A method for preparing corrosion-resistant alloy steel

Abstract

This invention discloses a method for preparing corrosion-resistant alloy steel. The elemental composition and weight percentages of the alloy steel are as follows: C: 0.10-0.25%, Mn: 0.5-1.0%, Si: 0.2-0.5%, Cr: 0.8-1.2%, Mo: 0.10-0.15%, Ni: 0.40-0.65%, V: 0.01-0.08%, Ti: 0.01-0.08%, Sn: 0.1-0.2%, B: 0.008-0.01%, with the balance being iron. The preparation method includes: melting and casting ingots, austenitizing, hot forging, hot rolling, large deformation rolling, and tempering. The method for preparing corrosion-resistant alloy steel of the present invention achieves excellent corrosion resistance while ensuring the mechanical stability of stainless steel by controlling the types and contents of elements added to the steel and improving the preparation method. The average yield strength of the alloy steel can reach about 1080 MPa and the average tensile strength can reach about 1350 MPa. Appropriately increasing the Sn content in the alloy steel will promote the formation of a dense protective rust layer through the synergistic effect of Sn, Cr, and Mo. Adding a small amount of B can replace some of the precious elements Ni, Cr, and Mo, thereby reducing the production cost of the alloy steel.

Description

Technical Field

[0001] This invention relates to the field of special stainless steel and its processing technology, and in particular to a method for preparing corrosion-resistant alloy steel. Background Technology

[0002] Alloy steel is steel with alloying elements added in addition to iron and carbon. Depending on the added elements, the content of these elements, and appropriate processing techniques, alloy steels with special properties such as high strength, high toughness, wear resistance, corrosion resistance, low-temperature resistance, high-temperature resistance, and non-magnetic properties can be obtained to suit different applications. When the total content of alloying elements is below 5%, it is called low-alloy steel. Due to its low alloy content, low manufacturing cost, and simple preparation process, alloy steel is characterized by good strength, impact toughness, and excellent weldability. It is one of the important engineering structural materials and is widely used in bridges, storage tanks, ships, vessels, oil and gas pipelines, etc.

[0003] As a vital component of the marine economy, the marine engineering construction industry boasts broad development prospects, which will greatly promote the prosperity and development of the supporting marine structural steel reinforcement industry. Alloy steel also has extensive application prospects in shipbuilding and other related industries. Reinforcing steel materials for marine engineering are mainly used in coastal, near-shore, and offshore marine engineering construction, where the service environment is extremely harsh. High chloride ion concentrations, high temperatures, high humidity, surges, splashes, and abundant marine life all pose severe challenges to the corrosion resistance and mechanical properties of reinforcing steel materials. Steel is highly susceptible to corrosion in marine environments, leading to structural performance degradation and significantly shortening the service life of steel structural components.

[0004] Therefore, for stainless steel materials used in marine engineering, in addition to mechanical properties, excellent corrosion resistance is also a crucial application requirement. Adding small amounts of corrosion-resistant elements such as Cu, Cr, Ni, Mo, and Al to steel can improve its corrosion resistance. Under the influence of external corrosive environments, these corrosion-resistant elements undergo chemical reactions, forming a dense and well-bonded corrosion product layer on the steel surface. This layer mainly consists of α-FeOOH, β-FeOOH, γ-FeOOH, Fe3O4, and some amorphous substances, with α-FeOOH exhibiting the highest corrosion resistance. Furthermore, recent studies have found that tin (Sn), as a low-cost element, can effectively improve the corrosion resistance of steel, preventing the rust layer of alloy steel from being destroyed by corrosive ions in polluted atmospheric environments, thus extending its service life. However, during steelmaking, tin is generally considered a harmful impurity element in steel. It affects the quality of steel, especially the quality of continuously cast billets, causing hot brittleness, temper brittleness, cracks and fractures, and affecting the weldability of steel; it is one of the "five evils" of steel. The grain size in steel is related to tin segregation, which hinders grain growth. Higher tin content results in greater grain precipitation, effectively inhibiting grain growth; smaller grains lead to less iron loss. Therefore, for alloy steels used in marine engineering, it is essential to produce alloy steels with both excellent mechanical properties and excellent corrosion resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing corrosion-resistant alloy steel. By controlling the types and contents of elements added to the steel and improving the traditional preparation method of alloy steel, excellent corrosion resistance can be achieved while ensuring the mechanical stability of stainless steel.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing corrosion-resistant alloy steel, wherein the elemental composition and weight proportions of the corrosion-resistant alloy steel are as follows:

