Low-nickel low-cost chromium-based stainless steel plate and production method thereof

Abstract

The invention discloses a low-nickel low-cost chromium-based stainless steel plate which comprises the following chemical components in percentage content: 0.02 to 0.05 percent of C, 0.20 to 0.50 percent of Si, 0.20 to 0.50 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.003 percent of S, 5.00 to 7.00 percent of Ni, 20.00 to 25.00 percent of Cr, 0.80 to 1.00 percent of Co, 0.020 to 0.050 percent of Nb, 0.020 to 0.050 percent of Ti, 0.20 to 0.60 percent of Mo, 0.020 to 0.050 percent of Al, 0.0010 to 0.0030 percent of B and the balance of Fe and other inevitable impurities. The production method comprises the procedures of steelmaking, continuous casting, heating rolling and heat treatment. The thickness of the steel plate is 20-50 mm, the yield strength is larger than or equal to 300 MPa, the tensile strength is larger than or equal to 520 MPa, the pitting corrosion resistance equivalent PREN is larger than or equal to 40, and corrosion resistance is good.

Description

Technical Field

[0001] The invention belongs to the technical field of steel plate production, and in particular relates to a low-nickel, low-cost chromium-based stainless steel plate and a production method thereof. Background Art

[0002] With the rapid development of science and technology in human society, more and more steel products have been developed, and the scope of use of steel has become more and more extensive, especially stainless steel, which has entered all aspects of human life due to its good corrosion resistance and high temperature performance. At present, stainless steel has occupied a dominant position in the manufacture of kitchenware and tableware, and is widely used in the manufacture of kitchen utensils such as pots and pans, oven trays, and grills, as well as various tableware such as knives, forks, and spoons. Stainless steel is also widely used in the manufacture of various equipment and parts, such as pumps, valves, pipes, pressure vessels, etc. Due to its excellent corrosion resistance, it is also one of the important materials in industries such as chemical, pharmaceutical and food processing.

[0003] Compared with ordinary steel, stainless steel has a higher content of precious metals such as Ni, Cr, and Mo, especially the high content of precious metal nickel, which makes the production cost high. Therefore, stainless steel can only be used in key parts, surfaces, or small parts with complex structures of equipment. Therefore, reducing the content of precious metals and reducing production costs can expand its application range. The development of low-nickel and low-cost chromium-based stainless steel has important social and economic benefits. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a low-nickel, low-cost chromium-based stainless steel plate and a production method thereof. The steel plate has a thickness of 20 to 50 mm, a yield strength of ≥300 MPa, a tensile strength of ≥520 MPa, a pitting resistance equivalent PREN of ≥40, good corrosion resistance, and a low nickel content and production cost. The steel plate can be widely used in various structural engineering projects with high requirements for corrosion resistance and large usage.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A low-nickel, low-cost chromium-based stainless steel plate, whose chemical composition and weight percentage are C: 0.02-0.05%, Si: 0.20-0.50%, Mn: 0.20-0.50%, P≤0.015%, S≤0.003%, Ni: 5.00-7.00%, Cr: 20.00-25.00%, Co: 0.80-1.00%, Nb: 0.020-0.050%, Ti: 0.020-0.050%, Mo: 0.20-0.60%, Al: 0.020-0.050%, B: 0.0010-0.0030%, and the rest are Fe and other inevitable impurities.

[0006] The role and proportion of each element in the steel plate of the present invention are as follows: C: 0.02~0.05%. Carbon has a significant effect on various properties of steel, especially the strength, impact toughness and welding performance of steel. The low carbon content in stainless steel is mainly to prevent carbon from combining with chromium, thereby preventing the appearance of chromium-poor areas at the grain boundaries, greatly reducing corrosion resistance, and preventing the formation of chromium carbides with chromium, consuming chromium and reducing the effective chromium content of steel, thereby reducing the corrosion resistance of steel.

