CN115074641A

CN115074641A - HB 400-grade high-wear-resistance cold-bending steel plate and production method thereof

Info

Publication number: CN115074641A
Application number: CN202210756320.4A
Authority: CN
Inventors: 张涛; 纪汶伯; 杨颖�; 林田子; 张哲�; 王玉博
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2022-09-20
Anticipated expiration: 2042-06-30
Also published as: CN115074641B

Abstract

A HB400 grade high abrasion resistance cold-bending steel plate and its production method, the chemical composition in the steel is calculated according to the weight percent C0.14% -0.18%, Si 1.1% -1.50%, Mn0.7% -1.0%, Nb0.12% -0.20%, Cr0.15% -0.35%, Ni0.4% -0.6%; 0.03 percent or less of C and Nb, 2.0 percent or less of Si and Ni with the concentration of 1.5 percent or more, 0.040 to 0.060 percent of Al0, and the balance of Fe and inevitable impurities. Compared with the prior art, the invention has the beneficial effects that: continuous casting production can be carried out; the surface hardness is more than HB400, and the AKV is more than or equal to 40J at the temperature of minus 40 ℃; the wear resistance is more than 1.4 times of that of the low-alloy wear-resistant steel plate with the same hardness; the product has good cold forming performance and is qualified when the cold bending D of 180 degrees is 3 a.

Description

HB 400-grade high-wear-resistance cold-bending steel plate and production method thereof

Technical Field

The invention belongs to the field of metal materials, and particularly relates to an HB400 grade high-wear-resistance cold-bending steel plate and a production method thereof, which can be used for manufacturing wear-resistant spare parts in the fields of engineering machinery, mines, metallurgy, coal machines and the like.

Background

The general low-alloy wear-resistant steel is produced by adopting a martensite matrix and low-hardness carbides such as Cr, Mo, V, Ti and the like to strengthen the wear resistance and adopting a heat treatment mode of quenching and low-temperature tempering, the service life of the general low-alloy Brinell wear-resistant steel with the HB400 hardness level is about 2 times of that of Q345B, and the low-alloy Brinell wear-resistant steel is widely applied in the fields of engineering machinery, coal mine machinery and the like, but the cold bending performance is relatively poor. The improvement of the wear resistance of the wear-resistant steel can be generally realized by increasing the carbon content and the alloy content of the steel plate, so that the processing performance and the welding performance of the steel are poor, and the cold-bending forming performance is worse.

In recent years, in the production process of the industries such as road building machinery, heavy mine cars, coal mining machines, power plants, cement and the like, materials are hard, the movement is fast, the equipment is very seriously abraded, the spare parts are quickly abraded, the overhaul period is short, a high-abrasion-resistance HB 400-grade abrasion-resistant steel plate is urgently needed, and the service life of the spare parts is prolonged under the condition that the hardness is not increased. Meanwhile, part of wear-resistant spare parts with complex shapes need to be bent and formed in the preparation process, and the cold bending property of the common low-alloy martensite wear-resistant steel cannot meet the requirements.

In order to improve the wear resistance of low-alloy steel plates, in recent years, Ti and V contents are increased in low-alloy wear-resistant steel in some steel mills at home and abroad, a martensite matrix is used for increasing the hardness of TiC and VC to precipitate and enhance the wear resistance, although the wear resistance is enhanced, the plasticity and toughness are poor, cold bending processing cannot be performed, and the low-alloy wear-resistant steel plates are difficult to popularize in a large scale.

Tianjin Lei Gong welding materials, Inc., Lewan Jun; chen Yang Rong; xulisxia; the invention discloses a high-wear-resistance bimetal composite wear-resistant plate, which is a Chinese patent document with the application publication number of CN103725976A, and relates to a high-wear-resistance bimetal composite wear-resistant plate, which comprises a low-carbon steel plate or a low-carbon alloy steel plate, wherein a wear-resistance alloy layer is welded on the low-carbon steel plate or the low-carbon alloy steel plate, and the high-wear-resistance bimetal composite wear-resistant plate is characterized in that: the wear-resistant alloy layer comprises the following components in percentage by mass: c: 0.35-0.55%; si: 2-2.4%; mn: 2.7-3.2%; cr: 11-12.5%; mo: 2.5-2.9%; v: 0.7-1.8%; w: 2.2-3.6%; b: 0.7 to 1.1 percent; the balance being iron. The invention has the advantages of ensuring the smooth surface of the wear-resisting plate and good wear resistance. The invention is the technological production of bimetal composite surfacing, the process is complex, the cost is high, and the steel plate can not be formed and processed due to the high hardness of the surfacing layer.

