ensure no mill scale, showing metallic luster, and no oil stains, debris, or imprints; Both sides of the copper blank T2 are polished with a polishing machine to show metallic luster, and no oil stains, debris, or imprints.

4. The production method of a T2+Q355B copper-steel rolled composite plate according to claim 1, characterized in that: In the beveling in the step (1) blank assembling: For the two ground substrates, welding bevels are opened around, the bevel depth is 30 mm, and the bevel angle is 30 °C.

5. The production method of a T2+Q355B copper-steel rolled composite plate according to claim 1, characterized in that: In the applying release agent in the step (1) blank assembling: The contact surface of the copper blank T2 is brushed with a release agent. The material is magnesium oxide, the thickness is 0.08 - 0.2 mm. After evenly coating the entire copper plate, it is baked. The baking temperature is 450 - 500 °C, and the time is 30 - 40 min.

6. The production method of a T2+Q355B copper-steel rolled composite plate according to claim 1, characterized in that: In the blanking and assembling step (1): Stack in the thickness direction in the order of Q355B + T2 release agent + release agent T2 + Q355B; the composite copper blank T2 is located at the center of the base material blank. After being hydraulically pressed by the blanking machine, ensure that there is no gap between the sealing plate and the contact surface of the base material blank, and fix it by manual spot welding.

7. The production method of a T2+Q355B copper-steel rolled composite plate according to claim 1, characterized in that: In the welding and blank encapsulation step (1): Full welding is performed around the composite blank, and the weld depth is 25 - 40 mm.

8. The production method of a T2+Q355B copper-steel rolled composite plate according to claim 1, characterized in that: In the vacuum pumping step (1): Mechanically drill holes and pump vacuum at the weld position, the vacuum degree ≤ -0.1 MP, and keep the state for more than 60 minutes before closing the vacuum connection pipe.

9. The production method of a T2 + Q355B copper-steel rolled composite plate according to claim 1, characterized in that: In the step (4) of stacking and cooling: Slowly cool in a heat preservation pit.

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