阅读说明：本技术 一种海洋用回火索氏体高强韧不锈结构钢及其制备方法 (Marine tempered sorbite high-strength and high-toughness stainless structural steel and preparation method thereof ) 是由 王平 赵永璞 于 2019-10-14 设计创作，主要内容包括：本发明提供一种海洋用回火索氏体高强韧不锈结构钢及其制备方法,属于钢铁冶金领域和建筑结构抗震不锈钢材料的领域。其基本成分按质量百分比计为：C 0.07-0.16wt％,Si 0.4-1.5wt％,Mn≤1.0wt％,Cr 17.0-26.0wt％,Ni 1.5-2.5wt％,Mo≤1.5wt％,Al 0.01-0.05wt％,P≤0.05wt％,S≤0.020wt％,全O≤40ppm,其余为Fe和不可避免的杂质。本发明适合于沿海和海上建筑结构使用的耐沿海气候和一般海水腐蚀、兼有抵抗地震功能的高强韧不锈结构钢,满足高温、高盐、高湿的海洋环境对高耐蚀钢的迫切需求。(The invention provides a high-toughness marine tempered sorbite stainless structural steel and a preparation method thereof, and belongs to the field of ferrous metallurgy and the field of building structure earthquake-resistant stainless steel materials. The base components of the material by mass percent are as follows: 0.07 to 0.16 weight percent of C, 0.4 to 1.5 weight percent of Si, less than or equal to 1.0 weight percent of Mn, 17.0 to 26.0 weight percent of Cr, 1.5 to 2.5 weight percent of Ni, less than or equal to 1.5 weight percent of Mo, 0.01 to 0.05 weight percent of Al, less than or equal to 0.05 weight percent of P, less than or equal to 0.020 weight percent of S, less than or equal to 40ppm of total O, and the balance of Fe and inevitable impurities. The invention is suitable for high-strength and high-toughness stainless structural steel which is used for coastal and offshore building structures, resists coastal climate and general seawater corrosion, has the earthquake resistance function, and meets the urgent requirements of high-temperature, high-salt and high-humidity marine environments on high-corrosion-resistant steel.)

1. The marine tempered sorbite high-strength and high-toughness stainless structural steel is characterized by comprising the following basic components in percentage by mass: 0.07 to 0.16 weight percent of C, 0.4 to 1.5 weight percent of Si, less than or equal to 1.0 weight percent of Mn, 17.0 to 26.0 weight percent of Cr, 1.5 to 2.5 weight percent of Ni, less than or equal to 1.5 weight percent of Mo, 0.01 to 0.05 weight percent of Al, less than or equal to 0.05 weight percent of P, less than or equal to 0.020 weight percent of S, less than or equal to 40ppm of total O, and the balance of Fe and inevitable impurities.

2. the marine tempered sorbite high-toughness stainless structural steel as claimed in claim 1, wherein the metallographic structure of the marine tempered sorbite high-toughness stainless structural steel is formed by uniformly distributing chromium carbides with an average size of 200-450 nm on a ferrite matrix, which are also called tempered sorbites; the average grain size is less than 10 microns.

3. The marine tempered sorbite high-toughness stainless structural steel as claimed in claim 1, wherein the neutral salt spray corrosion resistance of the marine tempered sorbite high-toughness stainless structural steel is superior to or equal to 2205 duplex stainless steel and 316 stainless steel when the chromium content of the marine tempered sorbite high-toughness stainless structural steel is 17-20 wt%, and the marine tempered sorbite high-toughness stainless structural steel is suitable for common coastal environments; chromium content >20 wt% when used in a seawater environment and increases with increasing seawater temperature; the neutral salt spray corrosion resistance of the stainless steel with high chromium content is similar to that of austenitic 316L stainless steel and ferritic 447 stainless steel.

4. The marine tempered sorbite high-toughness stainless structural steel according to claim 1, wherein the marine tempered sorbite high-toughness stainless structural steel is realized by controlling 0.7-1.5 wt% of silicon and 0.6-1.5 wt% of molybdenum and performing controlled rolling, controlled cooling and heat treatment for grain refining aiming at higher pitting corrosion resistance requirements.

