WO2021026973A1 - 一种贝氏体不锈钢及其制备方法 - Google Patents

一种贝氏体不锈钢及其制备方法 Download PDF

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WO2021026973A1
WO2021026973A1 PCT/CN2019/103778 CN2019103778W WO2021026973A1 WO 2021026973 A1 WO2021026973 A1 WO 2021026973A1 CN 2019103778 W CN2019103778 W CN 2019103778W WO 2021026973 A1 WO2021026973 A1 WO 2021026973A1
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stainless steel
rolling
stage
furnace
bainitic
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PCT/CN2019/103778
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English (en)
French (fr)
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王平
赵永璞
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王平
赵永璞
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite

Definitions

  • the invention relates to the technical field of stainless steel in iron and steel metallurgy, in particular to a bainite stainless steel and a preparation method thereof.
  • the current stainless steel varieties include austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, sorbitic stainless steel, precipitation hardening stainless steel, and duplex stainless steel.
  • austenitic stainless steel and ferritic stainless steel have low strength
  • martensitic stainless steel has poor toughness
  • duplex stainless steel has high cost
  • precipitation hardening stainless steel is complicated to process
  • sorbitic stainless steel has demanding heat treatment processes.
  • duplex stainless steel and sorbitic stainless steel can be used as structural steel, they still need to be improved and improved.
  • the invention prepares a new type of stainless steel-bainite stainless steel through composition control, improvement of smelting process, especially refining process, and two-stage controlled rolling and controlled cold rolling process.
  • This kind of stainless steel has the comprehensive characteristics of high strength, high toughness, good low temperature impact resistance, simple process, easy processing, and good weldability. It is suitable for the use of various engineering structures and can meet the requirements of longevity, seismic resistance, and wide corrosion resistance. Spectral selectivity requirements, and requirements for inland and marine environmental engineering construction.
  • the invention provides a bainite stainless steel and a preparation method thereof.
  • Bainitic stainless steel is a new type of stainless steel that has the characteristics of high strength, high toughness, impact resistance, earthquake resistance, long life, atmospheric and seawater corrosion, low cost, easy welding, and simple process used as engineering structures. It overcomes the problem of low toughness of traditional martensitic stainless steel, overcomes the complexity of the heat treatment process of traditional stainless steels such as duplex stainless steel and sorbitic stainless steel, and overcomes the strength of ferritic stainless steel and austenitic stainless steel as structural steel Low problem.
  • the present invention provides a bainitic stainless steel.
  • the basic components of the bainitic stainless steel are calculated by mass percentage: C 0.03-0.10%, Cr 10-25%, Mn ⁇ 0.8%, Si ⁇ 0.8%, Ni 1- 2%, P ⁇ 0.03%, S ⁇ 0.020%, Al ⁇ 0.02%, total O ⁇ 30ppm, the rest is Fe and inevitable impurities.
  • the bainitic stainless steel is mainly suitable for chloride ion and atmospheric corrosion environment.
  • the content of Cr can be mainly adjusted according to the requirements of corrosion conditions, and other functional elements such as Cu, Mo, Ne, Ti, V, Al can be adjusted appropriately.
  • Such alloy elements can improve the performance of the stainless steel in different fields and realize an alloy design more suitable for the use environment.
  • the metallographic structure of the bainite stainless steel in use is bainite, with an average crystal grain size of 2-8 microns; the bainite stainless steel has a high yield strength above 400MPa-700MPa and a high yield strength greater than 18%
  • the elongation and impact energy greater than 40J are easy to weld and suitable for engineering structural purposes.
  • a method for preparing bainite stainless steel the specific steps are as follows:
  • the molten steel enters the LF furnace for reduction refining, and the reduction refining synthetic slag needs to be added to the LF furnace for deoxidation, desulfurization and precise control of the composition.
  • the amount of the reduction refining synthetic slag is based on the thickness of the slag layer of 200-300mm or the quality of the molten steel Add 3-5% percentage to LF furnace;
  • the LF furnace starts to maintain the white slag after 10 minutes of argon blowing and stirring; when the slag is too thin, add high calcium ratio limestone to adjust the slag; keep the LF furnace refining and adjusting the composition for no more than 40 minutes;
  • the inclusions can be denatured by using alkali metal cored wire;
  • the refined bainitic stainless steel meets the requirements of the basic composition range of the bainitic stainless steel
  • the bainite stainless steel blank is made by continuous casting machine
  • the first-stage rolling controlled rolling and controlled cooling process is: first heat the bainite stainless steel billet after cold inspection and grinding to 1160-1220°C, and then ensure that the first-stage open-rolling temperature is 1070-1110°C and proceed In the first stage of rolling, the final rolling temperature of the first stage is 1010-1030°C, and the reduction of the bainite stainless steel billet rolled in the first stage is 50-80%;
  • the second-stage rolling controlled rolling and controlled cooling process is: ensuring that the second-stage start-rolling temperature is 930-960°C and performing the second-stage rolling, the second-stage final rolling temperature is 770-820°C, and the final cooling temperature is less than 300°C;
  • the total reduction of the bainite stainless steel blank rolled in the first stage and the reduction of the bainitic stainless steel blank rolled in the second stage is 100%.
  • the lower limit adjustment target of Cr is completed in the AOD furnace, induction furnace, electric arc furnace, etc., and the lower limit target of the composition of the main alloying elements C, Cr, Ni, Mn, and Si is completed.
  • the reduction and refining synthetic slag component CaO in S2 is 50-60%, wherein the total content of CaO in high-quality CaCO 3 is >50%, SiO 2 is 25-30%, CaF 2 is 8-10%, and the rest is high-aluminum refractory Brick-like materials; the reduction and refining synthetic slag in S2 should control the alkalinity CaO/SiO 2 within the range of 2-3; the reduction and refining synthetic slag has a lumpiness less than 20mm, and there must be no powdery materials, and it is sealed in moisture-proof bags. .
  • the alkali metal cored wire in S5 is a metal cored wire containing at least one of calcium and magnesium.
  • the Cr content is mainly adjusted according to the requirements of the corrosion conditions, and other functional elements are appropriately adjusted, such as: Cu, Mo, Ne, Ti, V, Al and other alloy elements to coordinately adapt to high strength, high toughness, and atmospheric resistance And seawater corrosion alloy design requirements.
  • the temperature control in S9 includes laminar cooling or water spray cooling or water spray cooling plus electric heating.
  • the present invention proposes that through composition control, improvement of smelting process, especially refining process, and two-stage controlled rolling and controlled cold rolling process, a stainless steel variety that does not currently exist-bainitic stainless steel is prepared.
