Production method of copper-steel rolled composite plate for deep sea environment

Abstract

A production method of copper-steel rolled composite plate for deep sea environment, the copper is oxygen-free copper TU2, Cu >= 99.95%; the process steps include raw material treatment, assembly, composite blank rolling, heat treatment, finishing. The copper-steel composite plate produced by the application has yield strength >= 355 MPa, tensile strength >= 470 MPa, elongation >= 22%, Charpy V-type impact energy at -60 DEG C >= 120 J, shear strength >= 200 MPa, and the composite plate has good plate shape, high bonding rate and small residual stress, and is suitable for use in deep sea extremely cold and corrosive environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rolling composite, and relates to a production method of a copper-steel rolling composite plate for deep sea environment. BACKGROUND

[0002] Metallic copper has excellent biological corrosion resistance, especially in inhibiting the attachment and growth of marine organisms. When copper contacts seawater, a dense layer of copper oxide is formed, which can effectively isolate external media; at the same time, the copper ions released by corrosion have a natural inhibitory effect on most marine organisms such as bacteria and fungi, effectively reducing biological attachment and corrosion, so that copper has a wide application in marine engineering, ship equipment and the like. However, copper is a relatively soft metal, and the yield strength of pure copper is only 60-100 MPa, which limits its use as a structural material. Copper-steel bimetallic composite material can simultaneously have the characteristics of copper and steel, and the mechanical properties are significantly improved while the corrosion resistance is obtained. However, the existing technology mainly focuses on the shear strength of the bonding surface of the copper-steel composite plate, and few involves improving the strength and toughness of the composite plate. SUMMARY

[0003] The purpose of the application is to provide a production method of a copper-steel rolling composite plate for deep sea environment, which effectively improves the strength and toughness of the copper-steel composite plate through blank control, controlled rolling and controlled cooling, and heat treatment and the like processes.

[0004] The technical scheme of the application is as follows:

[0005] A production method of a copper-steel rolling composite plate for deep sea environment, the process flow includes raw material treatment, blank assembly, composite blank rolling, heat treatment, and finishing; the copper is oxygen-free copper, Cu≥99.95%; the chemical composition of the steel has a mass percentage of C≤0.10%, Si≤0.50%, Mn≤1.60%, P≤0.012%, S≤0.003%, Al=0.02%-0.05%, Nb=0.01%-0.05%, Ni=0.80%-2.0%, O≤0.002%, N≤0.008%, H≤0.00015%, and the balance is Fe and inevitable impurities; the process steps include:

[0006] (1) Raw material treatment: copper blank is obtained by cold rolling, and the cold rolling reduction rate is not less than 50%; steel blank is produced by hot rolling, and the rolling reduction rate is controlled to be ≥40% in the temperature range of 860-900℃, and the rolling reduction rate is controlled to be ≥30% below the temperature, and the rolled product is air cooled to room temperature; wherein, A r3 Tc is the critical temperature at which the austenite starts to transform into proeutectoid ferrite in the cooling process; A r3 Tc is the critical temperature at which the austenite starts to transform into proeutectoid ferrite in the cooling process;

[0007] (2) Assembling: straightening and polishing the copper and steel blanks; assembling the blanks symmetrically with steel / copper / separator / copper / steel, and controlling the rolling direction of the copper blank to be consistent with that of the steel blank, while making the steel blank completely cover the copper blank, with at least 50 mm of excess length of the industrial pure iron sealing strip inserted into the gap, and making the gap between the sealing strip and the copper blank be 1-10 mm, and then welding the sealing strip and the steel blank and vacuumizing;

[0008] (3) Rolling of the composite blank: heating the composite blank to 860-900℃ and keeping the temperature for more than 60 min; setting the vertical direction of the rolling direction of the copper blank and the steel blank as the longitudinal rolling direction of the current rolling, and using longitudinal rolling in each pass, with the total compression ratio being ≥5; controlling the finish rolling temperature to be 20-60℃ higher than the temperature above; A r3 cooling at a cooling rate of 5-20℃ / s to 450-550℃, and then air cooling to room temperature;

[0009] (4) Heat treatment: heating the rolled composite plate to 450-550℃ and keeping the temperature for 1-2 h;

[0010] (5) Finishing: separating the copper-steel composite plate.

[0011] Preferably, the chemical composition of the steel contains, by mass, C=0.05%-0.08%, Si≤0.20%, Mn=0.90-1.60%, P≤0.012%, S≤0.003%, Al=0.03%-0.04%, Nb=0.015%-0.025%, Ni=0.80%-2.0%, O≤0.0015%, N=0.003%-0.005%, H≤0.00012%, and the balance being Fe and unavoidable impurities. Further, the chemical composition of the steel can further contain one or more of Cr≤0.30%, Mo≤0.20%, and V≤0.05%.