5. The marine tempered sorbite high-strength and high-toughness stainless structural steel as claimed in claim 1, wherein the yield strength Rp0.2 of the marine tempered sorbite high-strength and high-toughness stainless structural steel is more than or equal to 500MPa, the breaking strength Rm is more than or equal to 650MPa, the elongation is more than or equal to 18%, the reduction of area is more than or equal to 40%, and the impact absorption energy is more than or equal to 40J; meet the mechanical property required by the building structural steel and have the function of anti-seismic steel.

6. The method for preparing the marine tempered sorbite high-strength and high-toughness stainless structural steel as claimed in claim 1, wherein the preparation method comprises the following steps:

s1, taking the raw material As the surface layer ore of the low-phosphorus laterite-nickel ore, and requiring that heavy metal elements in the ore are As low As possible, so As to ensure that the total content of As, Sn, Pb, Sb and Bi in molten iron of a blast furnace or an electric furnace is not more than 150ppm and the single content is not more than 50 ppm; smelting into molten iron by a blast furnace or an ore-smelting electric furnace, and sending the molten iron to AOD for blowing; or molten iron obtained by smelting low-nickel iron blocks by an induction furnace and an electric arc furnace is sent to AOD for blowing; finishing the adjustment of the lower limit target of the components of main alloy elements C, Cr, Ni, Mn and Si of the marine tempered sorbite high-strength stainless structural steel in the AOD converting process;

S2, transferring the molten steel blown by the AOD in the S1 into an LF furnace, and enabling the carbon content and the phosphorus content of the molten steel entering the LF furnace to be below the final component lower limit, so as to prevent later-stage carburetion and leave the allowance for later-stage operation of C increase and P increase;

S3, adding 200-300 mm-thick reduction refining slag into the LF furnace, and carrying out opposite feedingreducing and refining the molten steel entering the LF furnace so as to facilitate deoxidation and desulfurization and accurate component adjustment; reducing refining slag with CaO/SiO alkalinity₂Controlling the content in the range of 2-3, wherein the components of the reduction refining slag are CaO: 50-60 wt% of high-quality CaCO₃The total content of CaO is more than 50 wt%, and SiO is₂：25-30wt％，CaF₂: 10 wt% of the rest high-aluminum refractory brick block material; the lumpiness of the reduced refining slag is less than 20mm, powder materials cannot exist, and the reduced refining slag needs to be packaged in a sealed moisture-proof bag;

S4, blowing argon gas into the LF for stirring, wherein the argon gas blown into the LF is only required to be stirred to the extent that the slag surface is blown to be broken; then adding aluminum in a manner of adding 0.8-1.2kg of Al into each ton of steel, and in the subsequent process, adding no aluminum into molten steel for deoxidation; aluminum particles can be added to the surface of the LF slag when the formation of white slag is promoted, but aluminum powder cannot be used for replacing the aluminum particles, so that the aluminum powder is prevented from being violently combusted;

s5, blowing argon into the LF furnace, stirring for 10 minutes, then keeping white slag, adding limestone with high calcium proportion to adjust slag when the slag is too thin, so as to keep foamability of the slag, and smoothly refining and adjusting components of the LF furnace; keeping the time consumed by refining and adjusting the LF furnace to be not more than 40 minutes;

S6, after refining, performing denaturation treatment on inclusions in molten steel through an alkali metal cored wire to enable the components of the molten steel to meet the basic components of the marine tempered sorbite high-strength stainless structural steel;

The molten steel obtained after refining in S7 and S6 is sent to a continuous casting machine to be cast into a plate blank, a square blank or a rectangular blank;

S8, cooling the plate blank or the square blank or the rectangular blank, then checking and grinding the plate blank or the square blank or the rectangular blank, and then carrying out controlled rolling and controlled cooling rolling process and heat treatment in a rolling mill to obtain the required marine tempered sorbite high-strength and high-toughness stainless structural steel.

7. the method for preparing high-toughness stainless structural steel of oceanic tempered sorbite as claimed in claim 6, wherein in the rolling process and heat treatment of controlled rolling and controlled cooling of S8, for the steel with Si content lower than 0.7 wt% and Mo content lower than 0.6 wt%, the steel needs to be immediately cooled to 680-720 ℃ after finishing the finish rolling at 940 ℃ by spraying, and isothermal treatment is carried out for 2.5-5 hours.