  • This stainless steel has strength High, high toughness, good low-temperature impact resistance, easy processing, and good weldability. It is suitable for the use of various engineering structures, and can meet the requirements of engineering longevity, seismic resistance, corrosion resistance and broad-spectrum selectivity, and inland And the requirements of marine environmental engineering construction.
  • the technical problem to be solved by the present invention is to overcome various shortcomings of stainless steel varieties, and invent a new type of stainless steel, namely bainitic stainless steel, which has high strength, high toughness, impact resistance, earthquake resistance, long life and durability as an engineering structure. Low cost, easy welding, simple process and other characteristics of atmospheric and seawater corrosion.
  • the present invention provides a bainitic stainless steel, the basic components of the bainitic stainless steel are calculated by mass percentage: C 0.03-0.10%, Cr 10-25%, Mn ⁇ 0.8%, Si ⁇ 0.8%, Ni 1-2%, P ⁇ 0.03%, S ⁇ 0.020%, Al ⁇ 0.02%, all O ⁇ 30ppm, the rest is Fe and unavoidable impurities.
  • the bainitic stainless steel is mainly suitable for chloride ion and atmospheric corrosion environment.
  • the content of Cr can be adjusted according to the requirements of corrosion conditions and other functional elements such as Cu, Mo, Ne, Ti, V, Al, etc. Alloying elements improve the performance of the stainless steel in different fields and realize an alloy design that is more suitable for the use environment.
  • the metallographic structure of the bainite stainless steel in use is bainite, with an average grain size of 2-8 microns; the bainite stainless steel has a high yield strength above 400MPa-700MPa level and an elongation greater than 18% Rate, and impact energy greater than 40J, easy to weld, suitable for engineering structural purposes.
  • a method for preparing bainite stainless steel the specific steps are as follows:
  • the molten steel enters the LF furnace for reduction refining, and the reduction refining synthetic slag needs to be added to the LF furnace for deoxidation, desulfurization and precise control of the composition.
  • the amount of the reduction refining synthetic slag is based on the thickness of the slag layer of 200-300mm or the quality of the molten steel Add 3-5% percentage to LF furnace;
  • the LF furnace starts to maintain the white slag after 10 minutes of argon blowing and stirring; when the slag is too thin, add high calcium ratio limestone to adjust the slag; keep the LF furnace refining and adjusting the composition for no more than 40 minutes;
  • the inclusions can be denatured by using alkali metal cored wire;
  • the refined bainitic stainless steel meets the requirements of the basic composition range of the bainitic stainless steel
  • the bainite stainless steel blank is made by continuous casting machine
  • the first-stage rolling controlled rolling and controlled cooling process is: first heat the bainite stainless steel billet after cold inspection and grinding to 1160-1220°C, and then ensure that the first-stage open-rolling temperature is 1070-1110°C and proceed In the first stage of rolling, the final rolling temperature of the first stage is 1010-1030°C, and the reduction of the bainite stainless steel billet rolled in the first stage is 50-80%;
  • the second-stage rolling controlled rolling and controlled cooling process is: ensuring that the second-stage start-rolling temperature is 930-960°C and performing the second-stage rolling, the second-stage final rolling temperature is 770-820°C, and the final cooling temperature is less than 300°C;
  • the total reduction of the bainite stainless steel blank rolled in the first stage and the reduction of the bainitic stainless steel blank rolled in the second stage is 100%.
  • S1 completes the lower limit adjustment target of Cr in AOD furnaces, induction furnaces, electric arc furnaces, etc., and completes the lower limit target of the composition of the main alloy elements C, Cr, Ni, Mn, and Si.
  • the reduction and refining synthetic slag component CaO in S2 is 50-60%, and the total content of CaO in high-quality CaCO 3 is >50%, SiO 2 25-30%, CaF 2 8-10%, and the rest high alumina refractory bricks Block material;
  • the reduction and refining synthetic slag in S2 should control the alkalinity CaO/SiO 2 within the range of 2-3;
  • the reduction and refining synthetic slag should have a lumpiness of less than 20mm, and there must be no powdery material, so it can be sealed in moisture-proof bags.
  • the alkali metal cored wire in S5 is a metal cored wire containing at least one of calcium and magnesium.
  • S6 mainly adjusts the Cr content according to the requirements of the corrosion conditions, and appropriately adjusts other functional elements, such as: Cu, Mo, Ne, Ti, V, Al and other alloying elements to coordinately adapt to high strength, high toughness, atmospheric resistance and Alloy design requirements for seawater corrosion.
  • the temperature control in S9 includes laminar cooling or water spray cooling or water spray cooling and electric heating.
  • a method for preparing bainite stainless steel the specific steps are as follows:
  • the molten steel enters the LF furnace for reduction refining, and the reduction refining synthetic slag needs to be added to the LF furnace for deoxidation, desulfurization and precise control of the composition.
  • the amount of the reduction refining synthetic slag is added to the LF furnace according to the mass percentage of the molten steel 5%;
  • Reductive refining synthetic slag is composed of 55% CaO, of which the total content of CaO in high-quality CaCO 3 is >50%, SiO 2 30%, CaF 2 10%, and the remaining high-alumina refractory brick block materials; reduction refining synthetic slag in S2
  • the alkalinity CaO/SiO 2 should be controlled within the range of 2.5; the reduction and refining synthesis slag lumpness is less than 20mm, and there should be no powdery materials;
  • the LF furnace starts to maintain the white slag after 10 minutes of argon blowing and stirring; when the slag is too thin, add high calcium ratio limestone to adjust the slag; keep the LF furnace refining and adjusting the composition for no more than 40 minutes;
  • the inclusions can be denatured by using alkali metal cored wires containing calcium and magnesium;
  • the refined bainitic stainless steel meets the requirements of the basic composition range of the bainitic stainless steel
  • the bainite stainless steel blank is made by continuous casting machine
  • the first-stage rolling controlled rolling and controlled cooling process is: first heating the bainite stainless steel billet after cold inspection and grinding to 1220°C, and then ensuring that the first-stage opening temperature is 1110°C and performing the first-stage rolling
  • the final rolling temperature of the first stage is 1030°C, and the reduction of the bainite stainless steel billet rolled in the first stage is 80%;
  • the second-stage rolling controlled rolling and controlled cooling process is: ensuring that the second-stage start-rolling temperature is 960°C and performing the second-stage rolling, the second-stage final rolling temperature is 820°C, and the final cooling temperature is less than 300°C;
  • the total reduction of the bainite stainless steel blank rolled in the first stage and the reduction of the bainitic stainless steel blank rolled in the second stage is 100%.