Baoshan steel works ltd, plum bin, yao lian, miao yuchuan and the like: CN103146997A patent document "a low-alloy high-toughness wear-resistant steel plate and its manufacturing method", relates to a low-alloy high-toughness wear-resistant steel plate and its manufacturing method, its chemical components (wt%) are: c: 0.08-0.20%, Si: 0.10-0.60%, Mn: 1.00-2.00%, B: 0.0005-0.0040%, Cr is less than or equal to 1.50%, Mo is less than or equal to 0.80%, Ni is less than or equal to 1.50%, Nb is less than or equal to 0.080%, V is less than or equal to 0.080%, Ti is less than or equal to 0.060%, Al: 0.010-0.080%, Ca: 0.0010 to 0.0080 percent, less than or equal to 0.0080 percent of N, less than or equal to 0.0080 percent of O, less than or equal to 0.0004 percent of H, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S, and the content of the elements meets the requirement that the content of (Cr/5+ Mn/6+50B) is less than or equal to 0.55 percent, the content of (Mo/3+ Ni/5+2Nb) is less than or equal to 0.45 percent, the content of (Al + Ti) is less than or equal to 0.01 percent, and the balance of Fe and inevitable impurities. The invention reduces the content of carbon and alloy elements, fully utilizes the characteristics of refining, strengthening and the like of micro-alloy elements such as Nb, Ti and the like, and adopts the TMCP process, so that the wear-resistant steel plate has the advantages of high strength and hardness, good toughness, easy welding and excellent wear resistance, and is suitable for easily worn parts in various mechanical equipment. The mechanical properties are as follows: the tensile strength is more than 1200MPa, the elongation is more than 12 percent, the Brinell hardness is more than 400HB, and the Charpy V-shaped longitudinal impact energy at-40 ℃ is more than 60J. The invention has higher strength, shaping, welding and other properties, but the wear resistance is equivalent to that of common martensite wear-resistant steel with the same hardness.

The published (bulletin) numbers of Jiangyin Xingsheng Cheng Special iron and Steel Co, Liujun, Li nationality, xu hong, etc.: CN111996441A patent document "a TiC enhanced martensite wear-resistant steel plate with good high toughness and bending property and its manufacturing method", relates to a TiC enhanced martensite wear-resistant steel plate with good high toughness and bending property and its manufacturing method, the element content: c: 0.18-0.30%, Si: less than or equal to 0.30 percent, Mn: 0.60-1.20%, Ti: 0.20-0.40%, Al: 0.04-0.08%, Ni: less than or equal to 0.10 percent, Cu: less than or equal to 0.10 percent, Cr: 0.20 to 1.00%, Mo: 0.10-0.60%, B: 0.0010-0.0040%, Ca: 0.001-0.005%, P: less than or equal to 0.015 percent, S: less than or equal to 0.003 percent, O: less than or equal to 0.0015 percent, N: less than or equal to 0.0030 percent, H: less than or equal to 0.0002 percent and the balance of Fe; C-Ti/4 is more than or equal to 0.13 and less than or equal to 0.25, so that the hardness of the TiC-formed martensite matrix reaches 400-480 HB; carbon equivalent CEV: less than or equal to 0.65 percent, and the machining welding performance can meet the manufacturing requirement of high-wear-resistance equipment. The process flow is as follows: converter or electric furnace steelmaking- > LF refining- > vacuum degassing- > Ca treatment- > continuous casting- > heating- > hot rolling- > quenching- > low-temperature tempering. The elongation A50 is more than or equal to 8 percent; low-temperature impact toughness: akv is more than or equal to 20J at minus 40 ℃, and the cold bending performance of the steel plate is as follows: and d is 5a, cold bending is performed for 90 degrees, and cracking is avoided. The wear resistance reaches 1.4 times and above of NM450 of the low-alloy martensite wear-resistant steel. The steel plate prepared by the method has good machining performance, and the hardness can reach HBW 400-480. The invention has good forming performance, but high Ti content and difficult smelting and continuous casting.