[0012] Further, in step (1) raw material treatment, the steel blank is heated and rolled to obtain a ferrite+pearlite structure with a grain size of ≥9 levels.

[0013] Further, in step (2) assembling, the welding is performed by submerged arc welding, and the process includes opening a single V-shaped groove with a depth of 30-50 mm around the steel blank, using industrial pure iron welding material, and controlling the heat input to be 3.0-4.5 kJ / cm;

[0014] Further, in step (2) assembling, the industrial pure iron has Fe≥99.9% and a tensile elongation of ≥30%.

[0015] Further, step (2) group blank: the vacuum, in parallel to the composite blank longitudinal rolling direction of the edge sealing bar center position mechanical drilling, depth through the sealing bar width, then vacuum, control vacuum degree <0.1MPa, keep 60min above, after welding closed air hole.

[0016] The innovation point of the present application creates the creative principle:

[0017] 1) The copper blank of the present application adopts cold rolling, which makes the crystal grains elongate along the rolling direction, forming deformation texture towards the rolling direction. During the subsequent composite blank heating and rolling, on the one hand, it is beneficial to slow down the grain growth rate, thereby refining the original grains, and on the other hand, by taking the vertical direction of the original rolling direction as the main direction during hot rolling, the copper layer of the composite plate after rolling is uniform and fine in both horizontal and vertical directions.

[0018] 2) The steel blank of the present application is Al killed steel and Al+Nb intrinsic fine-grained steel. In order to fully play the role of Al and Nb, the steel blank is deformed by large reduction during hot rolling at a temperature interval of 860~900℃, which has a high nucleation rate, thereby reducing the size of precipitated particles and making them disperse. In addition, the heating temperature of the composite blank is controlled to be in this temperature interval, so that the fine and dispersed precipitates can be effectively retained during austenitizing heating. Furthermore, in the production process, in order to improve the uniformity of the horizontal and vertical microstructures of the final composite plate, the steel blank is controlled to have a certain reduction in the two-phase region, forming a band-shaped structure towards the rolling direction, and then the composite blank is rolled mainly in the direction perpendicular to the band-shaped structure.

[0019] 3) The sealing strip of the present application adopts industrial pure iron, and is welded and sealed with steel blank using industrial pure iron welding material. The ductility of industrial pure iron and oxygen-free copper is not much different, and they have good deformation coordination during the high compression ratio rolling deformation adopted in the present application, avoiding the warping of the inner layer oxygen-free copper of the composite blank due to limited rolling extension, resulting in plate shape defects such as buckling head and wave.

[0020] 4) The composite plate of the present application adopts low-carbon high-nickel composition design for the steel layer, so that the steel matrix has good low-temperature toughness. At the same time, low-temperature heating and low-temperature large reduction rolling, as well as rapid cooling and heat treatment process are adopted, so that the steel layer mainly has acicular ferrite structure, which has good strength and toughness matching. In addition, the high nickel content of the steel layer easily diffuses into the copper-steel bonding layer and the copper layer during heat treatment, forming fine Ni-Cu phase, which improves the strength of the copper layer and the shear strength of the copper-steel bonding surface. In addition, the low-carbon, low-hydrogen and low-oxygen control of the steel layer avoids the excessive entry of hydrogen into the oxygen-free copper during heat treatment, which causes "hydrogen disease" and other hazards.

[0021] The copper-steel composite plate produced by the application has good comprehensive mechanical properties, and the transverse and longitudinal tensile, impact and shear properties can meet the requirements of yield strength ≥355 MPa, tensile strength ≥470 MPa, elongation ≥22%, -60℃ Charpy V-type impact energy ≥120 J and shear strength ≥200 MPa, and the composite plate has good shape, high bonding rate and small residual stress, and is suitable for use in deep sea and extremely cold and corrosive environment. DETAILED DESCRIPTION

[0022] The application will be further described by examples.