8. The method for preparing the high-toughness stainless structural steel of the marine tempered sorbite as claimed in claim 6, wherein in the rolling process and the heat treatment of the controlled rolling and the controlled cooling of S8, for the steel with Si content more than or equal to 0.7 wt% and Mo content 0.6-1.5 wt%, after the finish rolling at 940 ℃, the temperature is raised to 1020 ℃ -1050 ℃, the heat is preserved for 1-1.5 hours, and then the steel is immediately sprayed and cooled to 680-720 ℃ for isothermal treatment for 2.5-5 hours.

9. The method for preparing the marine tempered sorbite high-strength and high-toughness stainless structural steel as claimed in claim 6, wherein in the rolling process and the heat treatment of controlled rolling and controlled cooling of S8, for medium and heavy plates and other large-size steel materials and steel materials with higher mechanical property requirements, the steel materials are immediately cut to length and then are cooled to room temperature by spraying; then heating to 1040-1140 deg.C, and heat-insulating for 1-1.5 hr; then quenching water and cooling to room temperature; then the temperature is increased to 680 ℃ and 740 ℃, and the temperature is preserved for 3 to 5 hours; then, the mixture is quenched again to 200 ℃ or lower.

10. the method for preparing the marine tempered sorbite high-strength and high-toughness stainless structural steel as claimed in claim 6, wherein the refining in the preparation method enables the contents of impurities and oxygen and sulfur in the steel to reach a high purity level, the total oxygen content is less than 40ppm, S is less than or equal to 0.020 wt%, and P is less than or equal to 0.05 wt%; according to the ASTM-E45 inclusion test standard, the grades of various inclusions such as medium plates, bars and the like are all below 1.5 grade.

Technical Field

the invention belongs to the field of ferrous metallurgy and the field of building structure anti-seismic stainless steel materials, and relates to a marine tempered sorbite high-strength and high-toughness stainless structural steel which is suitable for marine engineering structures and has marine climate resistance and general seawater corrosion resistance, and a preparation method thereof.

Background

Along with social development, mankind builds more and more in ocean engineering, but is limited by the performance of the existing steel, the steel for ocean engineering structure is mainly carbon steel, and some steel for ocean engineering cannot be completely protected against rust, so the engineering life is short. This severely limits the time and space that humans can move in the marine environment and also hinders the progress of marine development. Particularly, in the construction of south China sea, the demand for high corrosion resistant steel is urgent based on the marine environment with high temperature, high salt and high humidity.

for example, the same problems as described above are present in the construction of the mao bridge in hong kong zhu. 52 ten thousand tons of steel are used in the whole Gangzhao Australia bridge, but only 2205 duplex stainless steel of less than 1 ten thousand tons is used, mainly because the 2205 duplex stainless steel is expensive, is not suitable for being used in large quantity, and is not allowed in the aspect of construction cost. Therefore, the service life of the mao bridge is limited by the corrosion resistance of other carbon steel structures, and the service life is short, so that the design life of the mao bridge is only 120 years.

at present, the stainless steel buildings with the design life of more than hundreds of years exist abroad, and the construction cost is not high.

for example: bridges designed to have a life of 300 years have been built in the united states and australia, using 304 stainless steel, adding to the cost of about 5% or less of the total construction cost. This means that the construction works using stainless steel do not add much work cost.

Even longer-lived stainless steel buildings have begun to be constructed.

For example: a temple constructed in Thailand in recent years has a design life of 1000 years. Ottokupu 2101 stainless steel is used. This is the most typical case of a long-life building.

The current conventional stainless steel has the following problems:

The traditional stainless steel such as ferrite and austenite (304, 316 and 316L) stainless steel has too low strength, the yield strength which can be generally adopted is only 200-250MPa, and the constitutive curve is not an ideal constitutive curve required by engineering structural steel materials; the duplex stainless steel with an ideal structure curve has high manufacturing cost, is impossible to use on a large scale, and is not suitable for being used as long-life structural steel with excellent high temperature resistance, corrosion resistance and shock resistance for coastal and offshore building structures.

the coastline is within 60 kilometers, the cities are dense, 30% of people live, and more than 50% of buildings and wealth are collected; however, coastal areas are seriously corroded, and are areas with multiple earthquakes, and engineering such as buildings, bridges and the like are seriously threatened by earthquakes and corrosion at any moment. Therefore, the structural steel used in coastal and offshore structures needs to have good earthquake resistance and high temperature resistance in addition to the necessary prerequisite of corrosion resistance.

the invention aims to provide high-strength and high-toughness stainless structural steel which is suitable for coastal and offshore building structures, resists coastal high-temperature and high-humidity climate and general seawater corrosion and has the earthquake resistance function.

disclosure of Invention

The invention aims to solve the technical problem of how to provide a high-corrosion-resistance and shock-resistance high-strength and high-toughness stainless structural steel for a high-temperature, high-salt and high-humidity marine environment and solve the problem of short engineering life in marine development and construction.