  • S6 mainly adjusts the Cr content according to the requirements of the corrosion conditions, and appropriately adjusts other functional elements, such as: Cu, Mo, Ne, Ti, V, Al and other alloying elements to coordinately adapt to high strength, high toughness, atmospheric resistance and Alloy design requirements for seawater corrosion.
  • the bainite stainless steel has a high strength of 700 MPa or more, an elongation of more than 18%, and an impact energy of more than 40J.
  • a method for preparing bainite stainless steel the specific steps are as follows:
  • the reduction refining synthetic slag is added to the LF furnace according to the thickness of the slag layer of 280mm; reduction refining
  • the composition of the synthetic slag is CaO 50%, of which the total content of CaO in high-quality CaCO 3 is >50%, SiO 2 25%, CaF 2 8%, and the remaining high-alumina refractory bricks;
  • the reduction and refining synthetic slag in S2 should be
  • the alkalinity CaO/SiO 2 is controlled within the range of 2; the reduction and refining synthesis slag lumpness is less than 20mm, and there must be no powdery materials;
  • the LF furnace starts to maintain the white slag after 10 minutes of argon blowing and stirring; when the slag is too thin, add high calcium ratio limestone to adjust the slag; keep the LF furnace refining and adjusting the composition for no more than 40 minutes;
  • the inclusions can be denatured by using alkali metal cored wires containing magnesium and calcium;
  • the refined bainitic stainless steel meets the requirements of the basic composition range of the bainitic stainless steel
  • the bainite stainless steel blank is made by continuous casting machine
  • the first-stage rolling controlled rolling and controlled cooling process is: first heating the bainite stainless steel blank after cold inspection and grinding to 1180°C, and then ensuring that the first-stage opening temperature is 1090°C and performing the first-stage rolling
  • the final rolling temperature in the first stage is 1030°C, and the reduction of the bainite stainless steel billet rolled in the first stage is 60%;
  • the second-stage rolling controlled rolling and controlled cooling process is: ensuring that the second-stage start rolling temperature is 950°C and performing the second-stage rolling, the second-stage final rolling temperature is 800°C, and the final cooling temperature is less than 300°C;
  • the total reduction of the bainite stainless steel blank rolled in the first stage and the reduction of the bainitic stainless steel blank rolled in the second stage is 100%.
  • S6 mainly adjusts the Cr content according to the requirements of the corrosion conditions, and appropriately adjusts other functional elements, such as: Cu, Mo, Ne, Ti, V, Al and other alloying elements to coordinately adapt to high strength, high toughness, atmospheric resistance and Alloy design requirements for seawater corrosion.
  • the bainitic stainless steel has a high strength of 500 MPa or more, an elongation of more than 22%, and an impact energy of more than 40J.
  • a method for preparing bainite stainless steel the specific steps are as follows:
  • the molten steel enters the LF furnace for reduction refining, and the reduction refining synthetic slag needs to be added to the LF furnace for deoxidation, desulfurization and precise composition control.
  • the reduction refining synthetic slag is added to the LF furnace according to the mass percentage of the molten steel 3%;
  • Reductive refining synthetic slag is composed of 57% CaO, of which the total content of CaO in high-quality CaCO 3 is >50%, SiO 2 25%, CaF 2 9%, and the remaining high-alumina refractory brick lump materials;
  • reduction refining synthetic slag in S2 The alkalinity CaO/SiO 2 should be controlled within the range of 2.7; the reduction and refining synthesis slag lumpness is less than 20mm, and there should be no powdery materials;
  • the LF furnace starts to maintain the white slag after 10 minutes of argon blowing and stirring; when the slag is too thin, add high calcium ratio limestone to adjust the slag; keep the LF furnace refining and adjusting the composition for no more than 40 minutes;
  • the inclusions can be denatured by using alkali metal cored wires containing calcium and magnesium;
  • the refined bainitic stainless steel meets the requirements of the basic composition range of the bainitic stainless steel
  • the bainite stainless steel blank is made by continuous casting machine
  • the first-stage rolling controlled rolling and controlled cooling process is: first heat the bainite stainless steel billet after cold inspection and grinding to 1190°C, and then ensure that the first-stage opening temperature is 1110°C and perform the first-stage rolling
  • the final rolling temperature of the first stage is 1030°C, and the reduction of the bainite stainless steel billet rolled in the first stage is 70%;
  • the second-stage rolling controlled rolling and controlled cooling process is: ensuring that the second-stage start-rolling temperature is 960°C and performing the second-stage rolling, the second-stage final rolling temperature is 800°C, and the final cooling temperature is less than 300°C;
  • the total reduction of the bainite stainless steel blank rolled in the first stage and the reduction of the bainitic stainless steel blank rolled in the second stage is 100%.
  • S6 mainly adjusts the Cr content according to the requirements of the corrosion conditions, and appropriately adjusts other functional elements, such as: Cu, Mo, Ne, Ti, V, Al and other alloying elements to coordinately adapt to high strength, high toughness, atmospheric resistance and Alloy design requirements for seawater corrosion.
  • the bainite stainless steel has a high strength of 600 MPa or more, an elongation of more than 18%, and an impact energy of more than 40J.
  • a method for preparing bainite stainless steel the specific steps are as follows:
  • the reduction refining synthetic slag is added to the LF furnace according to the thickness of the slag layer of 280mm; reduction refining
  • the composition of the synthetic slag is CaO 50%, of which the total content of CaO in high-quality CaCO 3 is >50%, SiO 2 30%, CaF 2 8%, and the remaining high-alumina refractory bricks;
  • the reduction and refining synthetic slag in S2 should be
  • the alkalinity CaO/SiO 2 is controlled within the range of 2.6; the reduction and refining synthesis slag lumpness is less than 20mm, and there must be no powdery materials;
  • the LF furnace starts to maintain the white slag after 10 minutes of argon blowing and stirring; when the slag is too thin, add high calcium ratio limestone to adjust the slag; keep the LF furnace refining and adjusting the composition for no more than 40 minutes;
  • the inclusions can be denatured by using alkali metal cored wires containing calcium and magnesium;
  • the refined bainitic stainless steel meets the requirements of the basic composition range of the bainitic stainless steel
  • the bainite stainless steel blank is made by continuous casting machine
  • the first-stage rolling controlled rolling and controlled cooling process is: first heat the bainitic stainless steel billet after cold inspection and grinding to 1160°C, and then ensure that the first-stage opening temperature is 1090°C and perform the first-stage rolling
  • the final rolling temperature of the first stage is 1020°C, and the reduction of the bainite stainless steel billet rolled in the first stage is 60%;
  • the second-stage rolling controlled rolling and controlled cooling process is: ensuring that the second-stage start-rolling temperature is 940°C and performing the second-stage rolling, the second-stage final rolling temperature is 780°C, and the final cooling temperature is less than 300°C;
  • the total reduction of the bainite stainless steel blank rolled in the first stage and the reduction of the bainitic stainless steel blank rolled in the second stage is 100%.