[0007] C: 0.10-0.25%, Mn: 0.5-1.0%, Si: 0.2-0.5%, Cr: 0.8-1.2%, Mo: 0.10-0.15%, Ni: 0.40-0.65%, V: 0.01-0.08%, Ti: 0.01-0.08%, Sn: 0.1-0.2%, B: 0.008-0.01%, with the balance being iron; the preparation method of the corrosion-resistant alloy steel includes the following steps:

[0008] S1: Melting and casting ingots: The alloy steel is prepared according to the mass percentage content of each component, melted in a vacuum induction furnace and then cast into ingots.

[0009] S2: Austenitization: Heat the ingot to 1200-1250℃, hold for 2.5-4 hours to complete the austenitization of the microstructure, and then isothermally cool to room temperature;

[0010] S3: Hot forging of billet: Heat the ingot billet to 1170℃~1230℃ and hold for 2~3 hours; then hot forge, with a final forging temperature of not less than 1150℃;

[0011] S4: Multi-pass hot rolling: The billet is heated to 1100-1200℃, held for 1.0h-2.0h, and then taken out of the furnace for 7-10 passes of continuous hot rolling. The initial rolling temperature is 1050-1180℃, and the final rolling temperature is not lower than 900℃. After rolling, the billet is water quenched to room temperature.

[0012] Preferably, the corrosion-resistant alloy steel has the following elemental composition and weight percentages: C: 0.12%, Mn: 0.5%, Si: 0.4%, Cr: 1.0%, Mo: 0.10%, Ni: 0.40%, V: 0.03%, Ti: 0.03%, Sn: 0.15%, B: 0.008%, with the balance being iron.

[0013] More preferably, the corrosion-resistant alloy steel has the following elemental composition and weight percentages: C: 0.15%, Mn: 0.6%, Si: 0.3%, Cr: 1.2%, Mo: 0.12%, Ni: 0.5%, V: 0.03%, Ti: 0.03%, Sn: 0.18%, B: 0.008%, with the balance being iron.

[0014] More preferably, step S5 is included after step S4: large deformation rolling, with a rolling deformation of not less than 75%.

[0015] More preferably, step S5 is followed by step S6: heating the material to 900°C, holding it at that temperature for 15–25 min, and then water quenching it; then tempering it at 180–200°C for 30–60 min.

[0016] More preferably, the corrosion-resistant alloy steel has the following elemental composition and weight percentages: C: 0.12%, Mn: 0.5%, Si: 0.4%, Cr: 1.0%, Mo: 0.10%, Ni: 0.40%, V: 0.03%, Ti: 0.03%, Sn: 0.15%, B: 0.008%, with the balance being iron.

[0017] More preferably, the corrosion-resistant alloy steel has the following elemental composition and weight percentages: C: 0.15%, Mn: 0.6%, Si: 0.3%, Cr: 1.2%, Mo: 0.12%, Ni: 0.5%, V: 0.03%, Ti: 0.03%, Sn: 0.18%, B: 0.008%, with the balance being iron.

[0018] In a preferred embodiment, a method for preparing a corrosion-resistant alloy steel, wherein the elemental composition and weight percentages of the corrosion-resistant alloy steel are as follows:

[0019] C: 0.16%, Mn: 0.8%, Si: 0.25%, Cr: 1.0%, Mo: 0.10%, Ni: 0.405%, V: 0.03%, Ti: 0.02%, Sn: 0.18%, B: 0.009%, balance being iron; the preparation method of the corrosion-resistant alloy steel is as follows:

[0020] S1: Melting and casting ingots: The alloy steel is prepared according to the mass percentage content of each component, melted in a vacuum induction furnace and then cast into ingots.