[0023] Example 1

[0024] A production method of a copper-steel rolling composite plate for deep sea environment, the copper is oxygen-free copper TU2, Cu ≥ 99.95%; the chemical composition of the steel is mass percentage of C = 0.06%, Si = 0.12%, Mn = 1.15%, P = 0.01%, S = 0.002%, Al = 0.035%, Nb = 0.02%, Ni = 1.05%, O = 0.0012%, N = 0.0036%, H ≤ 0.00012%, and the balance is Fe and inevitable impurities; the process steps include:

[0025] (1) Raw material treatment: the copper blank is obtained by cold rolling, and the cold rolling reduction is 65%; the steel blank is produced by hot rolling, the rolling reduction is 52.6% in the temperature range of 860-900℃, and the temperature is controlled A r3 below 860℃ after rolling, and the rolling reduction is 32.8%, and the ferrite + pearlite structure is obtained by air cooling to room temperature after rolling, and the grain size is 11 grade; wherein, the critical temperature of austenite starting to transform into proeutectoid ferrite in the cooling process A r3 is about 755℃;

[0026] (2) Group blank: the copper blank and the steel blank are subjected to straightening, polishing and other treatments; then the steel / copper / separator / copper / steel symmetric group blank is adopted, and the rolling direction of the copper blank and the steel blank is kept consistent, at the same time, the steel blank completely covers the copper blank, the four sides are at least 50mm excess amount of YT2 industrial pure iron sealing strip is inserted, and the gap between the sealing strip and the copper blank is 1-10mm, then the sealing strip and the steel blank are welded and vacuumized; the industrial pure iron YT2, Fe ≥ 99.9%, the tensile elongation is 45%; the welding adopts submerged arc welding, the process includes opening a single V-type groove with a depth of 35mm around the steel blank, using industrial pure iron welding material, and controlling the heat input of 3.0-4.5kJ / cm; the vacuumization is mechanical drilling at the center position of the edge sealing strip parallel to the longitudinal rolling direction of the composite blank, the depth penetrates the width of the sealing strip, then vacuumization is carried out, the vacuum degree is controlled to be less than 0.1MPa, the holding time is 80min, and then the air hole is welded and closed.

[0027] (3) Composite blank rolling: the composite blank is heated to 880℃ and kept for 80 min; the vertical direction of the copper blank and the steel blank is set as the longitudinal rolling direction of the current rolling, and longitudinal rolling is adopted in each pass, and the total compression ratio is 5; the finish rolling temperature is controlled to be 800℃; after rolling, it is cooled to 500-540℃ at a cooling speed of about 15℃ / s, and then air-cooled to room temperature;

[0028] (4) Heat treatment: the rolled composite plate is heated to 500±10℃ and kept for 1.2h;

[0029] (5) Finishing: the copper-steel composite plate is obtained by separating.

[0030] The mechanical properties of the copper-steel composite plate are detected by sampling. The transverse direction: yield strength is 378MPa, tensile strength is 552MPa, elongation is 34%, -60℃ Charpy V-type impact energy is 186J, and shear strength is 205MPa; the longitudinal direction: yield strength is 382MPa, tensile strength is 555MPa, elongation is 34%, -60℃ Charpy V-type impact energy is 190J, and shear strength is 207MPa.

[0031] Example 2

[0032] A production method of a copper-steel rolled composite plate for deep-sea environment, the copper is oxygen-free copper TU2, Cu≥99.95%; the chemical composition of the steel is mass percentage of C=0.07%, Si=0.11%, Mn=1.38%, P=0.008%, S=0.002%, Al=0.036%, Nb=0.021%, Ni=1.62%, O=0.0011%, N=0.0041%, H≤0.00012%, and the balance is Fe and inevitable impurities; the process steps include:

[0033] (1) Raw material treatment: the copper blank is prepared by cold rolling, and the cold rolling reduction rate is 72%; the steel blank is produced by hot rolling, and the rolling reduction rate is 43.6% in the temperature range of 860-900℃, and the rolling reduction rate is controlled to be 38.5% below the temperature of 700℃, and the ferrite+pearlite structure is obtained by air cooling to room temperature after rolling, and the grain size is 10 levels; wherein, the critical temperature of austenite starting to transform into proeutectoid ferrite in the cooling process is about 710℃; A r3 A r3

[0034] ​​(2) Group blank: straighten, polish and other treatments are carried out on copper blank and steel blank; then the steel / copper / separator / copper / steel is symmetrically grouped, and the rolling direction of the copper blank and the steel blank is kept consistent, at the same time, the steel blank completely covers the copper blank, the four sides are at least 50mm excess inserted into the YT2 industrial pure iron sealing strip, and the gap between the sealing strip and the copper blank is 1-10mm, then the sealing strip and the steel blank are welded and vacuumized; the industrial pure iron YT2, Fe≥99.9%, the tensile elongation is 45%; the welding, using submerged arc welding, the process includes opening a single V-shaped groove with a depth of 45mm around the steel blank, using industrial pure iron welding material, and controlling the heat input of 3.0-4.5kJ / cm; the vacuumization, mechanical drilling at the center position of the sealing strip on the side parallel to the longitudinal rolling direction of the composite blank, the depth penetrates the width of the sealing strip, then vacuumizing, controlling the vacuum degree <0.1MPa, and keeping the time for 75min, then welding to close the air hole;