  • S6 mainly adjusts the Cr content according to the requirements of the corrosion conditions, and appropriately adjusts other functional elements, such as: Cu, Mo, Ne, Ti, V, Al and other alloying elements to coordinately adapt to high strength, high toughness, atmospheric resistance and Alloy design requirements for seawater corrosion.
  • the bainitic stainless steel has a high strength of 500 MPa or more, an elongation of more than 22%, and an impact energy of more than 40J.
  • the present invention proposes to prepare a stainless steel variety that does not currently exist-bainitic stainless steel through composition control, improvement of smelting process, especially refining process, and two-stage controlled rolling and controlled cold rolling process.
  • This kind of stainless steel has the comprehensive properties of high strength, high toughness, good low temperature impact resistance, easy processing, and good weldability. It is suitable for the use of various engineering structures and can meet the broad-spectrum selectivity requirements for engineering longevity, earthquake resistance, and corrosion resistance. , And requirements for inland and marine environmental engineering construction.

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Abstract

一种贝氏体不锈钢及其制备方法，贝氏体不锈钢的基本成分按质量百分比计为：C 0.03-0.10％，Cr 10-25％，Mn<0.8％，Si<0.8％，Ni 1-2％，P≤0.03％，S<0.020％，Al<0.02％，全O<30ppm，其余为Fe和不可避免的杂质。制备方法采用精炼后、通过连铸机制成贝氏体不锈钢坯料；然后进行包括第一阶段轧制控轧控冷工艺和第二阶段轧制控轧控冷工艺两阶段轧制得到贝氏体不锈钢。贝氏体不锈钢克服了奥氏体不锈钢、铁素体不锈钢强度低，马氏体不锈钢韧性差，双相不锈钢成本高、沉淀硬化不锈钢加工复杂、索氏体不锈钢热处理工艺要求苛刻等问题。

Description

一种贝氏体不锈钢及其制备方法 技术领域
本发明涉及钢铁冶金的不锈钢技术领域，尤其涉及一种贝氏体不锈钢及其制备方法。
背景技术
目前的不锈钢品种有奥氏体不锈钢、铁素体不锈钢、马氏体不锈钢、索氏体不锈钢、沉淀硬化不锈钢、双相不锈钢。其中：奥氏体不锈钢、铁素体不锈钢强度低，马氏体不锈钢韧性差，双相不锈钢成本高、沉淀硬化不锈钢加工复杂、索氏体不锈钢热处理工艺要求苛刻等。双相不锈钢和索氏体不锈钢虽然可以作为结构钢使用，但还需要改进和提高。
本发明通过成分控制、冶炼工艺尤其是精炼工艺的改善、以及两阶段控轧控冷轧制工艺制备出了一种新型的不锈钢品种-贝氏体不锈钢。这种不锈钢具有强度高、韧性高、耐低温冲击性好、工艺简单、易于加工、焊接性好的综合特性，适合各类工程结构的使用，可以满足对工程长寿性、抗震性、耐腐蚀广谱选择性要求、以及内陆及海洋环境工程建设的要求。
发明内容
本发明提供了一种贝氏体不锈钢及其制备方法。贝氏体不锈钢是一种新型的不锈钢品种，具有作为工程结构使用的高强度、高韧性、抗冲击、抗地震、寿命长、耐大气和海水腐蚀的低成本、易焊接、工艺简单等特性，克服了传统马氏体不锈钢的韧性较低的问题，克服了传统不锈钢如双相不锈钢、索氏体不锈钢的热处理过程的复杂性问题，克服了铁素体不锈钢、奥氏体不锈钢作为结 构钢强度低的问题。
本发明提供一种贝氏体不锈钢，所述贝氏体不锈钢的基本成分按质量百分比计为：C 0.03-0.10％，Cr 10-25％，Mn<0.8％，Si<0.8％，Ni 1-2％，P≤0.03％，S<0.020％，Al<0.02％，全O<30ppm，其余为Fe和不可避免的杂质。
优选地，所述贝氏体不锈钢主要适用于氯离子及大气腐蚀环境，可以根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素，如：Cu，Mo，Ne，Ti，V，Al等合金元素，改善该不锈钢在不同领域的使用性能，实现更适应于使用环境的合金设计。
优选地，所述贝氏体不锈钢使用状态的金相组织是贝氏体，晶粒尺寸平均2-8微米；所述贝氏体不锈钢具有400MPa-700MPa级别以上的高屈服强度、大于18％的延伸率、以及大于40J的冲击功，易于焊接，适合于工程结构用途。
一种贝氏体不锈钢的制备方法，具体步骤如下所示：