[0021] S2: Austenitization: Heat the ingot to 1200℃, hold for 3 hours to complete the austenitization of the microstructure, and then cool isothermally to room temperature;

[0022] S3: Hot forging of billet: The ingot billet is heated to 1190℃ and held for 2.5h; then hot forging is carried out, and the final forging temperature is not lower than 1150℃;

[0023] S4: Multi-pass hot rolling: The billet is heated to 1150℃, held for 1.5h, and then taken out of the furnace for 10 consecutive hot rolling passes. The initial rolling temperature is 1060℃ and the final rolling temperature is 900℃. After rolling, the billet is water quenched to room temperature.

[0024] S5: Large deformation rolling, with a rolling deformation of not less than 80%; and,

[0025] S6: Heat the material to 900℃, hold for 20 minutes, then quench in water; then temper at 200℃ for 45 minutes.

[0026] More preferably, the alloy steel has an average yield strength of about 1080 MPa and an average tensile strength of about 1350 MPa.

[0027] The method for preparing corrosion-resistant alloy steel of the present invention, by controlling the types and contents of elements added to the steel and improving the traditional preparation method of alloy steel, can achieve excellent corrosion resistance while ensuring the mechanical stability of stainless steel. The average yield strength of the alloy steel can reach about 1080 MPa, and the average tensile strength can reach about 1350 MPa. While maintaining excellent mechanical properties, appropriately increasing the Sn content in the alloy steel will promote the formation of a dense protective rust layer due to the synergistic effect of Sn, Cr, and Mo. Adding a small amount of B can replace some of the precious elements Ni, Cr, and Mo, thereby reducing the production cost of alloy steel. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention proposes a method for preparing corrosion-resistant alloy steel, wherein the elemental composition and weight proportions of the corrosion-resistant alloy steel are as follows:

[0030] C: 0.10-0.25%, Mn: 0.5-1.0%, Si: 0.2-0.5%, Cr: 0.8-1.2%, Mo: 0.10-0.15%, Ni: 0.40-0.65%, V: 0.01-0.08%, Ti: 0.01-0.08%, Sn: 0.1-0.2%, B: 0.008-0.01%, balance is iron.

[0031] The role of alloying elements in duplex stainless steel has been experimentally demonstrated as follows:

[0032] C is the most important solid solution strengthening element for enhancing the toughness of duplex steel and for improving the hardenability of austenite. In addition, C forms carbonitrides with microalloyed Ti during heat treatment, which refines the grains and strengthens ferrite. Considering that excessive C content should be avoided to prevent the material from deteriorating in weldability and forming banded structures that worsen formability, the C content in the alloy steel of this invention is controlled at 0.12 to 0.25%.

[0033] Si can effectively promote the enrichment of C into austenite, improve the hardenability of austenite, purify the ferrite phase, and improve elongation. However, if the Si content is too high, iron oxide scale will be formed during the hot rolling heating process and is difficult to remove. In addition, in alloy steel with high Si content, Sn segregation can hinder grain growth and refine grains. Therefore, the Si content in the alloy steel of this invention is controlled at 0.2 to 0.5%.

[0034] Mn is also an important element for stabilizing austenite, but excessive Mn content can easily cause microstructure segregation, leading to forming cracks and deteriorating the overall performance of the steel. It can also accumulate on the surface during annealing. Therefore, the Mn content should not be too high. The Mn content in the alloy steel of this invention is controlled at 0.5 to 1.0%.

[0035] Sn can improve the toughness, machinability, and wear resistance of steel, as well as its corrosion resistance and durability. However, excessive Sn content can cause hot brittleness, temper brittleness, cracks, and fractures, affecting the weldability of the steel. Therefore, the Sn content in the alloy steel of this invention is controlled at 0.1-0.2%.

[0036] Ti, as a microalloying element, can combine with C to form nano-precipitates, which can refine grains and strengthen them through precipitation. It has a significant effect on improving microstructure and increasing yield strength. However, if the content is too high, it will have an adverse effect on elongation. Therefore, the Ti content in the alloy steel of this invention needs to be controlled between 0.01 and 0.08%.

[0037] Mo can also improve the hardenability of austenite and inhibit the enrichment of interface elements in high silicon content steel during hot rolling heating, forming a Mo enrichment zone, inhibiting the diffusion of Si elements to the iron scale side, and inhibiting the formation of indelible red phosphorus defects; therefore, the Mo content in the alloy steel of this invention is controlled at 0.1 to 0.15%.