[0007] Si: 0.20-0.50%. Silicon is the main reducing agent and deoxidizer in the steelmaking process. Silicon can significantly improve the elastic limit, yield point and tensile strength of steel. However, when the silicon content exceeds 0.50%, the toughness of the steel will be reduced, and the welding performance of the steel will be reduced.

[0008] Mn: 0.20-0.50%. Manganese is cheap and is a good deoxidizer and desulfurizer. It can increase the toughness and strength of steel, while improving the hardenability and hot working properties of steel. However, if the manganese content is too high, it will weaken the corrosion resistance of steel, reduce welding performance, and aggravate the segregation of continuous casting billets.

[0009] P≤0.015%. Generally speaking, phosphorus is a harmful element in steel. It increases the cold brittleness of steel, reduces its plasticity, and deteriorates its cold bending performance. Under the condition of controlling the cost reasonably, the phosphorus content should be reduced as much as possible.

[0010] S≤0.003%. Sulfur is also a harmful element in steel. It increases the hot brittleness of steel and reduces the ductility and toughness of steel. The sulfur content in steel should be reduced as much as possible under economic benefits.

[0011] Ni: 5.00-7.00%. Nickel can improve the strength of steel, and also enhance its plasticity and toughness. It is an important alloying element in stainless steel. However, metallic nickel is a scarce resource and is expensive. Therefore, the nickel content should be reduced as much as possible while ensuring the final performance of the steel.

[0012] Cr: 20.00~25.00%. A small amount of chromium can improve the strength and hardenability of the steel plate. It is one of the most important elements in stainless steel. Therefore, it needs to be added to a certain content to make the steel plate corrosion-resistant.

[0013] Co: 0.80~1.00%. The main function of cobalt in steel is to refine the grains, improve thermal strength, increase the coercive force of magnetic steel, and have a good effect on magnetism. It can refine the grains of steel and reduce the overheating tendency of steel.

[0014] Nb: 0.020-0.050%. Niobium can promote grain refinement of steel microstructure, while improving strength and toughness. Niobium can effectively refine the microstructure by inhibiting austenite recrystallization during controlled rolling, and improve the hardenability of steel through precipitation strengthening, while reducing overheating sensitivity and temper brittleness of steel.

[0015] Ti: 0.020-0.050%. Titanium is a strong carbonitride-forming element. Carbonitride has a high melting point and can hinder the growth of austenite grains during heating. It can also refine the grains and improve the welding performance of steel plates.

[0016] Mo: 0.20-0.60%. Molybdenum in steel can greatly improve the hardenability and heat resistance of the steel plate, prevent temper brittleness, increase remanence and coercive force, and at the same time improve the corrosion resistance of the steel plate and prevent pitting tendency.

[0017] Al: 0.020-0.050%. Aluminum is a commonly used deoxidizer in steel. Adding a small amount of aluminum to steel can refine the grains and improve impact toughness. Aluminum also has antioxidant and corrosion resistance. Too high a content will affect the hot working properties, welding properties, and cutting properties of steel.

[0018] B: 0.0010~0.0030%. Boron in steel can significantly improve the hardenability of steel, thereby improving the strength and hardness of steel. This is because boron atoms can effectively pin on the austenite grain boundaries, hindering grain growth, thereby refining the grains, increasing the hardness of the material, and significantly improving the corrosion resistance of steel. Therefore, adding an appropriate amount of boron.

[0019] Furthermore, the thickness of the steel plate of the present invention is 20 to 50 mm.

[0020] Furthermore, the steel plate of the present invention has a yield strength of ≥300 MPa, a tensile strength of ≥520 MPa, a pitting resistance equivalent PREN of ≥40, and good corrosion resistance.

[0021] Furthermore, the method for producing the steel plate with ultra-low yield ratio and excellent ductility of the present invention comprises steelmaking, continuous casting, hot rolling and heat treatment processes.

[0022] Preferably, in the steelmaking process of the present invention, the qualified molten steel smelted in the primary refining furnace is transferred to the LF furnace for refining, the refining time in the LF furnace refining process is ≥60min, ensuring that argon blowing is good throughout the whole process, the white slag is maintained for ≥20min, and alloys are added in batches after deoxidation to make the alloy content within the required range of smelting composition; the qualified molten steel refined in the LF is hoisted into a VOD furnace for oxygen blowing and decarburization within the required range of composition, and then vacuum degassing treatment is carried out, the vacuum holding time is ≥20min, and soft blowing is carried out for 8-12min after vacuum degassing treatment to promote the floating and removal of non-metallic inclusions.

[0023] Preferably, in the continuous casting process of the present invention, qualified molten steel is cast into wide and thick slabs with a thickness of 200 to 250 mm through a large thick slab continuous casting machine, and the superheat is controlled within the range of 15 to 25° C. during the casting process.

[0024] Preferably, in the heating rolling process of the present invention, the slab is heated in a continuous furnace, the maximum heating temperature is 1230°C, the temperature in the insulation stage is 1180-1210°C, the total heating time is ≥15min / cm, the starting rolling temperature during rolling is 1060-1150°C, the reduction rate for each pass is 10-15%, the final rolling temperature is 880-950°C, and it is air-cooled to room temperature after rolling.

[0025] Preferably, in the heat treatment process of the present invention, the solution quenching temperature is 900-950°C, the total heating time is 3.0-4.0 min / mm, and after being taken out of the furnace, it is quickly water-cooled to ≤300°C and then air-cooled to room temperature to obtain the steel plate.

[0026] The present invention reduces the generation of internal inclusions in molten steel and improves the purity of molten steel by controlling the LF furnace refining and VOD furnace vacuum treatment processes; then, it continuously casts the molten steel into wide and thick slabs with excellent internal quality, and adopts appropriate rolling technology and solution heat treatment technology to make the steel plates have good comprehensive properties.

[0027] The beneficial effects of adopting the above technical solution are: The steel plate produced by the present invention has uniform and dense internal structure, high strength, good corrosion resistance, low production cost due to small amount of precious metal nickel added, and a steel plate thickness specification of 20 to 50 mm, a yield strength of ≥300 MPa, a tensile strength of ≥520 MPa, a pitting resistance equivalent PREN of ≥40, and good corrosion resistance. The steel plate can be widely used in key equipment with high strength requirements and high corrosion resistance requirements, and can also replace imports to reduce the import price of similar domestic steel plates. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The following embodiments are further illustrated. Example 1

[0029] The thickness specification of the steel plate in this embodiment is 45 mm, and its chemical composition and its weight percentage are C: 0.03%, Si: 0.20%, Mn: 0.50%, P: 0.011%, S: 0.002%, Ni: 7.00%, Cr: 24.12%, Co: 0.86%, Nb: 0.043%, Ti: 0.038%, Mo: 0.41%, Al: 0.020%, B: 0.0022%, and the rest are Fe and other unavoidable impurities.

[0030] The production method of the steel plate in this embodiment includes steelmaking, continuous casting, hot rolling, and heat treatment processes. The specific production process steps are as follows: (1) Steelmaking process: The qualified molten steel from the primary refining furnace is transferred to the LF furnace for refining. The total refining time in the LF furnace is 73 minutes. The argon blowing is good during the process. The white slag is kept for 37 minutes. After deoxidation, alloys are added in batches to meet the smelting composition requirements. The qualified molten steel from the LF refining is hoisted into the VOD furnace for oxygen blowing and carbon removal to meet the smelting composition requirements, and then vacuum degassing is carried out. The vacuum is maintained for 24 minutes. After the vacuum degassing treatment, soft blowing is carried out for 10 minutes to promote the floating and removal of non-metallic inclusions.

[0031] (2) Continuous casting process: The qualified molten steel is cast into 240mm thick continuous casting billets through a large slab continuous casting machine. During the casting process, the molten steel is superheated to 25°C to ensure that the billets have good internal quality.

[0032] (3) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a maximum heating temperature of 1230°C, a holding stage temperature of 1180°C, a total heating time of 360 min, a starting rolling temperature of 1140°C, a reduction rate of 13% per pass, a final rolling temperature of 950°C, and air cooling to room temperature after rolling.

[0033] (4) Heat treatment process: solution quenching temperature is 940°C, total heating time is 135 min, after being taken out of the furnace, it is quickly water-cooled to 260°C, and then air-cooled to room temperature to obtain the steel plate.

[0034] The steel plate of this embodiment has a yield strength of 318 MPa throughout the entire plate thickness, a tensile strength of 520 MPa, a pitting resistance equivalent PREN≥47, good corrosion resistance, and excellent overall performance. Example 2

[0035] The thickness specification of the steel plate in this embodiment is 40 mm, and its chemical composition and its weight percentage are C: 0.02%, Si: 0.26%, Mn: 0.28%, P: 0.011%, S: 0.001%, Ni: 5.72%, Cr: 22.53%, Co: 0.80%, Nb: 0.020%, Ti: 0.020%, Mo: 0.48%, Al: 0.036%, B: 0.0028%, and the rest are Fe and other unavoidable impurities.

[0036] The production method of the steel plate in this embodiment includes steelmaking, continuous casting, hot rolling, and heat treatment processes. The specific production process steps are as follows: (1) Steelmaking process: The qualified molten steel from the primary refining furnace is transferred to the LF furnace for refining. The total refining time in the LF furnace is 65 minutes. The argon blowing is good during the process. The white slag is kept for 35 minutes. After deoxidation, alloys are added in batches to meet the smelting composition requirements. The qualified molten steel from the LF refining is hoisted into the VOD furnace for oxygen blowing and carbon removal to meet the smelting composition requirements, and then vacuum degassing is carried out. The vacuum is maintained for 20 minutes. After the vacuum degassing treatment is completed, soft blowing is carried out for 8 minutes to promote the floating and removal of non-metallic inclusions.

[0037] (2) Continuous casting process: The qualified molten steel is cast into 200mm thick continuous casting billets through a large slab continuous casting machine. During the casting process, the molten steel is superheated by 15°C to ensure that the billet has good internal quality.

[0038] (3) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a maximum heating temperature of 1230°C, a holding stage temperature of 1190°C, a total heating time of 320 min, a starting rolling temperature of 1130°C, a reduction rate of 11% per pass, a final rolling temperature of 880°C, and air cooling to room temperature after rolling.

[0039] (4) Heat treatment process: solution quenching temperature is 900°C, total heating time is 150 min, after being taken out of the furnace, it is quickly water-cooled to 300°C, and then air-cooled to room temperature to obtain the steel plate.

[0040] The steel plate of this embodiment has a yield strength of 322 MPa throughout the entire plate thickness, a tensile strength of 563 MPa, a pitting resistance equivalent PREN≥40, good corrosion resistance, and excellent overall performance. Example 3

[0041] The thickness specification of the steel plate in this embodiment is 20 mm, and its chemical composition and its weight percentage are C: 0.04%, Si: 0.38%, Mn: 0.37%, P: 0.012%, S: 0.003%, Ni: 6.83%, Cr: 20.00%, Co: 0.82%, Nb: 0.050%, Ti: 0.032%, Mo: 0.55%, Al: 0.023%, B: 0.0030%, and the rest are Fe and other unavoidable impurities.

[0042] The production method of the steel plate in this embodiment includes steelmaking, continuous casting, hot rolling, and heat treatment processes. The specific production process steps are as follows: (1) Steelmaking process: The qualified molten steel from the primary refining furnace is transferred to the LF furnace for refining. The total refining time in the LF furnace is 60 minutes. The argon blowing is good during the process. The white slag is kept for 30 minutes. After deoxidation, alloys are added in batches to meet the smelting composition requirements. The qualified molten steel from the LF refining is hoisted into the VOD furnace for oxygen blowing and carbon removal to meet the smelting composition requirements, and then vacuum degassing is carried out. The vacuum is maintained for 23 minutes. After the vacuum degassing treatment, soft blowing is carried out for 11 minutes to promote the floating and removal of non-metallic inclusions.

[0043] (2) Continuous casting process: The qualified molten steel is cast into 230mm thick continuous casting billets through a large slab continuous casting machine. During the casting process, the molten steel is superheated to 23°C to ensure that the billets have good internal quality.

[0044] (3) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a maximum heating temperature of 1200°C, a holding stage temperature of 1186°C, a total heating time of 350 min, a starting rolling temperature of 1060°C, a reduction rate of 15% per pass, a final rolling temperature of 910°C, and air cooling to room temperature after rolling.

[0045] (4) Heat treatment process: solution quenching temperature is 950°C, total heating time is 80 min, after being taken out of the furnace, it is quickly water-cooled to 295°C, and then air-cooled to room temperature to obtain the steel plate.

[0046] The steel plate of this embodiment has a yield strength of 330 MPa throughout the entire plate thickness, a tensile strength of 548 MPa, a pitting resistance equivalent PREN≥42, good corrosion resistance, and excellent overall performance. Example 4

[0047] The thickness specification of the steel plate in this embodiment is 35 mm, and its chemical composition and its weight percentage are C: 0.03%, Si: 0.29%, Mn: 0.20%, P: 0.014%, S: 0.002%, Ni: 5.00%, Cr: 23.45%, Co: 0.96%, Nb: 0.032%, Ti: 0.050%, Mo: 0.020%, Al: 0.028%, B: 0.0018%, and the rest are Fe and other unavoidable impurities.

[0048] The production method of the steel plate in this embodiment includes steelmaking, continuous casting, hot rolling, and heat treatment processes. The specific production process steps are as follows: (1) Steelmaking process: The qualified molten steel from the primary refining furnace is transferred to the LF furnace for refining. The total refining time during the LF furnace refining process is 71 minutes. The argon blowing process is good, the white slag is kept for 32 minutes, and the alloy is added in batches after deoxidation to meet the smelting composition requirements. The qualified molten steel from the LF refining is hoisted into the VOD furnace for oxygen blowing and carbon removal to meet the smelting composition requirements, and then vacuum degassing treatment is carried out. The vacuum is kept for 22 minutes. After the vacuum degassing treatment, soft blowing is carried out for 12 minutes to promote the floating and removal of non-metallic inclusions.

[0049] (2) Continuous casting process: The qualified molten steel is cast into 220mm thick continuous casting billets through a large slab continuous casting machine. During the casting process, the molten steel is superheated to 19°C to ensure that the billets have good internal quality.

[0050] (3) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a maximum heating temperature of 1230°C, a holding stage temperature of 1196°C, a total heating time of 360 min, a starting rolling temperature of 1070°C, a reduction rate of 10% per pass, a final rolling temperature of 890°C, and air cooling to room temperature after rolling.

[0051] (4) Heat treatment process: solution quenching temperature is 930°C, total heating time is 110 min, after being taken out of the furnace, it is quickly water-cooled to 280°C, and then air-cooled to room temperature to obtain the steel plate.

[0052] The steel plate of this embodiment has a yield strength of 346 MPa throughout the entire plate thickness, a tensile strength of 623 MPa, a pitting resistance equivalent PREN≥45, good corrosion resistance, and excellent overall performance. Example 5

[0053] The thickness specification of the steel plate in this embodiment is 50 mm, and its chemical composition and its weight percentage are C: 0.05%, Si: 0.42%, Mn: 0.45%, P: 0.013%, S: 0.002%, Ni: 6.54%, Cr: 25.00%, Co: 1.00%, Nb: 0.048%, Ti: 0.041%, Mo: 0.034%, Al: 0.050%, B: 0.0010%, and the rest are Fe and other inevitable impurities.

[0054] The production method of the steel plate in this embodiment includes steelmaking, continuous casting, hot rolling, and heat treatment processes. The specific production process steps are as follows: (1) Steelmaking process: The qualified molten steel from the primary refining furnace is transferred to the LF furnace for refining. The total refining time in the LF furnace is 80 minutes. The argon blowing is good during the process. The white slag is kept for 41 minutes. After deoxidation, alloys are added in batches to meet the smelting composition requirements. The qualified molten steel from the LF refining is hoisted into the VOD furnace for oxygen blowing and carbon removal to meet the smelting composition requirements, and then vacuum degassing is carried out. The vacuum is kept for 21 minutes. After the vacuum degassing treatment, soft blowing is carried out for 10 minutes to promote the floating and removal of non-metallic inclusions.

[0055] (2) Continuous casting process: The qualified molten steel is cast into 250mm thick continuous casting billets through a large slab continuous casting machine. During the casting process, the molten steel is superheated to 21°C to ensure that the billets have good internal quality.

[0056] (3) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a maximum heating temperature of 1230°C, a holding stage temperature of 1210°C, a total heating time of 380 min, a starting rolling temperature of 1080°C, a reduction rate of 12% per pass, a final rolling temperature of 920°C, and air cooling to room temperature after rolling.

[0057] (4) Heat treatment process: solution quenching temperature is 920°C, total heating time is 170 min, after being taken out of the furnace, it is quickly water-cooled to 270°C, and then air-cooled to room temperature to obtain the steel plate.

[0058] The steel plate of this embodiment has a yield strength of 318 MPa throughout the entire plate thickness, a tensile strength of 586 MPa, a pitting resistance equivalent PREN≥44, good corrosion resistance, and excellent overall performance. Example 6

[0059] The thickness specification of the steel plate in this embodiment is 25 mm, and its chemical composition and its weight percentage are C: 0.04%, Si: 0.50%, Mn: 0.33%, P: 0.015%, S: 0.001%, Ni: 5.24%, Cr: 21.85%, Co: 0.93%, Nb: 0.037%, Ti: 0.046%, Mo: 0.60%, Al: 0.045%, B: 0.0015%, and the rest are Fe and other unavoidable impurities.

[0060] The production method of the steel plate in this embodiment includes steelmaking, continuous casting, hot rolling, and heat treatment processes. The specific production process steps are as follows: (1) Steelmaking process: The qualified molten steel from the primary refining furnace is transferred to the LF furnace for refining. The total refining time in the LF furnace is 76 minutes. The argon blowing is good during the process. The white slag is kept for 43 minutes. After deoxidation, alloys are added in batches to meet the smelting composition requirements. The qualified molten steel from the LF refining is hoisted into the VOD furnace for oxygen blowing and carbon removal to meet the smelting composition requirements, and then vacuum degassing is carried out. The vacuum is maintained for 25 minutes. After the vacuum degassing treatment is completed, soft blowing is carried out for 9 minutes to promote the floating and removal of non-metallic inclusions.

[0061] (2) Continuous casting process: The qualified molten steel is cast into a 210 mm thick continuous casting billet through a large slab continuous casting machine. During the casting process, the molten steel is superheated to 18°C ​​to ensure that the billet has good internal quality.

[0062] (3) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a maximum heating temperature of 1230°C, a holding stage temperature of 1205°C, a total heating time of 320 min, a starting rolling temperature of 1150°C, a reduction rate of 14% per pass, a final rolling temperature of 930°C, and air cooling to room temperature after rolling.

[0063] (4) Heat treatment process: solution quenching temperature is 910°C, total heating time is 80 min, after being taken out of the furnace, it is quickly water-cooled to 240°C, and then air-cooled to room temperature to obtain the steel plate.

[0064] The steel plate of this embodiment has a yield strength of 336 MPa throughout the entire plate thickness, a tensile strength of 593 MPa, a pitting resistance equivalent PREN≥46, good corrosion resistance, and excellent overall performance.

[0065] Comparative Example 1 The technical features that distinguish this comparative example from the embodiment are: C: 0.08%, and the rest are the same as embodiment 1. The steel plate of this embodiment has a yield strength of 390 MPa throughout the entire thickness, a tensile strength of 692 MPa, and a pitting resistance equivalent of PREN38.

[0066] Comparative Example 2 The technical features that distinguish this comparative example from the embodiment are as follows: Si: 0.90%, and the rest are the same as embodiment 1. The steel plate of this embodiment has a yield strength of 365 MPa throughout the entire plate thickness, a tensile strength of 716 MPa, and a pitting corrosion resistance equivalent of PREN36.

[0067] Comparative Example 3 The technical features that distinguish this comparative example from the embodiment are: Mn: 0.70%, and the rest are the same as embodiment 1. The steel plate of this embodiment has a yield strength of 354 MPa throughout the entire thickness, a tensile strength of 687 MPa, and a pitting corrosion resistance equivalent of PREN34.

[0068] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A low-nickel, low-cost chromium-based stainless steel plate, characterized in that: The chemical composition of the steel plate and its weight percentage are: C: 0.02~0.05%, Si: 0.20~0.50%, Mn: 0.20~0.50%, P≤0.015%, S≤0.003%, Ni: 5.00~7.00%, Cr: 20.00~25.00%, Co: 0.80~1.00%, Nb: 0.020~0.050%, Ti: 0.020~0.050%, Mo: 0.20~0.60%, Al: 0.020~0.050%, B: 0.0010~0.0030%, and the rest are Fe and other inevitable impurities.

2. The low-nickel, low-cost chromium-based stainless steel plate according to claim 1, characterized in that: The steel plate has a thickness specification of 20 to 50 mm.

3. The low-nickel, low-cost chromium-based stainless steel plate according to claim 1, characterized in that: The steel plate has a yield strength of ≥300 MPa, a tensile strength of ≥520 MPa, and a pitting resistance equivalent PREN of ≥40.

4. A method for producing a low-nickel, low-cost chromium-based stainless steel plate according to any one of claims 1 to 3, comprising steelmaking, continuous casting, hot rolling and heat treatment processes.

5. The method for producing a low-nickel, low-cost chromium-based stainless steel plate according to claim 4, characterized in that: In the steelmaking process, the qualified molten steel smelted in the primary refining furnace is transferred to the LF furnace for refining, the refining time in the LF furnace refining process is ≥60min, ensuring that argon blowing is good throughout the whole process, the white slag is maintained for ≥30min, and alloys are added in batches after deoxidation is completed to the range of smelting composition requirements; the qualified molten steel refined in the LF is hoisted into the VOD furnace for oxygen blowing and carbon removal to the smelting composition requirements, and then vacuum degassing treatment is carried out, the vacuum maintenance time is ≥20min, and soft blowing is carried out for 8-12min after the vacuum degassing treatment is completed.

6. The method for producing a low-nickel, low-cost chromium-based stainless steel plate according to claim 4, characterized in that: In the continuous casting process, the qualified molten steel is cast into a wide and thick slab with a thickness of 200 to 250 mm, and the superheat is controlled within the range of 15 to 25° C. during the casting process.

7. The method for producing a low-nickel, low-cost chromium-based stainless steel plate according to claim 4, characterized in that: In the heating rolling process, the slab is heated in a continuous furnace, the highest heating temperature is 1230°C, the temperature in the insulation stage is 1180-1210°C, the total heating time is ≥15min / cm, the starting rolling temperature is 1060-1150°C during rolling, the reduction rate of each pass is 10-15%, the final rolling temperature is 880-950°C, and it is air-cooled to room temperature after rolling.

8. The method for producing a low-nickel, low-cost chromium-based stainless steel plate according to claim 4, characterized in that: The heat treatment process has a solution quenching temperature of 900-950°C and a total heating time of 3.0-4.0 min / mm. After being taken out of the furnace, the steel plate is quickly water-cooled to ≤300°C and then air-cooled to room temperature to obtain the steel plate.