Production method of ultralow-temperature CrMo steel rolled composite plate

Abstract

The invention discloses a production method of an ultralow-temperature CrMo steel rolled composite plate. The ultralow-temperature CrMo steel rolled composite plate with the thickness of 10-60 mm and the width of 1500-3800 mm is produced, and base layer steel comprises the following chemical components in percentage by weight: 0.10-0.14% of C, 0.18-0.25% of Si, 0.45-0.55% of Mn, less than or equal to 0.008% of P, less than or equal to 0.003% of S, 0.02-0.04% of Alt, 0.90-1.10% of Cr, 0.50-0.60% of Mo and 0.12-0.16% of Ni; the cladding stainless steel comprises the following chemical components in percentage by weight: less than or equal to 0.08% of C, less than or equal to 1.00% of Si, less than or equal to 1.00% of Mn, less than or equal to 0.035% of P, less than or equal to 0.015% of S, less than or equal to 0.60% of Ni and 11.5- The process route comprises the steps of blank welding compounding, vacuumizing, controlled rolling and quenched-tempered heat treatment. The bonding rate of the produced composite board reaches 100%, the surface quality of a coating is good, the yield strength at the 1 / 2 thickness position under the inspection supply state and the simulated postweld heat treatment state is larger than or equal to 290 MPa, the tensile strength ranges from 450 MPa to 585 MPa, the yield ratio is smaller than or equal to 0.85, the impact energy at the temperature of-34 DEG C is larger than or equal to 200 J, the shear strength is larger than 300 MPa, and the intergranular corrosion rate is 0.

Description

Technical Field

[0001] The present invention belongs to the technical field of stainless steel composite technology, and relates to a production method of ultra-low temperature CrMo steel rolling composite plate. Background Art

[0002] In the petrochemical industry, its equipment usually operates under high-temperature and high-pressure hydrogen-containing working conditions, requiring the materials of the containers to have high resistance to hydrogen embrittlement, hydrogen peeling and hydrogen corrosion; at the same time, it also has high strength, especially comprehensive indexes such as high-temperature strength and low-temperature toughness. To ensure the long-term safe operation of the equipment, the selected materials must meet the above requirements. CrMo pressure vessel steel has become an important material for large pressure vessel equipment due to its good high-temperature strength, resistance to hydrogen corrosion, high-temperature creep resistance and good low-temperature impact toughness. In the traditional production process of petrochemical equipment, it is usually necessary to build a layer of stainless steel material on the inner wall of the equipment to ensure that the equipment is free from hydrogen corrosion, acid corrosion, etc. during operation and improve the service life of the equipment.

[0003] Rolled bimetal composite plate is a new type of energy-saving and environmental protection material. It uses carbon steel or alloy steel as the base layer and stainless steel as the clad layer, and realizes the complete metallurgical bonding between the base layer and the clad layer through the most advanced hot rolling composite technology. Stainless steel composite plate uses carbon steel or alloy steel as the base layer and stainless steel as the clad layer, realizing the high-strength metallurgical bonding of the two materials. The stainless steel composite plate ensures the strength of the material by the base layer, and ensures the physical properties such as corrosion resistance, cleanliness, wear resistance, beauty and long service life by the clad layer.

[0004] Hot-rolled stainless steel composite plate adopts industrialized continuous production, is not affected by the environment, climate and policies, can be produced efficiently and continuously, and realizes large-batch and rapid delivery. Indoor production is adopted, with less emissions and pollution, and is environmentally friendly and harmless. The metallurgical bonding of the rolled composite plate interface is planar, does not change the effective use thickness of the stainless steel, can withstand repeated bending deformation, and the welding heat-affected zone will not crack. The clad material and the base material are integrally composite, the interface bonding rate is 100%, the splicing welds are few, and the quality hidden dangers are reduced. At the same time, through process technologies such as temperature control, rolling control, cooling control and heat treatment, the mechanical properties of the stainless steel composite plate are improved. Summary of the Invention

[0005] The present invention aims to provide a production method of ultra-low temperature CrMo steel rolling composite plate, in which the bonding rate of the produced ultra-low temperature CrMo steel rolling composite plate reaches 100%, and no delamination and cracking occur in the inspection of internal bending, external bending and side bending, and the surface quality of the clad layer is good. When inspecting the composite plate at half thickness, the yield strength at half thickness in the as-supplied state and the simulated post-weld heat treatment state is ≥290 MPa, the tensile strength is 450 - 585 MPa, the yield ratio is ≤0.80, the impact energy at -34 °C is ≥200 J, the shear strength is >300 MPa, and the intergranular corrosion rate is 0.