The invention provides a high-toughness stainless structural steel of a marine tempered sorbite, which comprises the following basic components in percentage by mass: 0.07 to 0.16 weight percent of C, 0.4 to 1.5 weight percent of Si, less than or equal to 1.0 weight percent of Mn, 17.0 to 26.0 weight percent of Cr, 1.5 to 2.5 weight percent of Ni, less than or equal to 1.5 weight percent of Mo, 0.01 to 0.05 weight percent of Al, less than or equal to 0.05 weight percent of P, less than or equal to 0.020 weight percent of S, less than or equal to 40ppm of total O, and the balance of Fe and inevitable impurities.

preferably, the metallographic structure of the marine tempered sorbite high-strength and high-toughness stainless structural steel is chromium carbide which is uniformly distributed on a ferrite matrix and has the average size of 200-450 nm, and is also called tempered sorbite; the average grain size is less than 10 microns.

preferably, when the chromium content of the marine tempered sorbite high-strength stainless structural steel is 17-20 wt%, the neutral salt spray corrosion resistance is better than or equal to that of 2205 duplex stainless steel and 316 stainless steel, and the marine tempered sorbite high-strength stainless structural steel is suitable for common coastal environments; chromium content >20 wt% when used in a seawater environment and increases with increasing seawater temperature; the neutral salt spray corrosion resistance of the stainless steel with high chromium content is similar to that of austenitic 316L stainless steel and ferritic 447 stainless steel.

preferably, the marine tempered sorbite high-strength stainless structural steel is realized by controlling 0.7-1.5 wt% of silicon and 0.6-1.5 wt% of molybdenum and performing controlled rolling, controlled cooling and heat treatment for grain refining aiming at higher pitting corrosion resistance requirements.

Preferably, the yield strength Rp0.2 of the marine tempered sorbite high-strength and high-toughness stainless structural steel is more than or equal to 500MPa, the breaking strength Rm is more than or equal to 650MPa, the elongation is more than or equal to 18%, the reduction of area is more than or equal to 40%, and the impact absorption energy is more than or equal to 40J; meet the mechanical property required by the building structural steel and have the function of anti-seismic steel.

preferably, the preparation method of the marine tempered sorbite high-strength and high-toughness stainless structural steel comprises the following steps:

S1, taking the raw material As the surface layer ore of the low-phosphorus laterite-nickel ore, and requiring that heavy metal elements in the ore are As low As possible, so As to ensure that the total content of As, Sn, Pb, Sb and Bi in molten iron of a blast furnace or an electric furnace is not more than 150ppm and the single content is not more than 50 ppm; smelting into molten iron by a blast furnace or an ore-smelting electric furnace, and sending the molten iron to AOD for blowing; or molten iron obtained by smelting low-nickel iron blocks by an induction furnace and an electric arc furnace is sent to AOD for blowing; finishing the adjustment of the lower limit target of the components of main alloy elements C, Cr, Ni, Mn and Si of the marine tempered sorbite high-strength stainless structural steel in the AOD converting process;

s2, transferring the molten steel blown by the AOD in the S1 into an LF furnace, and enabling the carbon content and the phosphorus content of the molten steel entering the LF furnace to be below the final component lower limit, so as to prevent later-stage carburetion and leave the allowance for later-stage operation of C increase and P increase;

s3, adding 200-300 mm-thick reduction refining slag into the LF, and carrying out reduction refining on the molten steel entering the LF so as to carry out deoxidation and desulfurization and carry out accurate component adjustment; reducing refining slag with CaO/SiO alkalinity₂Controlling the content in the range of 2-3, wherein the components of the reduction refining slag are CaO: 50-60 wt% of high-quality CaCO₃The content ratio of CaO in the total amount is more than 50 wt%; SiO 2₂：25-30wt％；CaF₂: 10 wt%; the rest high-aluminum refractory brick block material; the lumpiness of the reduced refining slag is less than 20mm, powder materials cannot exist, and the reduced refining slag needs to be packaged in a sealed moisture-proof bag;