S1、控制AOD炉、感应炉、电弧炉等进入LF炉的钢水的碳含量、磷含量在最终成分下限以下，防止后期增碳，留出后期操作增C和增P余量；
S2、钢水进入LF炉进行还原精炼，需要向LF炉中加入还原精炼合成渣，以便脱氧、脱硫以及进行成分的精确控制，其中：还原精炼合成渣用量按照渣层厚度200-300mm或钢水的质量百分比3-5％加入LF炉；
S3、LF炉吹氩气搅拌需要见到渣面吹破，LF炉吹氩气后按每吨钢加入0.8kg Al的方式添加铝，此后钢水不再加入铝脱氧；当促进白渣形成时可以在LF炉内的渣表面加入铝粒，但不得采用铝粉替代铝粒，以防止剧烈燃烧；
S4、LF炉吹氩气搅拌10分钟后开始保持白渣；当炉渣过稀时，加入高钙比例石灰石调渣；保持LF炉精炼与调整成分所消耗的时间不大于40分钟；
S5、精炼结束时，可以通过使用碱金属包芯线对夹杂物进行变性处理；
S6、精炼后的贝氏体不锈钢满足所述贝氏体不锈钢的基本成分范围要求；
S7、通过连铸机制成贝氏体不锈钢坯料；
S8、对贝氏体不锈钢坯料进行冷检和修磨；
S9、对冷检和修磨后的贝氏体不锈钢坯料进行包括第一阶段轧制控轧控冷工艺和第二阶段轧制控轧控冷工艺两阶段轧制得到贝氏体不锈钢，所述第一阶段轧制控轧控冷工艺之后需要进行温度控制以满足所述第二阶段轧制控轧控 冷工艺的开轧温度需求，具体两阶段轧制如下所示：
所述第一阶段轧制控轧控冷工艺为：先将冷检和修磨后的贝氏体不锈钢坯料加热到1160-1220℃，然后确保第一阶段开轧温度为1070-1110℃并进行第一阶段轧制，第一阶段终轧温度为1010-1030℃，第一阶段轧制的贝氏体不锈钢坯料压下量为50-80％；
所述第二阶段轧制控轧控冷工艺为：确保第二阶段开轧温度为930-960℃并进行第二阶段轧制，第二阶段终轧温度为770-820℃，终冷温度小于300℃；
所述第一阶段轧制的贝氏体不锈钢坯料压下量与第二阶段轧制的贝氏体不锈钢坯料压下量总和为100％。
优选地，S1中在AOD炉、感应炉、电弧炉等完成Cr的下限调整目标，完成主要合金元素C，Cr，Ni，Mn，Si的成分下限目标。
优选地，S2中的还原精炼合成渣成分CaO 50-60％，其中高品质CaCO 3中CaO含量总量比>50％，SiO 2 25-30％，CaF 2 8-10％，其余高铝耐火砖块状料；S2中的还原精炼合成渣应将碱度CaO/SiO 2控制在2-3的范围内；还原精炼合成渣块度小于20mm，不得有粉状料，以密封防潮袋袋装。
优选地，S5中的碱金属包芯线为含钙、镁中至少一种的金属包芯线。
优选地，S6中根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素，如：Cu，Mo，Ne，Ti，V，Al等合金元素，以协同适应高强度、高韧性、耐大气和海水腐蚀的合金设计需求。
优选地，S9中的温度控制包括层流冷却或喷水冷却或喷水冷却加电加热。
本发明的上述技术方案的有益效果如下：
本发明提出了通过成分控制、冶炼工艺尤其是精炼工艺的改善、以及两阶段控轧控冷轧制工艺制备出了一种目前并不存在的不锈钢品种-贝氏体不锈钢，这种不锈钢具有强度高、韧性高、耐低温冲击性好、易于加工、焊接性好的综合性能，适合各类工程结构的使用，可以满足对工程长寿性、抗震性、耐腐蚀广谱选择性要求、以及内陆及海洋环境工程建设的要求。
具体实施方式
为使本发明要解决的技术问题、技术方案和优点更加清楚，下面将结合具体实施例进行详细描述。
本发明要解决的技术问题是克服不锈钢品种的种种缺点，发明了一种新型的不锈钢即贝氏体不锈钢，具有作为工程结构使用的高强度、高韧性、抗冲击、抗地震、寿命长、耐大气和海水腐蚀的低成本、易焊接、工艺简单等特性。
为解决上述技术问题，本发明提供一种贝氏体不锈钢，所述贝氏体不锈钢的基本成分按质量百分比计为：C 0.03-0.10％，Cr 10-25％，Mn<0.8％，Si<0.8％，Ni 1-2％，P≤0.03％，S<0.020％，Al<0.02％，全O<30ppm，其余为Fe和不可避免的杂质。
其中，所述贝氏体不锈钢主要适用于氯离子及大气腐蚀环境，可以根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素，如：Cu，Mo，Ne，Ti，V，Al等合金元素，改善该不锈钢在不同领域的使用性能，实现更适应于使用环境的合金设计。
其中，所述贝氏体不锈钢使用状态的金相组织是贝氏体，晶粒尺寸平均2-8微米；所述贝氏体不锈钢具有400MPa-700MPa级别以上的高屈服强度、大于18％的延伸率、以及大于40J的冲击功，易于焊接，适合于工程结构用途。
一种贝氏体不锈钢的制备方法，具体步骤如下所示：
S1、控制AOD炉、感应炉、电弧炉等进入LF炉的钢水的碳含量、磷含量在最终成分下限以下，防止后期增碳，留出后期操作增C和增P余量；
S2、钢水进入LF炉进行还原精炼，需要向LF炉中加入还原精炼合成渣，以便脱氧、脱硫以及进行成分的精确控制，其中：还原精炼合成渣用量按照渣层厚度200-300mm或钢水的质量百分比3-5％加入LF炉；
S3、LF炉吹氩气搅拌需要见到渣面吹破，LF炉吹氩气后按每吨钢加入0.8kg Al的方式添加铝，此后钢水不再加入铝脱氧；当促进白渣形成时可以在LF炉内的渣表面加入铝粒，但不得采用铝粉替代铝粒，以防止剧烈燃烧；
S4、LF炉吹氩气搅拌10分钟后开始保持白渣；当炉渣过稀时，加入高钙比例石灰石调渣；保持LF炉精炼与调整成分所消耗的时间不大于40分钟；
S5、精炼结束时，可以通过使用碱金属包芯线对夹杂物进行变性处理；
S6、精炼后的贝氏体不锈钢满足所述贝氏体不锈钢的基本成分范围要求；
S7、通过连铸机制成贝氏体不锈钢坯料；
S8、对贝氏体不锈钢坯料进行冷检和修磨；
S9、对冷检和修磨后的贝氏体不锈钢坯料进行包括第一阶段轧制控轧控冷工艺和第二阶段轧制控轧控冷工艺两阶段轧制得到贝氏体不锈钢，所述第一阶段轧制控轧控冷工艺之后需要进行温度控制以满足所述第二阶段轧制控轧控冷工艺的开轧温度需求，具体两阶段轧制如下所示：
所述第一阶段轧制控轧控冷工艺为：先将冷检和修磨后的贝氏体不锈钢坯料加热到1160-1220℃，然后确保第一阶段开轧温度为1070-1110℃并进行第一阶段轧制，第一阶段终轧温度为1010-1030℃，第一阶段轧制的贝氏体不锈钢坯料压下量为50-80％；
所述第二阶段轧制控轧控冷工艺为：确保第二阶段开轧温度为930-960℃并进行第二阶段轧制，第二阶段终轧温度为770-820℃，终冷温度小于300℃；
所述第一阶段轧制的贝氏体不锈钢坯料压下量与第二阶段轧制的贝氏体不锈钢坯料压下量总和为100％。
其中，S1中在AOD炉、感应炉、电弧炉等完成Cr的下限调整目标，完成主要合金元素C，Cr，Ni，Mn，Si的成分下限目标。
其中，S2中的还原精炼合成渣成分CaO 50-60％，其中高品质CaCO 3中CaO含量总量比>50％，SiO 2 25-30％，CaF 2 8-10％，其余高铝耐火砖块状料；S2中的还原精炼合成渣应将碱度CaO/SiO 2控制在2-3的范围内；还原精炼合成渣块度小于20mm，不得有粉状料，以密封防潮袋袋装。
其中，S5中的碱金属包芯线为含钙、镁中至少一种的金属包芯线。
其中，S6中根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素，如：Cu，Mo，Ne，Ti，V，Al等合金元素，以协同适应高强度、高韧性、耐大气和海水腐蚀的合金设计需求。
其中，S9中的温度控制包括层流冷却或喷水冷却或喷水冷却加电加热。
具体贝氏体不锈钢及其制备方法结合以下实施例进行说明：
实施例一：
一种贝氏体不锈钢，所述贝氏体不锈钢的基本成分按质量百分比计为：C 0.10％，Cr 13％，Mn<0.48％，Si<0.4％，Ni 1.6％，P＝0.03％，S＝0.010％，Al＝0.015％，全O<30ppm，其余为Fe和不可避免的杂质。
一种贝氏体不锈钢的制备方法，具体步骤如下所示：
S1、控制AOD炉进入LF炉的钢水的碳含量、磷含量在最终成分下限以下，防止后期增碳，留出后期操作增C和增P余量；
S2、钢水进入LF炉进行还原精炼，需要向LF炉中加入还原精炼合成渣，以便脱氧、脱硫以及进行成分的精确控制，其中：还原精炼合成渣用量按照钢水的质量百分比5％加入LF炉；还原精炼合成渣成分CaO 55％，其中高品质CaCO 3中CaO含量总量比>50％，SiO 2 30％，CaF 2 10％，其余高铝耐火砖块状料；S2中的还原精炼合成渣应将碱度CaO/SiO 2控制在2.5的范围内；还原精炼合成渣块度小于20mm，不得有粉状料；
S3、LF炉吹氩气搅拌需要见到渣面吹破，LF炉吹氩气后按每吨钢加入0.8kg Al的方式添加铝，此后钢水不再加入铝脱氧；当促进白渣形成时可以在LF炉内的渣表面加入铝粒，但不得采用铝粉替代铝粒，以防止剧烈燃烧；
S4、LF炉吹氩气搅拌10分钟后开始保持白渣；当炉渣过稀时，加入高钙比例石灰石调渣；保持LF炉精炼与调整成分所消耗的时间不大于40分钟；
S5、精炼结束时，可以通过使用碱金属含钙、镁包芯线对夹杂物进行变性处理；
S6、精炼后的贝氏体不锈钢满足所述贝氏体不锈钢的基本成分范围要求；
S7、通过连铸机制成贝氏体不锈钢坯料；
S8、对贝氏体不锈钢坯料进行冷检和修磨；
S9、对冷检和修磨后的贝氏体不锈钢坯料进行包括第一阶段轧制控轧控冷工艺和第二阶段轧制控轧控冷工艺两阶段轧制得到贝氏体不锈钢，所述第一阶段轧制控轧控冷工艺之后需要进行层流冷却以满足所述第二阶段轧制控轧控冷工艺的开轧温度需求，具体两阶段轧制如下所示：
所述第一阶段轧制控轧控冷工艺为：先将冷检和修磨后的贝氏体不锈钢坯料加热到1220℃，然后确保第一阶段开轧温度为1110℃并进行第一阶段轧制，第一阶段终轧温度为1030℃，第一阶段轧制的贝氏体不锈钢坯料压下量为 80％；
所述第二阶段轧制控轧控冷工艺为：确保第二阶段开轧温度为960℃并进行第二阶段轧制，第二阶段终轧温度为820℃，终冷温度小于300℃；
所述第一阶段轧制的贝氏体不锈钢坯料压下量与第二阶段轧制的贝氏体不锈钢坯料压下量总和为100％。
其中，S6中根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素，如：Cu，Mo，Ne，Ti，V，Al等合金元素，以协同适应高强度、高韧性、耐大气和海水腐蚀的合金设计需求。
所述贝氏体不锈钢具有700MPa以上的高强度、大于18％的延伸率、以及大于40J的冲击功。
实施例二：
一种贝氏体不锈钢，所述贝氏体不锈钢的基本成分按质量百分比计为：C 0.03％，Cr 10％，Mn<0.8％，Si<0.45％，Ni 1％，P＝0.025％，S＝0.020％，Al＝0.018％，全O<30ppm，其余为Fe和不可避免的杂质。
一种贝氏体不锈钢的制备方法，具体步骤如下所示：
S1、控制感应炉进入LF炉的钢水的碳含量、磷含量在最终成分下限以下，防止后期增碳，留出后期操作增C和增P余量；
S2、钢水进入LF炉进行还原精炼，需要向LF炉中加入还原精炼合成渣，以便脱氧、脱硫以及进行成分的精确控制，其中：还原精炼合成渣用量按照渣层厚度280mm加入LF炉；还原精炼合成渣成分CaO 50％，其中高品质CaCO 3中CaO含量总量比>50％，SiO 2 25％，CaF 2 8％，其余高铝耐火砖块状料；S2中的还原精炼合成渣应将碱度CaO/SiO 2控制在2的范围内；还原精炼合成渣块度小于20mm，不得有粉状料；
S3、LF炉吹氩气搅拌需要见到渣面吹破，LF炉吹氩气后按每吨钢加入0.8kg Al的方式添加铝，此后钢水不再加入铝脱氧；当促进白渣形成时可以在LF炉内的渣表面加入铝粒，但不得采用铝粉替代铝粒，以防止剧烈燃烧；
S4、LF炉吹氩气搅拌10分钟后开始保持白渣；当炉渣过稀时，加入高钙比例石灰石调渣；保持LF炉精炼与调整成分所消耗的时间不大于40分钟；
S5、精炼结束时，可以通过使用碱金属含镁、钙包芯线对夹杂物进行变性处理；
S6、精炼后的贝氏体不锈钢满足所述贝氏体不锈钢的基本成分范围要求；
S7、通过连铸机制成贝氏体不锈钢坯料；
S8、对贝氏体不锈钢坯料进行冷检和修磨；