[0035] (3) Composite blank rolling: the composite blank is heated to 890℃, and the temperature is kept for 120min; the vertical direction of the original rolling direction of the copper blank and the steel blank is set as the longitudinal rolling direction of the current rolling, and the longitudinal rolling is used in each pass, and the total compression ratio is 6; the finish rolling temperature is controlled to be 750℃; after rolling, the cooling speed is about 8℃ / s, and the temperature is cooled to 460-500℃, and then air cooling is carried out to room temperature;

[0036] (4) Heat treatment: the rolled composite plate is heated to 500±10℃, and the temperature is kept for 1.8h;

[0037] (5) Finishing: the copper-steel composite plate is obtained by separating.

[0038] The mechanical properties of the copper-steel composite plate are detected by sampling. The transverse direction: the yield strength is 426MPa, the tensile strength is 574MPa, the elongation is 33%, the Charpy V-type impact energy at-60℃ is 225J, and the shear strength is 216MPa; the longitudinal direction: the yield strength is 433MPa, the tensile strength is 579MPa, the elongation is 32%, the Charpy V-type impact energy at-60℃ is 211J, and the shear strength is 212MPa.

[0039] Example 3

[0040] A production method of a copper-steel rolled composite plate for deep sea environment, the copper is oxygen-free copper TU2, Cu≥99.95%; the chemical composition of the steel is mass percentage C=0.07%, Si=0.25%, Mn=0.85%, P=0.007%, S=0.002%, Al=0.042%, Nb=0.033%, Ni=1.85%, O=0.0016%, N=0.0052%, H≤0.00015%, Cr=0.21%, Mo=0.15%, V=0.025%, and the balance is Fe and inevitable impurities; the process steps include:

[0041] (1) Raw material processing: the copper blank is prepared by cold rolling with a cold rolling reduction of 56%; the steel blank is prepared by hot rolling with a rolling reduction of 47.8% in the temperature range of 860-900 ℃, and the rolling reduction in the temperature range of 800-850 ℃ is controlled to be 35.1%, and the blank is air-cooled to room temperature after rolling to obtain a ferrite+pearlite structure with a grain size of 10 levels; wherein, the critical temperature at which the austenite starts to transform into proeutectoid ferrite in the cooling process is about 730 ℃; A r3 A r3

[0042] (2) Grouping blank: the copper blank and the steel blank are subjected to straightening, polishing and other treatments; then the steel / copper / separator / copper / steel is symmetrically grouped, and the rolling direction of the copper blank and the steel blank is kept consistent, at the same time, the steel blank completely covers the copper blank, the four sides are at least 50 mm excess inserted into the YT2 industrial pure iron sealing strip, and there is a gap of 1-10 mm between the sealing strip and the copper blank, then the sealing strip and the steel blank are welded and vacuumized; the industrial pure iron YT2 has Fe≥99.9% and a tensile elongation of 45%; the welding adopts submerged arc welding, the process includes opening a single V-shaped groove with a depth of 40 mm around the steel blank, using industrial pure iron welding material, and controlling the heat input to be 3.0-4.5 kJ / cm; the vacuumization is mechanical drilling at the center position of the sealing strip on the side parallel to the longitudinal rolling direction of the composite blank, the depth penetrates the width of the sealing strip, then vacuumizing, controlling the vacuum degree to be less than 0.1 MPa, keeping for 65 min, and then welding to close the air hole;

[0043] (3) Composite blank rolling: the composite blank is heated to 870 ℃ and kept for 100 min; the vertical direction of the original rolling direction of the copper blank and the steel blank is set as the longitudinal rolling direction of the current rolling, and each pass adopts longitudinal rolling with a total compression ratio of 8; the finish rolling temperature is controlled to be 770 ℃; after rolling, the cooling speed is about 10 ℃ / s to cool to 480-520 ℃, and then air-cooled to room temperature;

[0044] (4) Heat treatment: the rolled composite plate is heated to 500±10 ℃ and kept for 1.5 h;

[0045] (5) Finishing: the copper-steel composite plate is obtained by separating.

[0046] The mechanical properties of the copper-steel composite plate are detected by sampling. The transverse direction: yield strength is 541 MPa, tensile strength is 659 MPa, elongation is 23%, -60 ℃ Charpy V-type impact energy is 126 J, and shear strength is 221 MPa; the longitudinal direction: yield strength is 563 MPa, tensile strength is 671 MPa, elongation is 22%, -60 ℃ Charpy V-type impact energy is 135 J, and shear strength is 219 MPa.​​

Claims

1. A method for producing a copper-steel rolled clad plate for a deep-sea environment, characterized by: The copper is oxygen-free copper TU2, Cu≥99.95%; the chemical composition of the steel is as follows: C≤0.10%, Si≤0.50%, Mn≤1.60%, P≤0.012%, S≤0.003%, Al=0.02%-0.05%, Nb=0.01%-0.05%, Ni=0.80%-2.0%, O≤0.002%, N≤0.008%, H≤0.00015%, and the balance is Fe and inevitable impurities; the process steps include: (1) Raw material processing: the copper blank is prepared by cold rolling, and the cold rolling reduction is not less than 50%; the steel blank is produced by hot rolling, and the rolling reduction is controlled to be greater than or equal to 40% in the temperature range of 860-900 ℃, the rolling reduction is controlled to be greater than or equal to 30% below the temperature, and air cooling is performed to room temperature after rolling; wherein, A r3 Tc is the critical temperature at which the austenite starts to transform into proeutectoid ferrite in the cooling process; A r3 Tc is the critical temperature at which the austenite starts to transform into proeutectoid ferrite in the cooling process; (2) blank assembling: the copper blank and the steel blank are straightened and polished, then the steel / copper / separator / copper / steel is symmetrically assembled, the rolling direction of the copper blank and the steel blank is kept consistent, the steel blank completely covers the copper blank, the four sides are at least 50mm excess to be inserted into the industrial pure iron sealing strip, and the gap between the sealing strip and the copper blank is 1-10mm, then the sealing strip and the steel blank are welded and vacuumized; (3) Compound blank rolling: the compound blank is heated to 860-900 °C, and the temperature is kept for more than 60 min; the vertical direction of the original rolling direction of the copper blank and the steel blank is set as the longitudinal rolling direction of the current rolling, and longitudinal rolling is adopted in each pass, and the total compression ratio is greater than or equal to 5; the finish rolling temperature is controlled to be 20-60 °C higher than the temperature A r3 After rolling, the temperature is cooled to 450-550 °C at a cooling speed of 5-20 °C / s, and then air-cooled to room temperature; (4) heat treatment: the rolled composite plate is heated to 450-550℃ and kept for 1-2h; (5) finishing: the copper-steel composite plate is obtained.

2. The method of claim 1, wherein the copper-steel clad plate for a deep-sea environment is produced by the steps of: The chemical composition of the steel is as follows: C=0.05%-0.08%, Si≤0.20%, Mn=0.90-1.60%, P≤0.012%, S≤0.003%, Al=0.03%-0.04%, Nb=0.015%-0.025%, Ni=0.80%-2.0%, O≤0.0015%, N=0.003%-0.005%, H≤0.00012%, and the balance is Fe and inevitable impurities. ​ 3. The method for producing a copper-steel rolled composite plate for deep-sea environments according to claim 1, characterized in that, The chemical composition of the steel further includes one or more of Cr≤0.30%, Mo≤0.20% and V≤0.05%.

4. The method of claim 1, wherein the copper-steel clad plate is produced by the steps of: preparing a copper plate; preparing a steel plate; and rolling the copper plate and the steel plate together. Step (1) raw material treatment: the steel blank is hot-rolled to obtain a ferrite+pearlite structure with a grain size≥9 levels.

5. The method for producing a copper-steel rolled composite plate for deep-sea environments according to claim 1, characterized in that... Step (2) blank assembling: the welding is performed by submerged arc welding, and the process includes opening a single V-shaped groove with a depth of 30-50mm around the steel blank, using industrial pure iron welding material, and controlling the heat input to be 3.0-4.5kJ / cm.

6. The method of claim 1, wherein the copper-steel clad plate is produced by the steps of: preparing a copper plate; preparing a steel plate; and rolling the copper plate and the steel plate together. Step (2) blank assembling: the industrial pure iron is Fe≥99.9% and the tensile elongation is≥30%.

7. The method for producing a copper-steel rolled composite plate for deep-sea environments according to claim 1, characterized in that... Step (2) blank assembling: the vacuumization is performed by mechanically drilling a hole at the center of the sealing strip parallel to the longitudinal rolling direction of the composite blank, the depth penetrates the width of the sealing strip, then vacuumizing, controlling the vacuum degree to be<0.1MPa, keeping for more than 60min, and then welding to seal the air hole.