[0006] Technical solution of the present invention: A production method of ultra-low temperature CrMo steel rolling composite plate, the thickness of the composite plate is 10 - 60 mm, the width is 1500 - 3800 mm, the chemical composition weight percentage of the base steel is C = 0.10 - 0.14, Si = 0.18 - 0.25, Mn = 0.45 - 0.55, P ≤ 0.008, S ≤ 0.003, Alt = 0.02 - 0.04, Cr = 0.90 - 1.10, Mo = 0.50 - 0.60, Ni = 0.12 - 0.16, and the balance is Fe and inevitable impurity elements; the chemical composition weight percentage of the clad stainless steel is C ≤ 0.08, Si ≤ 1.00, Mn ≤ 1.00, P ≤ 0.035, S ≤ 0.015, Ni ≤ 0.60, Cr = 11.5 - 13.5, and the balance is Fe and inevitable impurity elements; the key process steps include: (1) Double-sided symmetric welding composite: Select two sheets of CrMo steel and two sheets of stainless steel slab respectively. Grind one side of the clad material and the base material until the metal color is exposed, stack them in the order of base material + clad material + magnesium oxide isolation agent + clad material + base material, and weld the four sides of the composite blank by gas shielded welding. After welding, evacuate the inside of the composite blank, and the vacuum degree reaches 5×10 -2 Pa or less, and the pressure holding time ≥ 40 min; (2) Heating: The heating temperature is 1160 - 1200 °C, and the total in-furnace time ≥ 500 min; (3) First-stage rolling: The starting rolling temperature ≥ 1050 °C, the steel plate is rolled in full rolling or full cross-rolling mode, the single-pass reduction is more than 40 mm, the biting speed is 1.3 m / s, and the rolling speed is 2.0 m / s; the final rolling temperature ≥ 980 °C, and the intermediate rolling thickness is the target rolling thickness + 40 - 80 mm; (4) Second-stage rolling: The starting rolling temperature is 910 - 940 °C, the final rolling temperature is 780 - 840 °C, and air cooling is carried out after rolling; (5) Heat treatment: The composite plate is subjected to quenching + tempering heat treatment. The quenching temperature is 910 - 940 °C, and the time is 2.0 - 2.5 min / mm; the tempering temperature is 710 - 740 °C, and the tempering time is 3.0 - 3.5 min / mm; The bonding rate of the produced ultra-low temperature CrMo steel rolling composite plate reaches 100%. When inspecting the composite plate at 1 / 2 thickness in the as-supplied state and after simulated post-weld heat treatment, the yield strength at 1 / 2 thickness ≥ 290 MPa, the tensile strength is 450 - 585 MPa, the yield ratio ≤ 0.80, the impact energy at -34 °C ≥ 200 J, the shear strength > 300 MPa, and the intergranular corrosion rate is 0.

[0007] Advantages of the present invention: The production is carried out by the method of symmetric welding composite. Through the processes of blank welding composite + vacuum pumping + controlled rolling + quenching and tempering heat treatment, combined with a suitable composition design, the process is simple, highly operable, does not require processes such as milling and turning of the base plate, has high production efficiency and low manufacturing cost. High-temperature large reduction is adopted in rolling to ensure effective composite of the base layer and the clad layer at the high-temperature stage. At the same time, controlled rolling is carried out for the second-stage rolling to refine the original grains of the base layer. Finally, through the heat treatment of quenching + tempering, the composite plate obtains a suitable microstructure, ensuring the strength and ultra-low temperature impact toughness of the steel plate. Description of the Drawings

[0008] Figure 1 It is the microstructure morphology diagram of the base layer in Example 1.

