Production method of rolled composite plate for coal chemical industry

Abstract

The invention discloses a production method of a rolled composite plate for coal chemical industry. The rolled composite plate with the thickness of 10-70 mm and the width of 1500-3000 mm is produced, and base layer steel comprises the following chemical components in percentage by weight: 0.12-0.16% of C, 0.50-0.60% of Si, 0.40-0.65% of Mn, less than or equal to 0.007% of P, less than or equal to 0.003% of S, 0.020-0.045% of Alt, 1.15-1.50% of Cr, 0.50-0.65% 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 is larger than or equal to 310 MPa, the tensile strength is 520-680 MPa, the impact absorption energy at the temperature of-20 DEG C is larger than or equal to 200 J, the shear strength is larger than or equal to 300 MPa, and the intergranular corrosion rate is 0 under the inspection supply state and the simulation postweld heat treatment state.

Description

Technical Field

[0001] This invention belongs to the field of stainless steel composite technology and relates to a method for producing rolled composite plates for coal chemical industry. Background Technology

[0002] In the petrochemical and coal chemical industries, equipment typically operates under high-temperature, high-pressure, and hydrogen-contaminated conditions, requiring container materials to possess high resistance to hydrogen embrittlement, hydrogen delamination, and hydrogen corrosion; simultaneously, they must exhibit high strength, particularly high-temperature strength and low-temperature toughness. To ensure long-term safe operation, the selected materials must meet these requirements. CrMo pressure vessel steel, with its excellent high-temperature strength, resistance to hydrogen corrosion, high-temperature creep resistance, and good low-temperature impact toughness, has become a crucial material for large pressure vessel equipment. In traditional petrochemical equipment production processes, a layer of stainless steel is usually welded onto the inner wall of the equipment to protect it from hydrogen corrosion and acid corrosion during operation, thus extending its service life. Rolled bimetallic composite plates are a new type of energy-saving and environmentally friendly material. They utilize advanced hot-rolling composite technology, with carbon steel or alloy steel as the base layer and stainless steel as the cladding, to achieve a complete metallurgical bond between the base layer and the cladding. Rolled stainless steel composite steel plates fully realize the complementary advantages of materials, possessing both the corrosion resistance, antibacterial properties, and decorative properties of the cladding material, and the good mechanical properties, weldability, formability, ductility, and thermal conductivity of the base material.

[0003] Compared to traditional exploded composite panels, rolled composite panels have the following advantages: they are not affected by the environment, climate, or policies, and can be produced continuously and efficiently, enabling large-scale and rapid delivery; they are produced indoors, resulting in less emissions and pollution, and are environmentally friendly and harmless; they have a complete range of specifications and a wider range of product sizes to choose from, allowing for free design as needed; the composite material and the base material are combined in one piece, resulting in fewer splicing welds and reducing potential quality risks. Summary of the Invention

[0004] This invention aims to provide a method for producing rolled composite plates for coal chemical industry. The produced rolled composite plates achieve a 100% bonding rate, and no delamination or cracking is observed during internal bending, external bending, and lateral bending. The surface quality of the coating is excellent. The composite plates, at half their thickness in both the supplied state and under simulated post-weld heat treatment conditions, exhibit a yield strength ≥310 MPa, tensile strength of 520~680 MPa, elongation ≥20%, impact absorption energy at -20℃ ≥200 J, shear strength ≥310 MPa, and intergranular corrosion rate of 0.

[0005] The technical solution of this invention: A method for producing rolled composite plates for coal chemical industry, wherein the composite plates have a thickness of 10~70mm and a width of 1500~3000mm. The chemical composition (weight percentage) of the base steel is C=0.12~0.16, Si=0.50~0.60, Mn=0.40~0.65, P≤0.007, S≤0.003, Alt=0.020~0.045, Cr=1.15~1.50, Mo=0.50~0.65, Ni=0.12~0.16, with the balance being Fe and unavoidable 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, with the balance being Fe and unavoidable impurity elements; the key process steps include: (1) Double-sided symmetrical welding composite: The cladding material and the substrate are ground clean to expose the metal color. They are stacked in the order of substrate + cladding material + magnesium oxide release agent + cladding material + substrate. The four sides of the composite billet are welded using gas shielded welding. After welding, the hollow part of the composite billet is vacuumed to a vacuum degree of 5×10 -2 For pressure below 40 Pa, the holding time should be ≥40 min; (2) Heating of composite slab: The heating temperature is 1170~1210℃, and the total furnace time is 1~1.2min / mm×composite slab thickness mm; (3) First stage rolling: the initial rolling temperature is ≥1050℃, the steel plate adopts full rolling or full transverse rolling, the single pass reduction is ≥40mm, the bite speed is 1.3m / S, the rolling speed is 2.0 m / S; the final rolling temperature is ≥980℃, and the intermediate rolling thickness is the target rolling thickness +40~80mm. (4) Second stage rolling: initial rolling temperature 900~940℃, final rolling temperature 780~840℃, followed by air cooling; (5) Heat treatment: The composite plate is subjected to quenching and tempering heat treatment. The quenching temperature is 900~930℃ and the quenching time is the thickness of the composite plate mm×(1.8~2.5)min / mm; the tempering temperature is 710~740℃ and the tempering time is the thickness of the composite plate mm×(3.0~3.5)min / mm.

[0006] The rolled composite plate produced according to the technical plan has a bonding rate of 100%. The yield strength at half thickness of the composite plate in the supplied state and the simulated post-weld heat treatment state is ≥310MPa, tensile strength is 520~680MPa, elongation is ≥20%, impact absorption energy at -20℃ is ≥200J, shear strength is ≥300MPa, and intergranular corrosion rate is 0.

[0007] The beneficial effects of this invention are as follows: The symmetrical welding composite method is used for production. Through a process of billet welding composite + vacuuming + controlled rolling + tempering heat treatment, coupled with appropriate composition design, the process is simple, highly operable, and eliminates the need for milling or machining of the substrate, resulting in high production efficiency and low manufacturing costs. The rolling process employs high temperature and high pressure to ensure effective bonding between the base layer and the cladding layer at high temperatures. Simultaneously, controlled rolling in the second stage refines the original grains of the base layer. Finally, quenching and tempering heat treatment gives the composite plate a suitable microstructure, ensuring the strength and ultra-low temperature impact toughness of the steel plate. Attached Figure Description

[0008] Figure 1 This is a morphological diagram of the composite interface structure in Example 1.

[0009] Figure 2 This is a macroscopic morphology diagram of intergranular corrosion in Example 1. Detailed Implementation

[0010] The present invention will be further illustrated by the following examples. Example 1

[0011] A method for producing a rolled composite plate (14Cr1MoR + SA240TP410S) for coal chemical industry, wherein the chemical composition of the base material (14Cr1MoR) and the cladding material (SA240TP410S) is shown in Table 1, with the balance being Fe and unavoidable impurity elements; the production steps include: 1) Composite Billet Assembly: Two sheets each of 14Cr1MoR and SA240 TP410S slabs are selected. The 14Cr1MoR base material is approximately 230-235mm thick and 2000-2020mm wide, while the stainless steel base material is approximately 14.5-15.5mm thick and 1920-1940mm wide. Before welding, the surfaces of the cladding and base material are cleaned to expose the metal's natural color, ensuring no iron oxide scale, oil, or other contaminants remain. The composite billets are stacked in the following order: base material + cladding + magnesium oxide release agent + cladding + base material. In the width direction, the edge of the cladding is approximately 120-140mm away from the edge of the base material, maintaining a consistent geometric shape across all layers. The welding areas on all four sides of the composite billet are ground to remove rust and oil. Gas shielded welding is then used on all four sides of the composite billet. After welding, a vent is left at the end of the composite billet for vacuum treatment. The vacuum level on the composite surface reaches 5.0 × 10⁻⁶. -2 After the pressure drops below 10 Pa, maintain the vacuum for at least 40 minutes, and then seal the vacuum tube using electron beam welding technology.

[0012] 2) Billet heating: After the composite billet is welded and bonded, it is loaded into the furnace for heating. The heating temperature is 1170~1210℃, the heating rate is 1.1min / mm, the total time in the furnace is 490min, and the furnace exit temperature is 1190±10℃.

[0013] 3) First stage rolling: Initial rolling temperature ≥1050℃. The steel plate adopts full longitudinal rolling or full transverse rolling, with a single pass reduction of more than 35mm, a bite speed of 1.3m / s, and a rolling speed of 2.0 m / s. The final rolling temperature ≥980℃, and the intermediate rolling thickness is 190~200mm.

[0014] 4) Second stage rolling: initial rolling temperature 910~930℃, rolling thickness 138~140mm, final rolling temperature 790-840℃, followed by air cooling.

[0015] 5) Post-rolling cooling: After the steel plate is rolled off the production line, it is cooled by stacking for ≥48 hours.

[0016] 6) Sheeting: The rolled composite board is trimmed and the ends are cut. The composite board is sheeted by flame cutting on all four sides; after sheeting, it is cut to length by plasma cutting. In the width direction, the two sides are trimmed by 100-120mm, and the beginning and end are each trimmed by 300-450mm.

[0017] 7) Heat treatment: The composite plate adopts quenching and tempering heat treatment. The quenching temperature is 900~930℃ and the quenching time is the thickness of the composite plate mm × (1.8~2.5) min / mm; the tempering temperature is 710~740℃ and the tempering time is the thickness of the composite plate mm × (3.0~3.5) min / mm.

[0018] 8) Finishing: Clean, straighten and flatten, and water polish the surface of the heat-treated composite plate; the thickness of the upper and lower composite plates is 69~70mm, of which the thickness of the cladding material is stainless steel SA240 TP410SL is 3.1~3.4mm, and the thickness of the base material is 14Cr1MoR 66.5~67.6mm.

[0019] The welding composite process parameters for the 14Cr1MoR+SA240 TP410S produced in Example 1 are shown in Table 2. The rolling and heat treatment process parameters for the 14Cr1MoR+SA240 TP410S composite plate in Example 1 are shown in Tables 3 and 4. In Table 4, the composite plate is first water-cooled in the high-pressure zone, then briefly air-cooled until the surface temperature returns to normal after exiting the high-pressure zone, and then water-cooled in the low-pressure zone. The low-pressure zone oscillating cooling time is 600s, the roller speed of the steel plate in the cooling zone is 0.03m / s, and the temperature exiting the cooling zone is ≤30℃.

[0020] The (66+3)mm thick 14Cr1MoR+SA240 TP410S stainless steel composite plate produced according to the above process parameters achieved a 100% bonding rate and good surface quality. Metallographic observation of samples revealed that the substrate of the composite plate exhibited tempered bainitic structure with a grain size exceeding grade 8. The bonding surfaces were tightly adhered, free from defects such as porosity and inclusions. The yield strength, tensile strength, elongation, -20℃ impact performance, bending, shear strength, and intergranular corrosion rate of the stainless steel composite plate in Example 1 were tested, and the results are shown in Table 5. The metallographic structure of the base material is as follows: Figure 1 As shown, the morphology of the coated intergranular corrosion sample is as follows: Figure 2 As shown.

[0021] Table 1. Main chemical composition (wt.%) of the composite steel plate in Example 1 .

[0022] Table 2. Composite process parameters for welding composite slabs in Example 1. .

[0023] Table 3 Rolling process parameters of the composite plate in Example 1 .

[0024] Table 4 Heat treatment process parameters of the composite plate in Example 1 .

[0025] Table 5 Mechanical properties of the composite plate in Example 1 .

[0026] Example 2 A method for producing a rolled composite plate (14Cr1MoR + SA240TP410S) for coal chemical industry, wherein the chemical composition of the base material (14Cr1MoR) and the cladding material (SA240TP410S) is shown in Table 6, with the balance being Fe and unavoidable impurity elements; the production steps include: 1) Composite Billet Assembly: Two sheets each of 14Cr1MoR and SA240 TP410S slabs are selected. The 14Cr1MoR substrate slab is approximately 148-150mm thick and 1840-1860mm wide, while the stainless steel slab is approximately 17-17.5mm thick and 1740-1760mm wide. Before welding, the surfaces of the cladding and substrate are cleaned to expose the metal's natural color, ensuring no iron oxide scale or oil stains remain. The composite billets are stacked in the following order along the thickness: substrate + cladding + magnesium oxide release agent + cladding + substrate. In the width direction, the edge of the cladding is approximately 120-140mm away from the edge of the substrate, maintaining consistent geometry across all layers. The welding areas on all four sides of the composite billet are ground to remove rust and oil. Gas shielded welding is used on all four sides of the composite billet. After welding, a vent is left at the end of the composite billet for vacuum treatment. The vacuum level on the composite surface reaches 5.0 × 10⁻⁶. -2 After the pressure drops below 10 Pa, maintain the vacuum for at least 40 minutes, and then seal the vacuum tube using electron beam welding technology.

[0027] 2) Billet heating: After the composite billet is welded and bonded, it is loaded into the furnace for heating. The heating temperature is 1170~1200℃, the heating rate is 1.1min / mm, the total time in the furnace is 363min, and the furnace exit temperature is 1180±10℃.

[0028] 3) First stage rolling: Initial rolling temperature ≥1050℃. The steel plate adopts full longitudinal rolling or full transverse rolling, with a single pass reduction of more than 35mm, a bite speed of 1.3m / s, and a rolling speed of 2.0 m / s. The final rolling temperature ≥980℃, and the intermediate rolling thickness is 140~145mm.

[0029] 4) Second stage rolling: initial rolling temperature 890~910℃, rolling thickness 79~80mm, final rolling temperature 780~830℃, followed by air cooling.

[0030] 5) Post-rolling cooling: After the steel plate comes off the production line, it is cooled by stacking for ≥48 hours.

[0031] 6) Sheeting: The rolled composite board is trimmed and the ends are cut. The composite board is sheeted by flame cutting on all four sides; after sheeting, it is cut to length by plasma cutting. In the width direction, the two sides are trimmed by 100-120mm, and the beginning and end are each trimmed by 300-500mm.

[0032] 7) Heat treatment: The composite plate adopts quenching and tempering heat treatment. The quenching temperature is 900~940℃ and the quenching time is the thickness of the composite plate mm × (1.8~2.5) min / mm; the tempering temperature is 710~740℃ and the tempering time is the thickness of the composite plate mm × 3.0~3.5 min / mm.

[0033] 8) Finishing: Clean, straighten and flatten, and water polish the surface of the heat-treated composite plate; the thickness of the upper and lower composite plates is 39.8~40.2mm, of which the thickness of the cladding material is stainless steel SA240 TP410SL is 3.2~3.4mm, and the thickness of the base material is 14Cr1MoR 36.6~36.8mm.

[0034] The welding composite process parameters for the 14Cr1MoR+SA240 TP410S produced in Example 2 are shown in Table 7. The rolling and heat treatment process parameters for the 14Cr1MoR+SA240 TP410S composite plate of Example 2 are shown in Tables 8 and 9. In Table 8, quenching is first performed by water cooling in the high-pressure zone, followed by brief air cooling until the surface temperature returns to normal, and then water cooling in the low-pressure zone. The roller speed of the steel plate in the cooling zone is 0.04 m / s, and the temperature exiting the cooling zone is ≤30℃.

[0035] The (36+3)mm thick 14Cr1MoR+SA240 TP410S stainless steel composite plate produced according to the above process parameters has a 100% bonding rate and good surface quality. Metallographic observation of the sample shows that the substrate of the composite plate is tempered bainitic structure with a grain size of grade 8 or above. The bonding surface is tightly bonded and free of defects such as porosity and inclusions.

[0036] Table 6. Main chemical composition (wt.%) of the composite steel plate in Example 2 .

[0037] Table 7. Composite process parameters for welding composite slabs in Example 2 .

[0038] Table 8 Rolling process parameters of the composite plate in Example 2 .

[0039] Table 9 Heat treatment process parameters of the composite plate in Example 2 .

[0040] Table 10 Mechanical properties of the composite plate in Example 2 .

[0041] The yield strength, tensile strength, elongation, -20℃ impact performance, bending, shear strength and intergranular corrosion rate of the 14Cr1MoR+SA240 TP410S stainless steel composite plate described in Example 2 were tested, and the results are shown in Table 10.

[0042] Notes: The simulated post-weld heat treatment process in Tables 5 and 10 has a holding temperature of 690±14℃ and a holding time of 22 hours. The sample temperature entering and exiting the furnace is ≤425℃, and the heating and cooling rate above 425℃ is 55~100℃ / hour. Intergranular corrosion adopts method E in GB / T4334.

Claims

1. A method for producing rolled composite plates for coal chemical industry, characterized in that: The composite plates produced have a thickness of 10~70mm and a width of 1500~3000mm. The chemical composition (by weight percentage) of the base steel is C=0.12~0.16, Si=0.50~0.60, Mn=0.40~0.65, P≤0.007, S≤0.003, Alt=0.020~0.045, Cr=1.15~1.50, Mo=0.50~0.65, Ni=0.12~0.16, with the balance being Fe and unavoidable impurity elements. The chemical composition (by 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, with the balance being Fe and unavoidable impurity elements. Key process steps include: (1) Double-sided symmetrical welding composite: Select two base plate and two cladding plates. Grind one side of the cladding and the base plate clean to expose the metal color. Stack them in the order of base plate + cladding + magnesium oxide release agent + cladding + base plate. Weld the four sides of the composite plate with gas shielded welding. After welding, vacuum treatment is performed on the inner cavity of the composite plate to a vacuum degree of 5×10 -2 For pressure below 10 Pa, the holding time should be ≥40 min; (2) Heating of composite slab: The heating temperature is 1180~1210℃, and the total time in the furnace is ≥500min; (3) First stage rolling: the initial rolling temperature is ≥1050℃, the steel plate adopts full rolling or full transverse rolling, the single pass reduction is ≥40mm, the bite speed is 1.3m / s, the rolling speed is 2.0 m / s; the final rolling temperature is ≥980℃, and the intermediate rolling thickness is the target rolling thickness +50~80mm. (4) Second stage rolling: initial rolling temperature 900~940℃, final rolling temperature 780~840℃, followed by air cooling; (5) Heat treatment: The composite plate is subjected to quenching and tempering heat treatment. The quenching temperature is 900~930℃ and the quenching time is the thickness of the composite plate mm×(1.8~2.5)min / mm; the tempering temperature is 710~740℃ and the tempering time is the thickness of the composite plate mm×(3.0~3.5)min / mm.

2. The method for producing a rolled composite plate for coal chemical industry according to claim 1, characterized in that: The produced rolled composite plate for coal chemical industry has a 100% bonding rate and good coating surface quality. The yield strength at half thickness of the composite plate in the supplied state and the simulated post-weld heat treatment state is ≥310MPa, the tensile strength is 520~680MPa, the impact absorption energy at -20℃ is ≥200J, the shear strength is ≥300MPa, and the intergranular corrosion rate is 0.

Images