S9、对冷检和修磨后的贝氏体不锈钢坯料进行包括第一阶段轧制控轧控冷工艺和第二阶段轧制控轧控冷工艺两阶段轧制得到贝氏体不锈钢，所述第一阶段轧制控轧控冷工艺之后需要进行喷水冷却以满足所述第二阶段轧制控轧控冷工艺的开轧温度需求，具体两阶段轧制如下所示：
所述第一阶段轧制控轧控冷工艺为：先将冷检和修磨后的贝氏体不锈钢坯料加热到1180℃，然后确保第一阶段开轧温度为1090℃并进行第一阶段轧制，第一阶段终轧温度为1030℃，第一阶段轧制的贝氏体不锈钢坯料压下量为60％；
所述第二阶段轧制控轧控冷工艺为：确保第二阶段开轧温度为950℃并进行第二阶段轧制，第二阶段终轧温度为800℃，终冷温度小于300℃；
所述第一阶段轧制的贝氏体不锈钢坯料压下量与第二阶段轧制的贝氏体不锈钢坯料压下量总和为100％。
其中，S6中根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素，如：Cu，Mo，Ne，Ti，V，Al等合金元素，以协同适应高强度、高韧性、耐大气和海水腐蚀的合金设计需求。
所述贝氏体不锈钢具有500MPa以上的高强度、大于22％的延伸率、以及大于40J的冲击功。
实施例三：
一种贝氏体不锈钢，所述贝氏体不锈钢的基本成分按质量百分比计为：C 0.06％，Cr 16％，Mn<0.4％，Si<0.4％，Ni 1.8％，P＝0.03％，S＝0.015％，Al＝0.014％，全O<30ppm，其余为Fe和不可避免的杂质。
一种贝氏体不锈钢的制备方法，具体步骤如下所示：
S1、控制AOD炉进入LF炉的钢水的碳含量、磷含量在最终成分下限以 下，防止后期增碳，留出后期操作增C和增P余量；
S2、钢水进入LF炉进行还原精炼，需要向LF炉中加入还原精炼合成渣，以便脱氧、脱硫以及进行成分的精确控制，其中：还原精炼合成渣用量按照钢水的质量百分比3％加入LF炉；还原精炼合成渣成分CaO 57％，其中高品质CaCO 3中CaO含量总量比>50％，SiO 2 25％，CaF 2 9％，其余高铝耐火砖块状料；S2中的还原精炼合成渣应将碱度CaO/SiO 2控制在2.7的范围内；还原精炼合成渣块度小于20mm，不得有粉状料；
S3、LF炉吹氩气搅拌需要见到渣面吹破，LF炉吹氩气后按每吨钢加入0.8kg Al的方式添加铝，此后钢水不再加入铝脱氧；当促进白渣形成时可以在LF炉内的渣表面加入铝粒，但不得采用铝粉替代铝粒，以防止剧烈燃烧；
S4、LF炉吹氩气搅拌10分钟后开始保持白渣；当炉渣过稀时，加入高钙比例石灰石调渣；保持LF炉精炼与调整成分所消耗的时间不大于40分钟；
S5、精炼结束时，可以通过使用碱金属含钙、镁包芯线对夹杂物进行变性处理；
S6、精炼后的贝氏体不锈钢满足所述贝氏体不锈钢的基本成分范围要求；
S7、通过连铸机制成贝氏体不锈钢坯料；
S8、对贝氏体不锈钢坯料进行冷检和修磨；
S9、对冷检和修磨后的贝氏体不锈钢坯料进行包括第一阶段轧制控轧控冷工艺和第二阶段轧制控轧控冷工艺两阶段轧制得到贝氏体不锈钢，所述第一阶段轧制控轧控冷工艺之后需要进行喷水冷却加电加热以满足所述第二阶段轧制控轧控冷工艺的开轧温度需求，具体两阶段轧制如下所示：
所述第一阶段轧制控轧控冷工艺为：先将冷检和修磨后的贝氏体不锈钢坯料加热到1190℃，然后确保第一阶段开轧温度为1110℃并进行第一阶段轧制，第一阶段终轧温度为1030℃，第一阶段轧制的贝氏体不锈钢坯料压下量为70％；
所述第二阶段轧制控轧控冷工艺为：确保第二阶段开轧温度为960℃并进行第二阶段轧制，第二阶段终轧温度为800℃，终冷温度小于300℃；
所述第一阶段轧制的贝氏体不锈钢坯料压下量与第二阶段轧制的贝氏体不锈钢坯料压下量总和为100％。
其中，S6中根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素，如：Cu，Mo，Ne，Ti，V，Al等合金元素，以协同适应高强度、高韧性、耐大气和海水腐蚀的合金设计需求。
所述贝氏体不锈钢具有600MPa以上的高强度、大于18％的延伸率、以及大于40J的冲击功。
实施例四：
一种贝氏体不锈钢，所述贝氏体不锈钢的基本成分按质量百分比计为：C 0.08％，Cr 22％，Mn<0.42％，Si<0.8％，Ni 1.2％，P＝0.022％，S＝0.015％，Al＝0.013％，全O<30ppm，其余为Fe和不可避免的杂质。
一种贝氏体不锈钢的制备方法，具体步骤如下所示：
S1、控制电弧炉进入LF炉的钢水的碳含量、磷含量在最终成分下限以下，防止后期增碳，留出后期操作增C和增P余量；
S2、钢水进入LF炉进行还原精炼，需要向LF炉中加入还原精炼合成渣，以便脱氧、脱硫以及进行成分的精确控制，其中：还原精炼合成渣用量按照渣层厚度280mm加入LF炉；还原精炼合成渣成分CaO 50％，其中高品质CaCO 3中CaO含量总量比>50％，SiO 2 30％，CaF 2 8％，其余高铝耐火砖块状料；S2中的还原精炼合成渣应将碱度CaO/SiO 2控制在2.6的范围内；还原精炼合成渣块度小于20mm，不得有粉状料；
S3、LF炉吹氩气搅拌需要见到渣面吹破，LF炉吹氩气后按每吨钢加入0.8kg Al的方式添加铝，此后钢水不再加入铝脱氧；当促进白渣形成时可以在LF炉内的渣表面加入铝粒，但不得采用铝粉替代铝粒，以防止剧烈燃烧；
S4、LF炉吹氩气搅拌10分钟后开始保持白渣；当炉渣过稀时，加入高钙比例石灰石调渣；保持LF炉精炼与调整成分所消耗的时间不大于40分钟；
S5、精炼结束时，可以通过使用碱金属含钙、镁包芯线对夹杂物进行变性处理；
S6、精炼后的贝氏体不锈钢满足所述贝氏体不锈钢的基本成分范围要求；
S7、通过连铸机制成贝氏体不锈钢坯料；
S8、对贝氏体不锈钢坯料进行冷检和修磨；
S9、对冷检和修磨后的贝氏体不锈钢坯料进行包括第一阶段轧制控轧控冷工艺和第二阶段轧制控轧控冷工艺两阶段轧制得到贝氏体不锈钢，所述第一阶段轧制控轧控冷工艺之后需要进行层流冷却以满足所述第二阶段轧制控轧控冷工艺的开轧温度需求，具体两阶段轧制如下所示：
所述第一阶段轧制控轧控冷工艺为：先将冷检和修磨后的贝氏体不锈钢坯料加热到1160℃，然后确保第一阶段开轧温度为1090℃并进行第一阶段轧制，第一阶段终轧温度为1020℃，第一阶段轧制的贝氏体不锈钢坯料压下量为60％；
所述第二阶段轧制控轧控冷工艺为：确保第二阶段开轧温度为940℃并进行第二阶段轧制，第二阶段终轧温度为780℃，终冷温度小于300℃；
所述第一阶段轧制的贝氏体不锈钢坯料压下量与第二阶段轧制的贝氏体不锈钢坯料压下量总和为100％。
其中，S6中根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素，如：Cu，Mo，Ne，Ti，V，Al等合金元素，以协同适应高强度、高韧性、耐大气和海水腐蚀的合金设计需求。
所述贝氏体不锈钢具有500MPa以上的高强度、大于22％的延伸率、以及大于40J的冲击功。
综上可见，本发明提出了通过成分控制、冶炼工艺尤其是精炼工艺的改善、以及两阶段控轧控冷轧制工艺制备出了一种目前并不存在的不锈钢品种-贝氏体不锈钢，这种不锈钢具有强度高、韧性高、耐低温冲击性好、易于加工、焊接性好的综合性能，适合各类工程结构的使用，可以满足对工程长寿性、抗震性、耐腐蚀广谱选择性要求、以及内陆及海洋环境工程建设的要求。
以上所述是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明所述原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。

Claims (9)

  1. 一种贝氏体不锈钢，其特征在于，所述贝氏体不锈钢的基本成分按质量百分比计为：C 0.03-0.10％，Cr 10-25％，Mn<0.8％，Si<0.8％，Ni 1-2％，P≤0.03％，S<0.020％，Al<0.02％，全O<30ppm，其余为Fe和不可避免的杂质。
  2. 根据权利要求1所述贝氏体不锈钢，其特征在于，所述贝氏体不锈钢基本成分中还可以添加Cu，Mo，Ne，Ti，V合金元素中的至少一种。
  3. 根据权利要求1所述贝氏体不锈钢的新型不锈钢，其特征在于，所述贝氏体不锈钢使用状态的金相组织是贝氏体，晶粒尺寸平均2-8微米；所述贝氏体不锈钢具有400MPa-700MPa级别以上的高屈服强度、大于18％的延伸率、以及大于40J的冲击功。
  4. 一种根据权利要求1所述贝氏体不锈钢的制备方法，其特征在于，具体步骤如下所示：
    S1、控制AOD炉或感应炉或电弧炉进入LF炉的钢水的碳含量、磷含量在最终成分下限以下，防止后期增碳，留出后期操作增C和增P余量；
    S2、钢水进入LF炉进行还原精炼，需要向LF炉中加入还原精炼合成渣，以便脱氧、脱硫以及进行成分的精确控制，其中：还原精炼合成渣用量按照渣层厚度200-300mm或钢水的质量百分比3-5％加入LF炉；
    S3、LF炉吹氩气搅拌需要见到渣面吹破，LF炉吹氩气后按每吨钢加入0.8kg Al的方式添加铝，此后钢水不再加入铝脱氧；当促进白渣形成时可以在LF炉内的渣表面加入铝粒，但不得采用铝粉替代铝粒，以防止剧烈燃烧；
    S4、LF炉吹氩气搅拌10分钟后开始保持白渣；当炉渣过稀时，加入高钙比例石灰石调渣；保持LF炉精炼与调整成分所消耗的时间不大于40分钟；
    S5、精炼结束时，可以通过使用碱金属包芯线对夹杂物进行变性处理；
    S6、精炼后的贝氏体不锈钢满足所述贝氏体不锈钢的基本成分范围要求；
    S7、通过连铸机制成贝氏体不锈钢坯料；
    S8、对贝氏体不锈钢坯料进行冷检和修磨；
    S9、对冷检和修磨后的贝氏体不锈钢坯料进行包括第一阶段轧制控轧控冷工艺和第二阶段轧制控轧控冷工艺两阶段轧制得到贝氏体不锈钢，所述第一阶 段轧制控轧控冷工艺之后需要进行温度控制以满足所述第二阶段轧制控轧控冷工艺的开轧温度需求，具体两阶段轧制如下所示：
    所述第一阶段轧制控轧控冷工艺为：先将冷检和修磨后的贝氏体不锈钢坯料加热到1160-1220℃，然后确保第一阶段开轧温度为1070-1110℃并进行第一阶段轧制，第一阶段终轧温度为1010-1030℃，第一阶段轧制的贝氏体不锈钢坯料压下量为50-80％；
    所述第二阶段轧制控轧控冷工艺为：确保第二阶段开轧温度为930-960℃并进行第二阶段轧制，第二阶段终轧温度为770-820℃，终冷温度小于300℃；
    所述第一阶段轧制的贝氏体不锈钢坯料压下量与第二阶段轧制的贝氏体不锈钢坯料压下量总和为100％。
  5. 根据权利要求4所述的制备方法，其特征在于，S1中在AOD炉或感应炉或电弧炉完成Cr的下限调整目标，完成主要合金元素C，Cr，Ni，Mn，Si的成分下限目标。
  6. 根据权利要求4所述的制备方法，其特征在于，S2中的还原精炼合成渣成分CaO 50-60％，其中高品质CaCO 3中CaO含量总量比>50％，SiO 225-30％，CaF 28-10％，其余高铝耐火砖块状料；S2中的还原精炼合成渣应将碱度CaO/SiO 2控制在2-3的范围内；还原精炼合成渣块度小于20mm，不得有粉状料，以密封防潮袋袋装。
  7. 根据权利要求4所述的制备方法，其特征在于，S5中的碱金属包芯线为含钙、镁中至少一种的金属包芯线。
  8. 根据权利要求4所述的制备方法，其特征在于，S6中根据腐蚀条件的要求主要调整Cr含量，适当调整其它功能性元素Cu，Mo，Ne，Ti，V，Al。
  9. 根据权利要求4所述的制备方法，其特征在于，S9中的温度控制包括层流冷却或喷水冷却或喷水冷却加电加热。
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CN109487046A (zh) * 2018-12-11 2019-03-19 南阳汉冶特钢有限公司 一种高强度高韧性船板钢eh550厚板及其生产方法

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