s4, blowing argon gas into the LF for stirring, wherein the argon gas blown into the LF is only required to be stirred to the extent that the slag surface is blown to be broken; then adding aluminum in a manner of adding 0.8-1.2kg of Al into each ton of steel, and in the subsequent process, adding no aluminum into molten steel for deoxidation; aluminum particles can be added to the surface of the LF slag when the formation of white slag is promoted, but aluminum powder cannot be used for replacing the aluminum particles, so that the aluminum powder is prevented from being violently combusted;

S5, blowing argon into the LF furnace, stirring for 10 minutes, then keeping white slag, adding limestone with high calcium proportion to adjust slag when the slag is too thin, so as to keep foamability of the slag, and smoothly refining and adjusting components of the LF furnace; keeping the time consumed by refining and adjusting the LF furnace to be not more than 40 minutes;

S6, after refining, performing denaturation treatment on inclusions in molten steel through an alkali metal cored wire to enable the components of the molten steel to meet the basic components of the marine tempered sorbite high-strength stainless structural steel;

the molten steel obtained after refining in S7 and S6 is sent to a continuous casting machine to be cast into a plate blank, a square blank or a rectangular blank;

S8, cooling the plate blank or the square blank or the rectangular blank, then checking and grinding the plate blank or the square blank or the rectangular blank, and then carrying out controlled rolling and controlled cooling rolling process and heat treatment in a rolling mill to prepare the required marine tempered sorbite high-strength and high-toughness stainless structural steel;

Preferably, in the rolling process and heat treatment of controlled rolling and controlled cooling of S8, for the steel with Si content less than 0.7 wt% and Mo content less than 0.6 wt%, the steel needs to be immediately cooled to 680-720 ℃ by spraying after finishing the finish rolling at 940 ℃ and then isothermal treatment is carried out for 2.5-5 hours.

Preferably, the rolling process of controlled rolling and controlled cooling of S8 requires that the heating furnace adopts three-stage heating, which is a first heating stage, a second heating stage and a third heating stage respectively; wherein: the temperature of the first heating section is less than or equal to 900 ℃, the temperature of the second heating section is 1200-1240 ℃, the temperature of the third heating section is 1220-1240 ℃, the heating speed is 16min/cm, and the highest heating temperature is strictly 1250 ℃; the percentage of the three heating times in the total heating time is as follows: the first heating section accounts for 50%, the second heating section accounts for 25%, and the third heating section accounts for 25%.

Preferably, in the rolling process and heat treatment of controlled rolling and controlled cooling of S8, for the steel material with Si content greater than or equal to 0.7 wt% and Mo content of 0.6-1.5 wt%, after finishing rolling at 940 ℃, heating to 1020 ℃ -1050 ℃, preserving heat for 1-1.5 hours, immediately spraying and cooling to 680-.

Preferably, in the rolling process and the heat treatment of controlled rolling and controlled cooling of S8, for medium and heavy plates and other large-sized steel products and steel products with higher mechanical property requirements, the steel products are immediately cut to length and cooled to room temperature by spraying after rolling; then heating to 1040-1140 deg.C, and heat-insulating for 1-1.5 hr; then quenching water and cooling to room temperature; then the temperature is increased to 680 ℃ and 740 ℃, and the temperature is preserved for 3 to 5 hours; then, the mixture is quenched again to 200 ℃ or lower.

preferably, the refining in the preparation method of the marine tempered sorbite high-strength and high-toughness stainless structural steel enables the contents of inclusions and oxygen and sulfur in the steel to reach a high purity level, the total oxygen content is less than 40ppm, S is less than or equal to 0.020 wt%, and P is less than or equal to 0.05 wt%; according to the ASTM-E45 inclusion test standard, the grades of various inclusions such as medium plates, bars and the like are all below 1.5 grade.

the technical scheme of the invention has the following beneficial effects:

The invention provides a high-strength and high-toughness stainless structural steel which is suitable for coastal and offshore building structures, resists coastal climate and general seawater corrosion and has the earthquake resistance function. The high-strength and high-toughness stainless structural steel of the marine tempered sorbite provided by the invention meets the urgent requirements of high-temperature, high-salt and high-humidity marine environments on high-corrosion-resistant steel, can be widely applied to engineering construction of coastal and island buildings, bridges and the like in China and the world, greatly prolongs the safe life of the engineering, does not coat or rarely coats anti-rust paint, greatly expands the living space of human beings, and ensures that the wealth of the human beings is accumulated and carried in the form of a long-life building.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description is given with reference to specific embodiments.

the invention aims to solve the technical problem of how to provide a high-corrosion-resistance and shock-resistance high-strength and high-toughness stainless structural steel for a high-temperature, high-salt and high-humidity marine environment and solve the problem of short engineering life in marine development and construction.

The invention provides a high-toughness stainless structural steel of a marine tempered sorbite, which comprises the following basic components in percentage by mass: 0.07 to 0.16 weight percent of C, 0.4 to 1.5 weight percent of Si, less than or equal to 1.0 weight percent of Mn, 17.0 to 26.0 weight percent of Cr, 1.5 to 2.5 weight percent of Ni, less than or equal to 1.5 weight percent of Mo, 0.01 to 0.05 weight percent of Al, less than or equal to 0.05 weight percent of P, less than or equal to 0.020 weight percent of S, less than or equal to 40ppm of total O, and the balance of Fe and inevitable impurities.

wherein the metallographic structure of the marine tempered sorbite high-strength and high-toughness stainless structural steel is chromium carbide which is uniformly distributed on a ferrite matrix and has the average size of 200-450 nm, and is also called tempered sorbite; the average grain size is less than 10 microns.

Wherein when the chromium content of the marine tempered sorbite high-strength stainless structural steel is 17-20 wt%, the neutral salt spray corrosion resistance is superior to or equal to 2205 duplex stainless steel and 316 stainless steel, and the marine tempered sorbite high-strength stainless structural steel is suitable for common coastal environments; chromium content >20 wt% when used in a seawater environment and increases with increasing seawater temperature; the neutral salt spray corrosion resistance of the stainless steel with high chromium content is similar to that of austenitic 316L stainless steel and ferritic 447 stainless steel.

The high-toughness stainless structural steel of the marine tempered sorbite is realized by controlling 0.7-1.5 wt% of silicon and 0.6-1.5 wt% of molybdenum and performing controlled rolling, controlled cooling and heat treatment for grain refining aiming at higher pitting corrosion resistance.

The yield strength Rp0.2 of the marine tempered sorbite high-strength and high-toughness stainless structural steel is more than or equal to 500MPa, the breaking strength Rm is more than or equal to 650MPa, the elongation is more than or equal to 18%, the reduction of area is more than or equal to 40%, and the impact absorption energy is more than or equal to 40J; meet the mechanical property required by the building structural steel and have the function of anti-seismic steel.

The preparation method of the marine tempered sorbite high-strength and high-toughness stainless structural steel comprises the following steps:

S1, taking the raw material As the surface layer ore of the low-phosphorus laterite-nickel ore, and requiring that heavy metal elements in the ore are As low As possible, so As to ensure that the total content of As, Sn, Pb, Sb and Bi in molten iron of a blast furnace or an electric furnace is not more than 150ppm and the single content is not more than 50 ppm; smelting into molten iron by a blast furnace or an ore-smelting electric furnace, and sending the molten iron to AOD for blowing; or molten iron obtained by smelting low-nickel iron blocks by an induction furnace and an electric arc furnace is sent to AOD for blowing; finishing the adjustment of the lower limit target of the components of main alloy elements C, Cr, Ni, Mn and Si of the marine tempered sorbite high-strength stainless structural steel in the AOD converting process;

S2, transferring the molten steel blown by the AOD in the S1 into an LF furnace, and enabling the carbon content and the phosphorus content of the molten steel entering the LF furnace to be below the final component lower limit, so as to prevent later-stage carburetion and leave the allowance for later-stage operation of C increase and P increase;