Jeffy iron and Steel works, Teze you, McJUSH; high mountain straight trees; d, the forest is moderate; japanese patent document of long valley and bang, application publication No. CN109072367A, "abrasion resistant steel sheet and method for manufacturing abrasion resistant steel sheet" discloses a steel sheet having a composition and a structure containing, in mass%: c: 0.10 to 0.23%, Si: 0.01 to 1.0%, Mn: 0.30-3.00%, P: 0.025% or less, S: 0.02% or less, Cr: 0.01-2.00%, Al: 0.001 to 0.100%, and N: 0.01% or less, and the balance of Fe and unavoidable impurities, wherein the volume fraction of martensite in the structure at a depth of 1mm from the surface of the wear-resistant steel sheet is 90% or more, the prior austenite grain diameter of the central portion of the wear-resistant steel sheet in the thickness thereof is 80 [ mu ] m or less, and the hardness at a depth of 1mm from the surface of the wear-resistant steel sheet is 360 to 490HBW 10/3000 in terms of Brinell hardness. The steel plate has complex alloy components, high cost and only has common wear resistance.

It can be seen that the existing HB400 wear-resistant steel plate has the following defects:

1. the components and the process are complex, and heterogeneous compounding or surfacing is needed;

2. smelting and continuous casting are difficult;

3. the cold bending forming cannot be carried out;

4. the wear resistance is insufficient.

Disclosure of Invention

The invention aims to provide an HB400 grade high wear-resistant cold-bending steel plate and a production method thereof, and the invention adopts a new wear-resistant concept on the basis of low-alloy wear-resistant steel, reasonably increases the Nb content in the steel, enhances the wear resistance by utilizing dispersed and precipitated high-hardness niobium carbide particles, and has the wear resistance which is more than 1.4 times of that of a common wear-resistant steel plate with the same hardness. The unique smelting, rolling and heat treatment production process is adopted to perform crack arrest treatment for forming a partial decarburized layer on the surface of the steel plate, and reasonable residual austenite content control is added to produce the high-wear-resistance low-alloy wear-resistant steel with Brinell hardness of 400HB, good plasticity and toughness and capable of being subjected to cold bending processing.

In order to realize the purpose, the invention adopts the following technical scheme:

an HB400 grade high wear-resistant cold-bending steel plate comprises the following chemical components in percentage by weight: 0.14 to 0.18 percent of C, 1.1 to 1.50 percent of Si, 0.7 to 1.0 percent of Mn, 0.12 to 0.20 percent of Nb, 0.15 to 0.35 percent of Cr, 0.4 to 0.6 percent of Ni0.040 to 0.060 percent of Al, less than or equal to 0.012 percent of P, less than or equal to 0.002 percent of S, less than or equal to 0.0030 percent of N, less than or equal to 0.00015 percent of H and less than or equal to 0.0015 percent of O; the balance of Fe and inevitable impurities; and C is not more than 0.0004 percent of Nb, and not more than 1.5 percent of Si and Ni is not more than 2.0 percent.

The steel plate has the main characteristic of chemical component design of microalloying of carbon, niobium and silicon, has relatively low alloy content, and is convenient for smelting and continuous casting. And performing low-temperature tempering heat treatment after continuous casting, controlled rolling and controlled cooling to obtain the HB400 steel plate with good ductility, toughness and wear resistance.

The reason for designing the elements of the invention is as follows:

c: in order to ensure high strength and hardness of the steel plate and stabilize the amount of retained austenite in the steel, a considerable amount of carbon is required for the purpose. Meanwhile, carbon can form carbide precipitation with Nb, and the wear resistance is improved. If the carbon content is too high, the welding performance is reduced, the solid solution and precipitation of Nb in the steel are also influenced, and in order to ensure that the steel plate has high wear resistance, good welding performance, forming performance and wear resistance, the content of C in the invention is controlled to be 0.14-0.18 percent, and simultaneously C is less than or equal to 0.03 percent;

si: the invention mainly adds elements. Is a non-carbide forming element, mainly has the functions of inhibiting the precipitation of carbide, stabilizing the content of residual austenite in steel, being beneficial to improving the low-temperature toughness and plasticity of the steel plate and ensuring good cold bending capability. Meanwhile, the thickness of the decarburized layer is stabilized, but the welding performance is reduced when the Si content is excessive, so that the Si content is controlled to be 1.1-1.5 percent;

mn: the main function is to improve hardenability and promote solid solution of Nb. The strength and the wear resistance are improved, but the center segregation is easy to form when the content is too high, so that the center of the plate blank is prone to crack; the method is not beneficial to cold forming, so the Mn content is controlled to be 0.7-1.0 percent;

nb: the invention is an important additive element. The main functions are as follows: increasing the wear resistance and plasticity. Nb is a strong carbon and nitrogen compound-forming element, and is combined with C, N in steel to form compounds such as NbC and Nb (C, N). The steel has the characteristics of high chemical stability and high hardness, can form 1.4 times of wear resistance of common wear-resistant steel, and has the effects of increasing hardenability and precipitation strengthening by adding Nb element to ensure that a large amount of carbonitride is precipitated by strain induction in the rolling process of a low-temperature austenite structure; nb dissolved in austenite suppresses austenite recrystallization and refines austenite grains in the two-stage rolling process. Is beneficial to the cold bending performance of the steel plate. However, too high Nb content affects the mechanical properties of the steel sheet. Therefore, the addition amount of Nb in the invention is 0.12-0.20%.

Ni: the non-carbide forming elements, which mainly serve to improve toughness and plasticity of the steel, do not achieve the desired effect if the Ni content is less than 0.4%, while if the Ni content is greater than 0.6%, the cost is too high and the retained austenite may be too much during quenching. The invention controls the Ni: 0.4-0.6%, because Si and Ni have the function of promoting the content of the retained austenite, the content of the retained austenite is controlled to be 5-10%, and the total content of Si and Ni is controlled to prevent the content of the retained austenite from being too much or too little, so that the content of Si and Ni is more than or equal to 1.5% and less than or equal to 2.0%.

Al: effective elements for deoxidation and nitrogen fixation. Can reduce oxide inclusions in steel and purify the steel, is favorable for improving the formability of a steel plate, causes difficult casting due to overhigh content and can form a large amount of Al in the steel ₂ O ₃ Inclusions, resulting in poor ductility, and nitrogen fixation ensure that niobium is mainly combined with carbon. Therefore, in the present invention, Al: 0.04 to 0.06 percent.

Cr: the hardenability of the steel is increased. Chromium is a strong carbide former and may provide increased strength and hardness. Excessive addition of Cr affects weldability, so that the present invention controls Cr: 0.15 to 0.35 percent.

Impurity elements: in order to ensure that the steel plate has good plasticity and toughness and avoid the occurrence of cracks during abrasion and cold bending, the invention controls P to be less than or equal to 0.012 percent, S to be less than or equal to 0.002 percent, H to be less than or equal to 0.00015 percent and O to be less than or equal to 0.0015 percent.

The content of the retained austenite in the steel is 5-10%, and the thickness of the surface decarburized layer of the steel plate is 1-2 mm.

Under the same experimental conditions, the wear resistance of the steel plate reaches more than 1.4 times of that of the steel plate with the same hardness NM400, and the cold-bending D of 180 degrees is 3 a.

A production method of an HB400 grade high wear-resistant cold-bending steel plate comprises the following production process flows: smelting → refining → continuous slab casting → heating and slow cooling of casting blank → heating → controlled rolling → controlled cooling → tempering heat treatment, comprising the following steps:

1) smelting: the invention controls the RH degassing time during refining, the RH vacuum cycle time is more than or equal to 15min, and the [ N ] of the molten steel is less than or equal to 0.0030%, the [ O ] is less than or equal to 0.0015% and the [ H ] is less than or equal to 0.00015% through long-time vacuum treatment. The continuous casting is characterized in that: properly increasing the cooling speed of the secondary cooling area of continuous casting, adopting a medium cooling intensity mode, controlling the water supply amount of the secondary cooling area of the continuous casting to be 60-80%, and controlling the drawing speed of the continuous casting billet to be 1.1-1.5 m/min; the aim is to avoid excessive precipitation of coarse niobium carbides in the high-temperature zone. The thickness of the casting blank is 200-250 mm, and electromagnetic stirring or soft reduction is adopted during continuous casting to reduce center segregation. The invention controls the center segregation to be less than or equal to B0.5 and the middle crack to be less than or equal to 0.5 grade, and aims to ensure that the internal defects of the steel plate are the lowest during cold bending. After continuous casting, heating the casting blank to 550-650 ℃, and slowly cooling the casting blank along with the furnace for not less than 48 hours; the hydrogen content in the steel billet can be effectively removed, and the slow cooling at about 600 ℃ is beneficial to fully separating out the niobium fine carbide.

2) Rolling: heating the soaking section in oxidizing atmosphere at 1250-1310 ℃ for not less than 2.5 hours; higher heating temperature and longer holding time aims: 1) ensuring that higher niobium can be fully dissolved; 2) the homogenization of the center segregation elements is facilitated; 3) the formation of a 1-2 mm decarburized layer on the surface after rolling is facilitated, and the cold bending performance of the rolled steel plate can be effectively improved.

During rolling, two stages of controlled rolling, namely rough rolling and finish rolling, are adopted, and the purpose is to fully refine and homogenize the hot rolling structure. The rolling start temperature in the rough rolling stage is more than or equal to 1100 ℃, the finish rolling temperature is controlled to be more than or equal to 1050 ℃, and the single-pass reduction rate of rough rolling is not lower than 15%; ensuring the deep penetration of the rolling force and promoting the precipitation of niobium carbide; the finish rolling initial rolling temperature is 970-1030 ℃, the deformation rate is not lower than 70%, the aim is to crush coarse niobium carbide and improve the core defect structure, and the finish rolling temperature is 900-950 ℃.

After rolling, water cooling is carried out, and ultrafast cooling and laminar cooling are adopted, wherein the water inlet temperature of the ultrafast cooling is 870-920 ℃, the ultrafast cooling speed is more than or equal to 20 ℃/s, and the final cooling temperature of the ultrafast cooling is 600-650 ℃; laminar cooling speed is 5-10 ℃/s, red return temperature is 200-250 ℃, and air cooling is carried out to room temperature.

The front section adopts ultra-fast cooling, the temperature of water entering the ultra-fast cooling is 870-920 ℃, the ultra-fast cooling speed is more than or equal to 20 ℃/s, and the ultra-fast cooling final cooling temperature is 600-650 ℃; can reduce the aggregation of niobium carbonitride in the grain boundary during slow cooling, and simultaneously refine austenite grains, which is beneficial to plasticity and toughness and wear resistance. Laminar cooling is adopted in the rear section, the cooling speed is 5-10 ℃/s, the temperature of red return is 200-250 ℃, and air cooling is carried out to the room temperature; the weak cooling and the controlled cooling of the rear section are higher than 200 ℃, so that the internal stress of the steel plate can be reduced, the content of a small amount of residual austenite is reserved, and the plate flatness below 5 mm/m and the cold bending performance are ensured.

3) And (3) heat treatment: the tempering temperature is 200-250 ℃, and the tempering heat preservation time is 8-12 min/mm. The invention adopts tempering time which is higher than the conventional tempering time (3-5 min/mm), and aims to fully remove quenching internal stress, improve the plasticity of the steel plate and ensure the cold forming performance of the steel plate.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a HB400 grade high wear-resistant cold-roll-formable steel plate with the thickness of 10-30 mm and a production method thereof.

1. Continuous casting production can be carried out;

2. the surface hardness is more than HB400, and AKV is more than or equal to 40J at the temperature of minus 40 ℃;

3. the wear resistance is more than 1.4 times of that of the low-alloy wear-resistant steel plate with the same hardness;

4. the product has good cold forming performance and is qualified when the cold bending D of 180 degrees is 3 a.

Detailed Description

The following embodiments are further illustrated by reference to the following specific examples:

according to the chemical components and the production process of the invention, the actual chemical components of the steel of the invention are shown in table 1, the smelting process is shown in table 2, the actual rolling process parameters of the steel of the invention are shown in table 3, the controlled cooling process is shown in table 4, the heat treatment process parameters are shown in table 5, the physical property test results of the invention are shown in table 6, and the wear resistance test results are shown in table 7.

TABLE 1 examples of the metallurgical composition of the steel grades according to the invention, wt.%

Serial number	C	Si	Mn	Nb	Cr	Ni	Al	P	S	H	0	N	Si+Ni	C*Nb
															1	0.14	1.5	1.0	0.12	0.35	0.40	0.040	0.009	0.0013	0.00012	0.0014	0.0030	1.90	0.00017
2	0.15	1.3	0.9	0.14	0.25	0.50	0.045	0.011	0.014	0.00014	0.0015	0.0022	1.82	0.00021
															3	0.17	1.2	0.8	0.17	0.25	0.55	0.052	0.008	0.016	0.00015	0.0011	0.0025	1.75	0.00029
4	0.18	1.1	0.7	0.20	0.15	0.60	0.055	0.010	0.016	0.00008	0.0009	0.0020	1.72	0.00036

TABLE 2 smelting process of steel grades of the present invention

TABLE 3 actual Rolling Process parameters for inventive Steel examples

TABLE 4 actual controlled Cooling Process parameters for inventive Steel examples

TABLE 5 Heat treatment Process for inventive Steel examples

TABLE 6 mechanical Properties of inventive Steel examples

The comparison experiment of the high wear-resistant steel plate and the common NM400 steel plate is carried out in an MLS-225 type wet sand rubber wheel type wear testing machine, the applied pressure is 70N, and the rotating speed of a grinding wheel is as follows: 200r/min, total revolutions: 2000r, test time about 10 minutes. The results are shown in Table 7.

TABLE 7 comparative abrasion resistance of inventive examples

Steel grade	Abrasion loss DeltaM/g	Comparison of abrasion resistance
			Normal NM400	0.06500	1.00
1-1	0.04452	1.46
			1-2	0.04392	1.48
2-1	0.04483	1.45
			2-2	0.04545	1.43
3-1	0.04610	1.41
			3-2	0.04545	1.43
4-1	0.04483	1.45
			4-2	0.04392	1.48

It can be seen that the wear resistance of the steel plate of the invention reaches more than 1.4 times of the NM400 of the common wear-resistant steel plate.

Claims

1. An HB400 grade high wear-resistant cold-bending steel plate is characterized in that the steel comprises the following chemical components in percentage by weight: 0.14 to 0.18 percent of C, 1.1 to 1.50 percent of Si, 0.7 to 1.0 percent of Mn, 0.12 to 0.20 percent of Nb, 0.15 to 0.35 percent of Cr, 0.4 to 0.6 percent of Ni, 0.040 to 0.060 percent of Al, less than or equal to 0.012 percent of P, less than or equal to 0.002 percent of S, less than or equal to 0.0030 percent of N, less than or equal to 0.00015 percent of H and less than or equal to 0.0015 percent of O; the balance of Fe and inevitable impurities; and C is not more than 0.0004 percent of Nb, and not more than 1.5 percent of Si and Ni is not more than 2.0 percent.

2. The HB400 grade high wear resistance cold-bending steel plate according to claim 1, wherein the steel contains 5% -10% of residual austenite, and the decarburized layer on the surface of the steel plate is 1-2 mm thick.

3. The HB400 grade high wear resistant cold-bendable steel plate according to claim 1, characterized in that the wear resistance of the steel plate reaches more than 1.4 times of the same hardness NM400 steel plate under the same experimental conditions, and the cold formability is 180 ° cold bending D-3 a.

4. A method for producing a HB400 grade high wear resistant cold-bendable steel sheet as claimed in any one of claims 1 to 3, characterized by comprising the steps of:

1) smelting: the RH vacuum circulation time is more than or equal to 15min, and the casting speed of the continuous casting billet is controlled to be 1.1-1.5 m/min; the water supply amount of the continuous casting secondary cooling area accounts for 60-80%, the center segregation of the billet is less than or equal to B0.5, the center crack is less than or equal to 0.5 level, the casting blank is heated to 550-650 ℃ after continuous casting, and furnace slow cooling is carried out for not less than 48 hours;

2) rolling: heating the soaking section in oxidizing atmosphere at 1250-1310 ℃ for not less than 2.5 hours;

during rolling, controlled rolling is carried out in two stages of rough rolling and finish rolling, the rolling start temperature in the rough rolling stage is more than or equal to 1100 ℃, the finish rolling temperature is controlled to be more than or equal to 1050 ℃, and the single-pass reduction rate of the rough rolling is not lower than 15%; the finish rolling start temperature is 970-1030 ℃, the deformation rate is not lower than 70%, and the finish rolling temperature is 900-950 ℃;

after rolling, water cooling is carried out, and ultrafast cooling and laminar cooling are adopted, wherein the water inlet temperature of the ultrafast cooling is 870-920 ℃, the ultrafast cooling speed is more than or equal to 20 ℃/s, and the final cooling temperature of the ultrafast cooling is 600-650 ℃; laminar cooling speed is 5-10 ℃/s, the temperature of red return is 200-250 ℃, and air cooling is carried out to room temperature;

3) and (3) heat treatment: the tempering temperature is 200-250 ℃, and the tempering heat preservation time is 8-12 min/mm.