Rolled extra-thick stainless steel composite plate and production method thereof

Abstract

The invention discloses a rolled extra-thick stainless steel composite plate and a production method thereof. Base layer steel comprises the following chemical components in percentage by weight: 0.12-0.16% of C, 0.18-0.30% of Si, 1.30-1.50% of Mn, less than or equal to 0.012% of P, less than or equal to 0.003% of S, 0.02-0.04% of Alt, 0.15-0.25% of Cr, 0.50-0.60% of Mo, 0.55-0.65% of Ni, less than or equal to 0.10% of Cu, less than or equal to 0.02% of Nb, less than or equal to 0.0010% of B and the balance of Fe and inevitable impurity elements. The cladding stainless steel comprises the following chemical components in percentage by weight: less than or equal to 0.03% of C, less than or equal to 0.75% of Si, less than or equal to 2.00% of Mn, less than or equal to 0.035% of P, less than or equal to 0.015% of S, 8.0-12.0% of Ni, 18.0-20.0% of Cr, less than or equal to 0.10% of N and the balance of Fe and inevitable impurity elements; the process route comprises the steps of blank welding compounding, vacuumizing, controlled rolling and quenched-tempered heat treatment. The SA533B CL1 + SA240304L stainless steel composite plate with the thickness of 62-69 mm is produced, the inspection yield strength is larger than 345 MPa, the tensile strength is larger than 550 MPa, the impact energy at the temperature of 10 DEG C is larger than or equal to 200 J, the shear strength is larger than 310 MPa, and the intergranular corrosion crack rate is 0.

Description

Technical Field

[0001] The invention belongs to the technical field of stainless steel cladding, and relates to a rolled extra-thick stainless steel clad plate and a production method thereof. Background Art

[0002] Rolled bimetallic clad plate is a new energy-saving and environmentally friendly material. It features a carbon steel base and a stainless steel cladding layer, achieved through state-of-the-art hot-rolling cladding technology, achieving a complete metallurgical bond between the base and cladding layers. Stainless steel clad plate utilizes a carbon steel or alloy steel base and stainless steel cladding layers, achieving a high-strength metallurgical bond between the two materials. The base layer provides strength, while the cladding layer ensures corrosion resistance, cleanability, wear resistance, aesthetics, and longevity. Stainless steel clad plate is used in the manufacture of various high- and low-pressure corrosion-resistant vessels, road and bridge molds, and linings. Compared to conventional processes such as additive manufacturing and coating, its performance and lifespan are significantly improved. Hot-rolled stainless steel clad plate utilizes industrial continuous production, eliminating the impact of factors such as climatic conditions and uneven explosive forces that can occur during explosive cladding. This results in higher bond strength (above 300 MPa) and 100% bond rate, ensuring consistent product quality. Furthermore, process technologies such as temperature control, rolling control, cooling control, and heat treatment enhance the mechanical properties of the stainless steel clad plate.

[0003] Hot-rolled stainless steel composite plate products have the following characteristics: (1) Hot-rolled stainless steel composite plate fully realizes the complementary advantages of materials, and has both the corrosion resistance, corrosion resistance, antibacterial and decorative properties of the coating material, and the good mechanical properties, weldability, formability, drawability and thermal conductivity of the base material. (2) Hot-rolled stainless steel composite plate can reduce the consumption of precious metals and achieve a perfect combination of low cost and high performance. (3) The coating thickness, base plate thickness and material can be freely combined according to user needs, further reducing the user's use cost. (4) The hot-rolled composite production process uses large-scale medium plate rolling mills and hot rolling mills for production, so the production efficiency is high. Compared with the explosive composite method, it can be continuously produced without weather restrictions and has the ability to quickly supply large quantities, which is conducive to accelerating the user's project progress. Summary of the Invention

[0004] The present invention provides a rolled, extra-thick stainless steel composite plate and a production method thereof, particularly a method for producing a rolled stainless steel composite plate comprising SA533B CL1 and SA240 304L. This method utilizes a process of billet welding, vacuuming, controlled rolling, and quenching and tempering heat treatment, along with appropriate component design. The resulting extra-thick rolled stainless steel composite plate achieves a 100% bonding rate and exhibits no delamination or cracking during inward, outward, or lateral bending tests. The composite plate exhibits a yield strength greater than 345 MPa, a tensile strength greater than 550 MPa, an impact energy at 10°C greater than 200 J, a shear strength greater than 310 MPa, and a zero intergranular corrosion cracking rate.

[0005] The technical solution of the present invention: A rolled extra-thick stainless steel composite plate, wherein the chemical composition weight percentage of the base steel is C=0.12~0.16, Si=0.18~0.30, Mn=1.30~1.50, P≤0.012, S≤0.003, Alt=0.02~0.04, Cr=0.15~0.25, Mo=0.50~0.60, Ni=0.55~0.65, Cu≤0.10, Nb≤0.02, B≤0.0010, and the remainder is Fe and unavoidable impurity elements; the chemical composition weight percentage of the cladding stainless steel is C≤0.03, Si≤0.75, Mn≤2.00, P≤0.035, S≤0.015, Ni=8.0~12.0, Cr=18.0~20.0, N≤0.10, and the balance is Fe and unavoidable impurity elements; the yield strength of the composite plate is greater than 345MPa, the tensile strength is greater than 550MPa, the impact energy at 10℃ is greater than 200J, the shear strength is greater than 310MPa, and the intergranular corrosion crack rate is 0.

[0006] A method for rolling extra-thick stainless steel composite plates, the production process route is: billet welding composite + vacuuming + controlled rolling + quenching and tempering heat treatment, the key process steps are: 1) Composite billet: Double-sided symmetrical welding is used for composite. Two SA533B CL1 and two stainless steel sheet billets are selected. One side of the covering material and the base material are polished clean to reveal the metal color. The billets are stacked in the order of base material + covering material + magnesium oxide separator + covering material + base material. The four sides of the composite billet are welded by gas shielded welding. After welding, the interior of the composite billet is vacuumed to a vacuum degree of 5×10 -2 Below Pa, pressure holding time ≥40min; 2) Billet heating: heating temperature is 1210~1250℃, total furnace time is ≥500min; 3) First stage rolling: the starting rolling temperature is ≥1050℃. The steel plate adopts full rolling or full cross rolling method, the single pass reduction is more than 35mm, the final rolling temperature is ≥980℃, and the intermediate rolling thickness is 175~190mm; 4) Second stage rolling: starting rolling temperature 940~960℃, rolling thickness 124~138mm, finishing rolling temperature 790-850℃, air cooling after rolling; 5) Post-rolling cooling: The steel plate is cooled after rolling off the production line, and the cooling time is ≥48h; 6) Heat treatment: The composite plate adopts quenching + tempering heat treatment, the quenching temperature is 880~920℃, the time is 1.5~2.0min / mm; the tempering temperature is 660~700℃, and the tempering time is 2.5~3.0min / mm; 7) Finishing: The heat-treated composite panels are trimmed and cut, and the four sides of the composite panels are cut by flame. After separation, plasma cutting is used to cut the panels to length. The thickness of the upper and lower composite panels is 62-69 mm, of which the thickness of the cladding material 304L stainless steel is 6.0-7.6 mm, and the thickness of the base material SA533B CL1 is 56.0-62.5 mm.

[0007] The present invention adopts a symmetrical welding composite method for production, which has a simple process and strong operability. It does not require milling, cutting and other processes on the substrate, has high production efficiency and low manufacturing cost. The rolling adopts "high temperature and large reduction" to ensure the effective composite of the base layer and the coating in the high temperature stage. At the same time, the two-stage rolling is controlled to refine the original grains of the base layer. Finally, through the quenching + tempering heat treatment, the composite plate obtains a suitable structure to ensure the strength and impact toughness of the steel plate. The extra-thick rolled stainless steel composite plate produced by the present invention has a bonding rate of 100%, and no delamination and cracking are found in the inspection of inner bending, outer bending and side bending. The composite plate has a yield strength of >345MPa, a tensile strength of >550MPa, an impact energy of 10℃ ≥200J, a shear strength of >310MPa, and an intergranular corrosion crack rate of 0. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a typical metallographic structure photo of the composite plate produced in Example 1.

[0009] Figure 2 This is the macroscopic morphology of intergranular corrosion in Example 1. DETAILED DESCRIPTION Example

[0010] A super-thick rolled stainless steel composite plate SA533B CL1 + SA240 304L and a production method thereof. The chemical compositions of the base material SA533B CL1 and the cladding material SA240 304L are shown in Table 1, with the remainder being Fe and unavoidable impurity elements. The production steps include: 1) Composite assembly: Two SA533B CL1 and two SA240 304L stainless steel sheet blanks are selected. The thickness of the base material SA240 304L sheet blank is about 220~225mm and the width is 1980~2000mm. The thickness of the stainless steel sheet blank is about 28~29mm and the width is 1860~1870mm. Before welding and cladding, the surface of the covering material and the base material are polished clean to expose the original color of the metal. There is no iron oxide scale, oil stain, etc. on the surface. The thickness direction of the composite blank is stacked in the order of base material + covering material + magnesium oxide isolation agent + covering material + base material. The edge of the covering material is about 120~140mm away from the edge of the base material in the width direction. The upper and lower layers keep the same geometric shape. The welding area on the four sides of the composite blank is polished to remove rust and oil. The four sides of the composite blank are welded by gas shielded welding. After welding, an air hole is left at the end of the composite sheet blank for vacuum treatment. When the vacuum degree of the composite surface reaches 5.0×10-2 After the temperature drops below Pa, maintain the vacuum for more than 40 minutes, and then seal the vacuum tube using electron beam welding technology; 2) Billet heating: After the composite billet is welded and composited, it is heated in a furnace at a temperature of 1220±10℃, a heating rate of 3.5min / mm, a total furnace time of 550min, and a furnace exit temperature of 1230±10℃; 3) First stage rolling: the starting rolling temperature is ≥1050℃. The steel plate adopts full longitudinal rolling or full transverse rolling method, the single pass reduction is more than 35mm, the final rolling temperature is ≥980℃, and the intermediate rolling thickness is 175~180mm; 4) Second stage rolling: starting rolling temperature 940~960℃, rolling thickness 124~126mm, finishing rolling temperature 790-850℃, air cooling after rolling; 5) Post-rolling cooling: The steel plate is cooled after rolling off the production line, and the cooling time is ≥48h; 6) Heat treatment: The composite plate adopts quenching + tempering heat treatment, the quenching temperature is 880~920℃, the time is 1.5~2.0min / mm; the tempering temperature is 660~700℃, and the tempering time is 2.5~3.0min / mm; 7) Finishing: The heat-treated composite panels are trimmed and cut. The panels are then separated using flame cutting on all four sides. After separation, they are cut to length using plasma cutting. The width is trimmed by 100-120mm on both sides, with the head and tail trimmed by 300-500mm each. After separation, the composite panels are cleaned, straightened, and polished. The thickness of the upper and lower composite panels is 63-64mm, with the cladding material, stainless steel 304L, being 6.3-6.6mm thick, and the base material, SA533B CL1, being 56.5-57.5mm thick.

[0011] The welding process parameters of SA533B CL1+SA240 304L produced in Example 1 are shown in Table 2, and the key production process parameters of the composite plate SA533B CL1+SA240 304L in Example 1 are shown in Table 3 and Table 4.

[0012] The (56+6)mm thick SA533B CL1+SA240 304L stainless steel composite plate produced according to the above process parameters has a bonding rate of 100%. The metallographic structure of the sample was observed. The base material of the composite plate is a mixed structure of acicular ferrite + granular bainite, with a grain size of more than 11 levels. The bonding surface is tightly bonded without defects such as pores and inclusions. Figure 1 The yield strength, tensile strength, yield strength ratio, 10°C impact performance, shear strength, and intergranular corrosion rate of the SA533B CL1 + SA240 304L stainless steel composite plate described in Example 1 were tested. The results are shown in Table 5. The morphology of the intergranular corrosion specimens is as follows: Figure 2 shown.

[0013] Table 1 Main chemical composition of composite steel plate of Example 1 (wt.%) .

[0014] Table 2 Example 1 SA533B CL1 + SA240 304L composite welding process parameters .

[0015] Table 3 Rolling process parameters of composite plate SA533B CL1+SA240 304L in Example 1 .

[0016] Table 4 Heat treatment process parameters of composite board SA533B CL1+SA240 304L in Example 1 .

[0017] Table 5 Mechanical properties of the composite plate of Example 1 .

[0018] In Table 5, a is the thickness of the composite plate; the simulated post-weld heat treatment process is as follows: the holding temperature is 595-620°C, the holding time is 26 hours, the sample in and out of the furnace temperature is ≤425°C, and the heating and cooling rate above 425°C is ≤55°C / hour.

[0019] Example 2: An extra-thick rolled stainless steel composite plate SA533B CL1 + SA240 304L and a production method thereof. The chemical compositions of the base material SA533B CL1 and the cladding material SA240 304L are shown in Table 6, with the remainder being Fe and unavoidable impurity elements. The production steps include: 1) Composite assembly: Two SA533B CL1 and two SA240 304L stainless steel sheet blanks are selected. The thickness of the base material SA240 304L sheet blank is about 248~250mm and the width is 1980~2000mm. The thickness of the stainless steel sheet blank is about 28~29mm and the width is 1860~1870mm. Before welding and cladding, the surface of the covering material and the base material are polished clean to expose the original color of the metal. There is no iron oxide scale, oil stain, etc. on the surface. The thickness direction of the composite blank is stacked in the order of base material + covering material + magnesium oxide isolation agent + covering material + base material. The edge of the covering material is about 120~140mm away from the edge of the base material in the width direction. The upper and lower layers keep the same geometric shape. The welding area on the four sides of the composite blank is polished to remove rust and oil. The four sides of the composite blank are welded by gas shielded welding. After welding, an air hole is left at the end of the composite sheet blank for vacuum treatment. When the vacuum degree of the composite surface reaches 5.0×10 -2After the temperature drops below Pa, maintain the vacuum for more than 40 minutes, and then seal the vacuum tube using electron beam welding technology; 2) Billet heating: After the composite billet is welded and composited, it is heated in a furnace at a temperature of 1220±10℃, a heating rate of 3.5min / mm, a total furnace time of 550min, and a furnace exit temperature of 1220±10℃; 3) First stage rolling: the starting rolling temperature is ≥1050℃. The steel plate adopts full longitudinal rolling or full transverse rolling method, the single pass reduction is more than 35mm, the final rolling temperature is ≥980℃, and the intermediate rolling thickness is 185~190mm; 4) Second stage rolling: starting rolling temperature 940~960℃, rolling thickness 138~140mm, finishing rolling temperature 790-850℃, air cooling after rolling; 5) Post-rolling cooling: The steel plate is cooled after rolling off the production line, and the cooling time is ≥48h; 6) Heat treatment: The composite plate adopts quenching + tempering heat treatment, the quenching temperature is 880~920℃, the time is 1.5~2.0min / mm; the tempering temperature is 660~700℃, and the tempering time is 2.5~3.0min / mm; 7) Finishing: The heat-treated composite panels are trimmed and cut. The panels are then separated using flame cutting on all four sides. After separation, they are cut to length using plasma cutting. The width is trimmed by 100-120mm on both sides, with the head and tail trimmed by 300-500mm each. After separation, the composite panels are cleaned, straightened, and polished. The thickness of the upper and lower composite panels is 69-70mm, with the cladding material, stainless steel 304L, being 7.2-7.6mm thick, and the base material, SA533B CL1, being 62.5-63.0mm thick.

[0020] The welding process parameters of SA533B CL1+SA240 304L produced in the embodiment are shown in Table 7, and the key production process parameters of the composite plate SA533B CL1+SA240 304L in the embodiment are shown in Tables 8 and 9.

[0021] The (62+7) mm thick SA533B CL1+SA240 304L stainless steel composite plate produced according to the above process parameters had a bonding rate of 100%. Samples were taken for metallographic observation. The base material of the composite plate had a mixed structure of acicular ferrite and granular bainite, and the bonding surface was tightly bonded without defects such as pores and inclusions. The yield strength, tensile strength, yield strength ratio, 10°C impact resistance, shear strength, and intergranular corrosion rate of the SA533B CL1+SA240 304L stainless steel composite plate described in Example 2 were tested, and the results are shown in Table 10.

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

[0023] Table 7 Example 2 SA533B CL1 + SA240 304L composite welding process parameters .

[0024] Table 8 Rolling process parameters of composite plate SA533B CL1+SA240 304L in Example 2 .

[0025] Table 9 Heat treatment process parameters of composite board SA533B CL1+SA240 304L in Example 2 .

[0026] Table 10 Mechanical properties of the composite plate of Example 2 .

[0027] In Table 10, a is the thickness of the composite plate; the simulated post-weld heat treatment process is as follows: the holding temperature is 595-620°C, the holding time is 26 hours, the sample in and out of the furnace temperature is ≤425°C, and the heating and cooling rate above 425°C is ≤55°C / hour.

Claims

1. A rolled extra-thick stainless steel composite plate, characterized in that: The chemical composition weight percentage of the base steel is C=0.12~0.16, Si=0.18~0.30, Mn=1.30~1.50, P≤0.012, S≤0.003, Alt=0.02~0.04, Cr=0.15~0.25, Mo=0.50~0.60, Ni=0.55~0.65, Cu≤0.10, Nb≤0.02, B≤0.0010, and the balance is Fe and unavoidable impurity elements; The chemical composition weight percentage of the layer stainless steel is C≤0.03, Si≤0.75, Mn≤2.00, P≤0.035, S≤0.015, Ni=8.0~12.0, Cr=18.0~20.0, N≤0.10, and the balance is Fe and unavoidable impurity elements; the yield strength of the composite plate is greater than 345MPa, the tensile strength is greater than 550MPa, the impact energy at 10℃ is greater than 200J, the shear strength is greater than 310MPa, and the intergranular corrosion crack rate is 0.

2. A method for producing a rolled extra-thick stainless steel composite plate, the production process route is: billet welding composite + vacuuming + controlled rolling + quenching and tempering heat treatment, characterized in that The key process steps are: 1) Composite: Double-sided symmetrical welding composite is adopted. Two SA533B CL1 and two stainless steel plate blanks are selected. One side of the covering material and the base material is polished clean to reveal the metal color. The composite blanks are stacked in the order of base material + covering material + magnesium oxide isolation agent + covering material + base material. The four sides of the composite blank are welded by gas shielded welding. After welding, the air inside the composite skin is vacuumed, and the vacuum degree reaches 5×10 -2 Below Pa, the pressure holding time is ≥40min; 2) Heating: Heating temperature is 1210~1250℃, total furnace time is ≥500min; 3) First stage rolling: the starting rolling temperature is ≥1050℃. The steel plate adopts full rolling or full cross rolling method, the single pass reduction is more than 40mm, the final rolling temperature is ≥980℃, and the intermediate rolling thickness is 175~180mm; 4) Second stage rolling: starting rolling temperature 940~960℃, rolling thickness 124~138mm, final rolling temperature 790-850℃, air cooling after rolling; 5) Post-rolling cooling: The steel plate is cooled after rolling off the production line, and the cooling time is ≥48h; 6) Heat treatment: The composite plate adopts quenching + tempering heat treatment, the quenching temperature is 880~920℃, the time is 1.5~2.0min / mm; the tempering temperature is 660~700℃, and the tempering time is 2.5~3.0min / mm; 7) Finishing: The heat-treated composite plate is trimmed and cut, and the four sides of the composite plate are cut by flame. After separation, plasma cutting is used to cut the length. The thickness of the upper and lower composite plates is 62~69mm, of which the thickness of the cladding stainless steel 304L is 6.0~7.6mm, and the thickness of the base material SA533B CL1 is 56.0~62.5mm.

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