[0038] Cr is an important element for improving the corrosion resistance of stainless steel. Adding Cr to steel can induce an amorphous transformation of corrosion products, forming a more stable rust layer. This not only improves the protective properties of the rust layer but also imparts cation selectivity to it, thereby enhancing its corrosion resistance. In this invention, the Cr content in the alloy steel is controlled at 0.8–1.2%.

[0039] Ni is also an effective element for improving the corrosion resistance of steel. Adding Ni to steel can change the self-corrosion potential of steel in a more positive direction. Adding Ni can cause the formation of a stable NiFe2O4 phase in spinel-type oxides in the rust layer, promoting the transformation of spinel into a fine and dense structure, thereby improving the stability of the rust layer and achieving corrosion resistance. The Ni content in the alloy steel of this invention is controlled at 0.4% to 0.65%.

[0040] Vanadium (V) can improve the resistance of stainless steel to intergranular corrosion. A small amount of vanadium can refine the grains and increase toughness. When carbides are dispersed and precipitated through appropriate heat treatment, the high-temperature creep strength and creep resistance of the steel can be improved. However, a high vanadium content can lead to the formation of aggregated carbides, which reduces strength. Intragranular precipitation of carbides can reduce room temperature toughness. In the alloy steel of this invention, the V content is controlled at 0.01–0.08%.

[0041] The main role of boron in steel is to increase its hardenability, thereby saving other rarer and more expensive metals such as nickel, chromium, and molybdenum, and reducing costs. However, boron tends to promote temper brittleness and cannot completely replace molybdenum; a certain molybdenum content needs to be maintained. In addition, since the effect of boron weakens with the increase of carbon content in steel, it is generally used in steels with low carbon content.

[0042] The method for preparing the corrosion-resistant alloy steel of the present invention is as follows:

[0043] S1: Melting and casting ingots: The alloy steel is prepared according to the mass percentage content of each component, melted in a vacuum induction furnace and then cast into ingots.

[0044] S2: Austenitization: Heat the ingot to 1200-1250℃, hold for 2.5-4 hours to complete the austenitization of the microstructure, and then isothermally cool to room temperature;

[0045] S3: Hot forging of billet: Heat the ingot billet to 1170℃~1230℃ and hold for 2~3 hours; then hot forge, with a final forging temperature of not less than 1150℃;

[0046] S4: Multi-pass hot rolling: The billet is heated to 1100-1200℃, held for 1.0h-2.0h, and then taken out of the furnace for 7-10 passes of continuous hot rolling. The initial rolling temperature is 1050-1180℃, and the final rolling temperature is not lower than 900℃. After rolling, the billet is water quenched to room temperature.

[0047] In a preferred embodiment, step S5 is further included after step S4: large deformation rolling, with a rolling deformation of not less than 75%; the effect of refining the microstructure can be achieved through large deformation rolling.

[0048] More preferably, step S6 is included after step S5: heating the material to 900°C, holding it at that temperature for 15–25 min, and then water quenching it; followed by tempering at 180–200°C for 30–60 min. This heat treatment process can improve the mechanical properties of alloy steel.

[0049] Preferably, the corrosion-resistant alloy steel has the following elemental composition and weight percentages: C: 0.12%, Mn: 0.5%, Si: 0.4%, Cr: 1.0%, Mo: 0.10%, Ni: 0.40%, V: 0.03%, Ti: 0.03%, Sn: 0.15%, B: 0.008%, with the balance being iron.

[0050] More preferably, the corrosion-resistant alloy steel has the following elemental composition and weight percentages: C: 0.15%, Mn: 0.6%, Si: 0.3%, Cr: 1.2%, Mo: 0.12%, Ni: 0.5%, V: 0.03%, Ti: 0.03%, Sn: 0.18%, B: 0.008%, with the balance being iron.

[0051] More preferably, step S4 is included after step S3: large deformation rolling, with a rolling deformation of not less than 75%.

[0052] More preferably, step S5 is included after step S4: heating the material to 900°C, holding it at that temperature for 15-25 minutes, and then water quenching it; then tempering it at 180-200°C for 30-60 minutes.

[0053] In a preferred embodiment, a method for preparing a corrosion-resistant alloy steel, wherein the elemental composition and weight percentages of the corrosion-resistant alloy steel are as follows:

[0054] C: 0.16%, Mn: 0.8%, Si: 0.25%, Cr: 1.0%, Mo: 0.10%, Ni: 0.405%, V: 0.03%, Ti: 0.02%, Sn: 0.18%, B: 0.009%, balance being iron; the preparation method of the corrosion-resistant alloy steel is as follows:

[0055] S1: Melting and casting ingots: The alloy steel is prepared according to the mass percentage content of each component, melted in a vacuum induction furnace and then cast into ingots.

[0056] S2: Austenitization: Heat the ingot to 1200℃, hold for 3 hours to complete the austenitization of the microstructure, and then cool isothermally to room temperature;

[0057] S3: Hot forging of billet: The ingot billet is heated to 1190℃ and held for 2.5h; then hot forging is carried out, and the final forging temperature is not lower than 1150℃;

[0058] S4: Multi-pass hot rolling: The billet is heated to 1150℃, held for 1.5h, and then taken out of the furnace for 10 consecutive hot rolling passes. The initial rolling temperature is 1060℃ and the final rolling temperature is 900℃. After rolling, the billet is water quenched to room temperature.

[0059] S5: Large deformation rolling, with a rolling deformation of not less than 80%; and,

[0060] S6: Heat the material to 900℃, hold for 20 minutes, then quench in water; then temper at 200℃ for 45 minutes.

[0061] Tests showed that the average yield strength of the alloy steel was around 1080 MPa and the average tensile strength was around 1350 MPa. When the Sn content in the steel exceeded 0.2%, the toughness at low temperatures decreased significantly.

[0062] The obtained alloy steel was subjected to corrosion resistance tests according to GB / T19746-2018. The rust layer of the alloy steel after immersion corrosion was analyzed. When the Sn content in the alloy steel is higher, the thickness of the rust layer increases significantly. Moreover, the rust layer exhibits a two-layer structure. The outer rust layer is in direct contact with the external environment and is relatively loose and porous, while the inner rust layer is tightly bonded to the steel substrate and is relatively dense. This inner rust layer can effectively block the intrusion of corrosive ions, thereby slowing down corrosion and improving the corrosion resistance of the test steel. Furthermore, the thickness of the inner rust layer also increases with the longer the corrosion time, thus improving the corrosion resistance. When the Sn content in the alloy steel is less than 0.08%, the thickness of the inner rust layer decreases significantly, resulting in poor corrosion resistance. Moreover, the thickness of the inner rust layer does not change significantly with the longer the corrosion time, meaning that the corrosion resistance of the alloy steel does not improve significantly.

[0063] Analysis of the rust layer in corroded alloy steel revealed that when the Sn content in the alloy steel was high, Cr was significantly enriched in the inner rust layer adjacent to the substrate, while Cl was uniformly distributed within the rust layer. This indicates that Cr participated in the formation of the rust layer. The enrichment of Cr in the rust layer helps to refine the rust layer structure, promotes the formation of α-FeOOH and γ-FeOOH with higher corrosion resistance, and forms an ultrafine structure, which helps to improve the corrosion resistance of the alloy steel. Moreover, Sn enrichment was also observed in the inner rust layer, indicating that Sn-containing corrosion products are also an important component of the inner rust layer. The synergistic effect of Sn, Cr, and Mo promotes the formation of a protective rust layer. When the Sn content in the alloy steel was low, the enrichment of Sn and Cr in the inner rust layer was not obvious, thus exhibiting poor corrosion resistance.

[0064] The method for preparing corrosion-resistant alloy steel of the present invention, by controlling the types and contents of elements added to the steel and improving the traditional preparation method of alloy steel, can achieve excellent corrosion resistance while ensuring the mechanical stability of stainless steel. The average yield strength of the alloy steel can reach about 1080 MPa, and the average tensile strength can reach about 1350 MPa. While maintaining excellent mechanical properties, appropriately increasing the Sn content in the alloy steel will promote the formation of a dense protective rust layer due to the synergistic effect of Sn, Cr, and Mo. Adding a small amount of B can replace some of the precious elements Ni, Cr, and Mo, thereby reducing the production cost of alloy steel.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing corrosion-resistant alloy steel, characterized in that, The elemental composition and weight fraction of the corrosion-resistant alloy steel are as follows: C: 0.10-0.25%, Mn: 0.5-1.0%, Si: 0.2-0.5%, Cr: 0.8-1.2%, Mo: 0.10-0.15%, Ni: 0.40-0.65%, V: 0.01-0.08%, Ti: 0.01-0.08%, Sn: 0.1-0.2%, B: 0.008-0.01%, with the balance being iron. The preparation method of the corrosion-resistant alloy steel includes the following steps: S1: Melting and casting ingots: The raw materials are prepared according to the mass percentage content of each component in the corrosion-resistant alloy steel, and then melted in a vacuum induction furnace and cast into ingots. S2: Austenitization: Heat the ingot to 1200-1250℃, hold for 2.5-4 hours to complete the austenitization of the microstructure, and then isothermally cool to room temperature; S3: Hot forging of billet: Heat the ingot billet to 1170℃~1230℃ and hold for 2~3 hours; then hot forge, with a final forging temperature of not less than 1150℃; S4: Multi-pass hot rolling: The billet is heated to 1100-1200℃, held for 1.0h-2.0h, and then taken out of the furnace for 7-10 passes of continuous hot rolling. The initial rolling temperature is 1050-1180℃, and the final rolling temperature is not lower than 900℃. After rolling, the billet is water quenched to room temperature.

2. The method for preparing a corrosion-resistant alloy steel as described in claim 1, characterized in that, Step S4 is followed by step S5: large deformation rolling, with a rolling deformation of not less than 75%.

3. The method for preparing a corrosion-resistant alloy steel as described in claim 2, characterized in that, The process includes step S6 after step S5: heating the material to 900°C, holding it at that temperature for 15–25 min, and then water quenching it; followed by tempering at 180–200°C for 30–60 min.

4. The method for preparing a corrosion-resistant alloy steel as described in claim 1, characterized in that, The corrosion-resistant alloy steel has the following elemental composition and weight fraction: C: 0.12%, Mn: 0.5%, Si: 0.4%, Cr: 1.0%, Mo: 0.10%, Ni: 0.40%, V: 0.03%, Ti: 0.03%, Sn: 0.15%, B: 0.008%, with the balance being iron.

5. The method for preparing a corrosion-resistant alloy steel as described in claim 1, characterized in that, The corrosion-resistant alloy steel has the following elemental composition and weight fraction: C: 0.15%, Mn: 0.6%, Si: 0.3%, Cr: 1.2%, Mo: 0.12%, Ni: 0.5%, V: 0.03%, Ti: 0.03%, Sn: 0.18%, B: 0.008%, with the balance being iron.

6. A method for preparing a corrosion-resistant alloy steel, characterized in that, The elemental composition and weight fraction of the corrosion-resistant alloy steel are as follows: C: 0.16%, Mn: 0.8%, Si: 0.25%, Cr: 1.0%, Mo: 0.10%, Ni: 0.405%, V: 0.03%, Ti: 0.02%, Sn: 0.18%, B: 0.009%, with the balance being iron. The preparation method of the corrosion-resistant alloy steel is as follows: S1: Melting and casting ingots: The raw materials are prepared according to the mass percentage content of each component in the corrosion-resistant alloy steel, and then melted in a vacuum induction furnace and cast into ingots. S2: Austenitization: Heat the ingot to 1200℃, hold for 3 hours to complete the austenitization of the microstructure, and then cool isothermally to room temperature; S3: Hot forging of billet: The ingot billet is heated to 1190℃ and held for 2.5h; then hot forging is carried out, and the final forging temperature is not lower than 1150℃; S4: Multi-pass hot rolling: The billet is heated to 1150℃, held for 1.5h, and then taken out of the furnace for 10 consecutive hot rolling passes. The initial rolling temperature is 1060℃ and the final rolling temperature is 900℃. After rolling, the billet is water quenched to room temperature. S5: Large deformation rolling, with a rolling deformation of not less than 80%; and, S6: Heat the material to 900℃, hold for 20 minutes, then quench in water; then temper at 200℃ for 45 minutes.

7. The method for preparing a corrosion-resistant alloy steel as described in claim 6, characterized in that, The average yield strength of the obtained corrosion-resistant alloy steel is about 1080 MPa, and the average tensile strength is about 1350 MPa.