[0009] Figure 2 It is the macroscopic morphology diagram of intergranular corrosion in Example 1. Detailed Embodiments

[0010] The present invention will be further described below through examples. Example 1

[0011] A production method of an ultra-low temperature CrMo steel rolled composite plate SA387Gr12CL2 + SA240TP410S. The chemical compositions of the base material SA387Gr12CL2 and the clad material SA240 TP410S are shown in Table 1, and the balance is Fe and inevitable impurity elements. The production steps include: 1) Composite billet assembly: Select two sheets of SA387Gr12CL2 and two sheets of SA240 TP410S material billets. The thickness of the base material SA387Gr12CL2 billet is about 220 - 225 mm, the width is 1920 - 1940 mm, the thickness of the stainless steel billet is about 16 - 18 mm, and the width is 1920 - 1940 mm. Before welding composite, grind the surfaces of the clad material and the base material clean to expose the metal color, and there is no scale, oil stain, etc. on the surface. Stack the composite billet in the thickness direction in the order of base material + clad material + magnesium oxide isolating agent + clad material + base material. The edge of the clad material is about 120 - 140 mm away from the edge of the base material in the width direction, and the geometric shapes of each layer above and below are kept consistent. The welding areas on the four sides of the composite billet are polished to remove rust and oil, and gas shielded welding is used to weld the four sides of the composite billet. After welding, leave a gas hole at the end of the composite plate billet for vacuum pumping treatment. When the vacuum degree of the composite surface reaches below 5.0×10 -2 Pa, keep the vacuum for more than 40 min, and then seal the vacuum pumping pipe using electron beam welding technology; 2) Billet heating: After the composite billet is welded and combined, it is charged into the furnace for heating. The heating temperature is 1160 - 1200 °C, the heating rate is 3.5 min / mm, the total time in the furnace is 540 min, and the furnace outlet temperature is 1180 ± 20 °C; 3) First-stage rolling: The starting rolling temperature is ≥1050°C. The steel plate is rolled in a fully longitudinal or fully transverse manner. The reduction per pass is above 35 mm. The biting speed is 1.3 m / s, and the rolling speed is 2.0 m / s. The final rolling temperature is ≥980°C, and the intermediate rolling thickness is 175 - 180 mm; 4) Second-stage rolling: The starting rolling temperature is 910 - 930°C, the rolling thickness is 121 - 123 mm, the final rolling temperature is 780 - 840°C, and air cooling is carried out after rolling; 5) Piled cooling after rolling: The steel plate is piled and cooled after being taken off the production line. The piling cooling time is ≥48 h; 6) Sheet separation: The edges and ends of the rolled composite plate are cut. The composite plate is separated by flame cutting the four sides; after separation, plasma cutting is used for sizing. 100 - 120 mm is cut from both sides in the width direction, and 300 - 500 mm is cut from each of the head and tail; 7) Heat treatment: The composite plate is heat-treated by quenching + tempering. The quenching temperature is 910 - 940°C, and the time is 2.0 - 2.5 min / mm; the tempering temperature is 710 - 740°C, and the tempering time is 3.0 - 3.5 min / mm; 8) Finishing: The surface of the heat-treated composite plate is cleaned, straightened and leveled, and water polished; the thickness of the upper and lower composite plates is 61 - 62 mm, of which the clad material stainless steel SA240 TP410SL has a thickness of 4.2 - 4.5 mm, and the base material SA387Gr12CL2 has a thickness of 56.5 - 57.5 mm.

[0012] The welding composite process parameters of SA387Gr12CL2 + SA240 TP410S produced in Example 1 are shown in Table 2. The rolling and heat treatment process parameters of the composite plate SA387Gr12CL2 + SA240 TP410S in Example 1 are shown in Tables 3 and 4. In Table 4, the composite plate is first water-cooled in the high-pressure area during quenching, briefly air-cooled after leaving the high-pressure area until the surface temperature returns, and then enters the low-pressure area for water-cooling. The swing cooling time in the low-pressure area is 600 s. The running speed of the steel plate on the roller table in the cooling area is 0.03 m / s, and the temperature after leaving the cooling area is ≤30°C.

[0013] The (56 + 4) mm thick SA387Gr12CL2 + SA240 TP410S stainless steel composite plate produced according to the above process parameters has a bonding rate of 100% and good surface quality. Samples are taken for metallographic structure observation. The base material of the composite plate is tempered bainite structure, and the grain size can reach above grade 9. The bonding surface is tightly bonded, without defects such as pores and inclusions. The yield strength, tensile strength, yield ratio, -34°C impact performance, shear strength, and intergranular corrosion rate of the stainless steel composite plate in Example 1 are tested, and the results are shown in Table 5. The metallographic structure of the base material is as Figure 1 shown, and the morphology of the intergranular corrosion specimen is as Figure 2 shown.

[0014] Table 1 Main Chemical Compositions of the Steel Plate of Composite Plate in Example 1 (wt.%) 。

[0015] Table 2 Welding Composite Process Parameters of Composite Plate Blank in Example 1 。

[0016] Table 3 Rolling Process Parameters of Composite Plate in Example 1 。

[0017] Table 4 Heat Treatment Process Parameters of Composite Plate in Example 1 。

[0018] Table 5 Mechanical Properties of Composite Plate in Example 1 。

[0019] Example 2 A production method of a cryogenic CrMo steel rolled composite plate SA387Gr12CL2 + SA240TP410S, the chemical compositions of its base material SA387Gr12CL2 and clad material SA240 TP410S are shown in Table 6, and the balance is Fe and inevitable impurity elements; the production steps include: 1) Composite billet assembly: Select two billets of SA387Gr12CL2 and SA240 TP410S materials respectively. The thickness of the base material SA387Gr12CL2 billet is about 220 - 225 mm, the width is 1920 - 1940 mm, the thickness of the stainless steel billet is about 16 - 18 mm, and the width is 1920 - 1940 mm. Before welding and composite, grind the surfaces of the clad material and the base material clean and expose the metal color, and there is no scale, oil stain, etc. on the surface. Stack the composite billet in the thickness direction in the order of base material + clad material + magnesium oxide separator + clad material + base material. The edge of the clad material is about 120 - 140 mm away from the edge of the base material in the width direction, and the geometric shapes of each layer above and below are kept consistent. The welding areas on the four sides of the composite billet are polished to remove rust and oil, and the four sides of the composite billet are welded by gas shielded welding. After welding, leave a gas hole at the end of the composite plate blank for vacuum pumping. When the vacuum degree of the composite surface reaches below 5.0×10 -2 Pa, keep the vacuum for more than 40 min, and then seal the vacuum pumping tube by electron beam welding technology; 2) Billet heating: After the composite billet is welded and composite, it is charged into the furnace for heating. The heating temperature is 1160 - 1200 °C, the heating rate is 3.5 min / mm, the total time in the furnace is 535 min, and the furnace outlet temperature is 1180 ± 20 °C; 3) First-stage rolling: The starting rolling temperature is ≥1050°C. The steel plate is rolled in a fully longitudinal or fully transverse manner. The reduction per pass is more than 35 mm, the biting speed is 1.3 m / s, and the rolling speed is 2.0 m / s. The finishing rolling temperature is ≥980°C, and the intermediate rolling thickness is 175 - 180 mm; 4) Second-stage rolling: The starting rolling temperature is 910 - 930°C, the rolling thickness is 121 - 123 mm, the finishing rolling temperature is 780 - 840°C, and air cooling is carried out after rolling; 5) Piled cooling after rolling: Piled cooling is carried out after the steel plate is taken off the production line, and the piled cooling time is ≥48 h; 6) Sheet separation: The edges and ends of the rolled composite plate are cut. The composite plate is separated by flame cutting the four sides; after separation, plasma cutting is used for sizing. 100 - 120 mm is cut from both sides in the width direction, and 300 - 500 mm is cut from each of the head and tail; 7) Heat treatment: The composite plate is heat-treated by quenching + tempering. The quenching temperature is 910 - 940°C, and the time is 2.0 - 2.5 min / mm; the tempering temperature is 710 - 740°C, and the tempering time is 3.0 - 3.5 min / mm; 8) Finishing: The surface of the heat-treated composite plate is cleaned, straightened and leveled, and water polished; the thickness of the upper and lower composite plates is 61 - 62 mm, among which the thickness of the clad stainless steel SA240 TP410SL is 4.2 - 4.5 mm, and the thickness of the base material SA387Gr12CL2 is 56.5 - 57.5 mm.

[0020] The welding composite process parameters of SA387Gr12CL2 + SA240 TP410S produced in Example 2 are shown in Table 7. The rolling and heat treatment production process parameters of the composite plate SA387Gr12CL2 + SA240 TP410S in Example 2 are shown in Tables 8 and 9. In Table 8, quenching is first carried out with water cooling in the high-pressure area, and after leaving the high-pressure area, it is briefly air-cooled until the surface temperature returns, and then it enters the low-pressure area for water cooling. The swing cooling time in the low-pressure area is 600 s, the running speed of the steel plate on the roller table in the cooling area is 0.03 m / s, and the temperature after leaving the cooling area is ≤30°C.

[0021] The (56 + 4) mm thick SA387Gr12CL2 + SA240 TP410S stainless steel composite plate produced according to the above process parameters has a bonding rate of 100% and good surface quality. Samples are taken for metallographic structure observation. The base material of the composite plate is tempered bainite structure, the grain size can reach above grade 9, the bonding surface is tightly bonded, and there are no defects such as pores and inclusions.

[0022] Table 6 Main chemical components (wt.%) of the composite plate steel in Example 2 .

[0023] Table 7 Welding Composite Process Parameters of the Composite Slab in Example 2 。

[0024] Table 8 Rolling Process Parameters of the Composite Plate in Example 2 。

[0025] Table 9 Heat Treatment Process Parameters of the Composite Plate in Example 2 。

[0026] Table 10 Mechanical Properties of the Composite Plate in Example 2 。

[0027] The yield strength, tensile strength, yield ratio, -34°C impact performance, shear strength, and intergranular corrosion rate of the SA387Gr12CL2+SA240 TP410S stainless steel composite plate described in Example 2 were tested, and the results are shown in Table 10.

[0028] Note: In Table 5 and Table 10, a is the thickness of the composite plate; the holding temperature of the simulated post-weld heat treatment process is 690±14°C, the holding time is 20 hours, the sample inlet and outlet furnace temperature ≤ 425°C, and the heating and cooling rate above 425°C is 55~100°C / hour; the intergranular corrosion is carried out by Method E.

Claims

1. A method for producing ultra-low temperature CrMo steel rolled composite plate, characterized in that: The thickness of the produced composite plate is 10~60mm, the width is 1500~3800mm, the chemical composition weight percentage of the base steel is C=0.10~0.14, Si=0.18~0.25, Mn=0.45~0.55, P≤0.008, S≤0.003, Alt=0.02~0.04, Cr=0.90~1.10, Mo=0.50~0.60, Ni=0.12~0.16, the balance is Fe and inevitable impurity elements; the chemical composition weight percentage of the cladding stainless steel is C≤0.08, Si≤1.00, Mn≤1.00, P≤0.035, S≤0.015, Ni≤0.60, Cr=11.5~13.5, the balance is Fe and inevitable impurity elements; The key process steps include: (1) Double-sided symmetrical welding composite: select two CrMo steel and two stainless steel plate blanks, polish one side of the covering material and the base material to reveal the metal color, and stack them in the order of base material + covering material + magnesium oxide isolation agent + covering material + base material. Use gas shielded welding to weld the four sides of the composite blank. After welding, vacuum the space inside the composite blank to a vacuum degree of 5×10 -2 Below Pa, the pressure holding time is ≥40min; (2) Heating: The heating temperature is 1160~1200℃, and the total time in the furnace is ≥500min; (3) First stage rolling: the starting rolling temperature is ≥1050℃, the steel plate is rolled by full rolling or full cross rolling, the single pass reduction is more than 40mm, the steel biting speed is 1.3m / s, and the rolling speed is 2.0m / s; the final rolling temperature is ≥980℃, and the intermediate rolling thickness is the target rolling thickness + 40~80mm; (4) Second stage rolling: starting rolling temperature 910~940℃, final rolling temperature 780~840℃, air cooling after rolling; (5) Heat treatment: The composite plate adopts quenching + tempering heat treatment, the quenching temperature is 910~940℃, the time is 2.0~2.5min / mm; the tempering temperature is 710~740℃, and the tempering time is 3.0~3.5min / mm.

2. The method for producing an ultra-low temperature CrMo steel rolled composite plate according to claim 1, characterized in that: The bonding rate of the produced ultra-low temperature CrMo steel rolled composite plate reaches 100%, the surface quality of the coating is good, and the yield strength of the composite plate at 1 / 2 thickness in the as-supplied state and in the simulated post-weld heat treatment state is ≥290MPa, the tensile strength is 450~585MPa, the yield strength ratio is ≤0.80, the impact energy at -34℃ is ≥200J, the shear strength is>300MPa, and the intergranular corrosion rate is 0.

Images