S3, adding 200-300 mm-thick reduction refining slag into the LF, and carrying out reduction refining on the molten steel entering the LF so as to carry out deoxidation and desulfurization and carry out accurate component adjustment; reducing refining slag with CaO/SiO alkalinity₂Controlling the content in the range of 2-3, wherein the components of the reduction refining slag are CaO: 50-60 wt% of high-quality CaCO₃The content ratio of CaO in the total amount is more than 50 wt%; SiO 2₂：25-30wt％；CaF₂: 10 wt%; the rest high-aluminum refractory brick block material; the lumpiness of the reduced refining slag is less than 20mm, powder materials cannot exist, and the reduced refining slag needs to be packaged in a sealed moisture-proof bag;

s4, blowing argon gas into the LF for stirring, wherein the argon gas blown into the LF is only required to be stirred to the extent that the slag surface is blown to be broken; then adding aluminum in a manner of adding 0.8-1.2kg of Al into each ton of steel, and in the subsequent process, adding no aluminum into molten steel for deoxidation; aluminum particles can be added to the surface of the LF slag when the formation of white slag is promoted, but aluminum powder cannot be used for replacing the aluminum particles, so that the aluminum powder is prevented from being violently combusted;

s5, blowing argon into the LF furnace, stirring for 10 minutes, then keeping white slag, adding limestone with high calcium proportion to adjust slag when the slag is too thin, so as to keep foamability of the slag, and smoothly refining and adjusting components of the LF furnace; keeping the time consumed by refining and adjusting the LF furnace to be not more than 40 minutes;

S6, after refining, performing denaturation treatment on inclusions in molten steel through an alkali metal cored wire to enable the components of the molten steel to meet the basic components of the marine tempered sorbite high-strength stainless structural steel;

the molten steel obtained after refining in S7 and S6 is sent to a continuous casting machine to be cast into a plate blank, a square blank or a rectangular blank;

S8, cooling the plate blank or the square blank or the rectangular blank, then checking and grinding the plate blank or the square blank or the rectangular blank, and then carrying out controlled rolling and controlled cooling rolling process and heat treatment in a rolling mill to prepare the required marine tempered sorbite high-strength and high-toughness stainless structural steel;

The rolling process of controlled rolling and controlled cooling of S8 requires that the heating furnace adopts three-stage heating, wherein the three-stage heating is a first heating stage, a second heating stage and a third heating stage respectively; wherein: the temperature of the first heating section is less than or equal to 900 ℃, the temperature of the second heating section is 1200-1240 ℃, the temperature of the third heating section is 1220-1240 ℃, the heating speed is 16min/cm, and the highest heating temperature is strictly 1250 ℃; the percentage of the three heating times in the total heating time is as follows: the first heating section accounts for 50%, the second heating section accounts for 25%, and the third heating section accounts for 25%.

In the rolling process and the heat treatment of controlled rolling and controlled cooling of S8, for the steel with the Si content lower than 0.7 wt% and the Mo content lower than 0.6 wt%, the steel needs to be immediately cooled to 680-720 ℃ by spraying after the finish rolling at 940 ℃ and then isothermal treatment is carried out for 2.5-5 hours.

In the rolling process and the heat treatment of the controlled rolling and the controlled cooling of S8, for the steel with the Si content more than or equal to 0.7 wt% and the Mo content of 0.6-1.5 wt%, after finishing the finish rolling at 940 ℃, the temperature is raised to 1020-1050 ℃, the heat is preserved for 1-1.5 hours, and then the steel is immediately sprayed and cooled to 680-720 ℃, and isothermal treatment is carried out for 2.5-5 hours.

in the rolling process and the heat treatment of the controlled rolling and the controlled cooling of S8, for medium and heavy plates, other large-size steel and steel with higher mechanical property requirements, the steel is immediately cut to length and cooled to room temperature after being rolled; then heating to 1040-1140 deg.C, and heat-insulating for 1-1.5 hr; then quenching water and cooling to room temperature; then the temperature is increased to 680 ℃ and 740 ℃, and the temperature is preserved for 3 to 5 hours; then, the mixture is quenched again to 200 ℃ or lower.

Wherein, the refining in the preparation method ensures that the contents of inclusions and oxygen and sulfur in the steel reach a high purity level, the total oxygen content is less than 40ppm, S is less than or equal to 0.020 wt%, and P is less than or equal to 0.05 wt%; according to the ASTM-E45 inclusion test standard, the grades of various inclusions such as medium plates, bars and the like are all below 1.5 grade.

The specific marine tempered sorbite high-strength and high-toughness stainless structural steel and the preparation method thereof are explained by combining the following embodiments: