CN114959424A - Production method of anti-deformation wear-resistant steel - Google Patents

Abstract

The invention relates to a method for producing anti-deformation wear-resistant steel, which comprises the following chemical compositions of C = 0.18-0.23%, Si = 0.50-0.80%, Mn = 1.0-1.50%, P is less than or equal to 0.012%, S is less than or equal to 0.003%, Ti = 0.010-0.025%, Als = 0.060-0.10%, Cr = 0.40-1.0%, Mo = 0.10-0.30%, B = 0.0008-0.0025%, CEV is less than or equal to 0.65%, and the balance is Fe and other trace elements; the process comprises the following steps: molten iron pretreatment → converter smelting → LF external refining → VD vacuum treatment → continuous casting → heating → rolling → straightening → quenching → tempering → finishing → performance test → flaw detection. The produced wear-resistant steel plate with the thickness specification of 6-30mm has the steel plate yield strength of more than or equal to 1200MPa, the tensile strength of more than or equal to 1400MPa, the elongation of more than or equal to 13 percent, the surface hardness of 420-470HB and the transverse impact at minus 40 ℃ of more than or equal to 40J.

Description

Production method of anti-deformation wear-resistant steel

Technical Field

The invention belongs to the technical field of steel making, and relates to a production method of anti-deformation wear-resistant steel.

Background

The development and application of low-alloy wear-resistant steel with weldability and machinability are rapidly developed. The steel has better obdurability and wear resistance, simple production process and reasonable comprehensive economy, and is popular with users. The low-alloy high-strength wear-resistant steel is widely applied to mining machinery, coal mining and transportation, agricultural machinery, building materials, electric machinery, railway transportation and the like, so as to meet the use requirements of large machinery on high wear resistance, long service life and simple cold forming when the large machinery works in severe environment. At present, most of the development and research of wear-resistant steel focuses on improving the wear resistance of materials, and in the application working condition of the wear-resistant steel, the abrasive wear is a main wear mode, the wear resistance is generally improved by improving the toughness and the hardness, and the service life is greatly prolonged. The wear-resistant steel equipment often faces the deformation problem when in use, for example, when the ore is loaded and transported in a mine car carriage, the carriage bears the smashing and pressing of large ore blocks, the local deformation of a steel plate is easy to generate and serious, the operation efficiency and the service life of the carriage are influenced, and great difficulty is brought to subsequent maintenance.

CN201510962051.7 discloses a martensite-ferrite dual-phase wear-resistant steel plate and a preparation method thereof, and the method is characterized in that quenching is carried out between Ac 1-Ac 3, so that ferrite soft phase is introduced to improve the toughness of the wear-resistant steel. CNCN201711221709.4 discloses "a wear-resistant steel plate for mining machinery", which is a steel plate with wear resistance improved by passivating the surface of the wear-resistant steel plate. CN201310322344.X discloses a wear-resistant steel plate with low crack sensitivity index and high strength and a preparation method thereof, Pcm is reduced by reducing the contents of Mn, Cr and Mo, the performance index of the wear-resistant steel plate meets 450HB, and the toughness is not related. CN200910045273.7 discloses "a high-toughness wear-resistant steel plate and a manufacturing method thereof", which utilizes low-carbon components to improve the low-temperature toughness of the wear-resistant steel plate, and the hardness level is NM 360.

The above patents are mainly concerned with improvement of wear resistance and weldability, but do not relate to deformation resistance of wear-resistant steel sheets.

Disclosure of Invention

The invention aims to provide a production method of anti-deformation wear-resistant steel, wherein the thickness of the produced wear-resistant steel plate is 6-30mm, the yield strength of the steel plate is more than or equal to 1200MPa, the tensile strength is more than or equal to 1400MPa, the elongation is more than or equal to 13%, and the surface hardness is 420-470HB and the transverse impact at minus 40 ℃ is more than or equal to 40J.

The technical scheme of the invention is as follows:

the production process of the anti-deformation wear-resistant steel includes molten iron pretreatment → converter smelting → LF external refining → VD vacuum treatment → continuous casting → heating → rolling → straightening → quenching → tempering → finishing → performance inspection → flaw detection. The chemical composition percentage content of the steel is C =0.18% -0.23%, Si =0.50% -0.80%, Mn =1.0% -1.50%, P is less than or equal to 0.012%, S is less than or equal to 0.003%, Ti =0.010% -0.025%, Als =0.060% -0.10%, Cr =0.40% -1.0%, Mo =0.10% -0.30%, B =0.0008% -0.0025%, CEV is less than or equal to 0.65%, and the balance is Fe and other trace elements; the key process steps comprise:

(1) heating and discharging the plate blank at 1100-1150 ℃ for 30-50 minutes; the rough rolling reduction rate of three passes is more than or equal to 18 percent, and the reduction rate of at least one pass is more than or equal to 22 percent; when the target thickness is 20mm or below, the thickness of the intermediate blank is 70mm, when the target thickness is more than 20mm, the thickness of the intermediate blank is 3.5 times of the thickness of a finished product, the reduction rate of the secondary finish rolling pass is more than or equal to 20%, and the finish rolling temperature Tnr + (0-30) DEG C;

(2) and (3) quenching and tempering: the quenching temperature is 860-890 ℃, and the heating time is (plate thickness multiplied by 2+ 10) min when the plate thickness is less than 20 mm; when the plate thickness is more than or equal to 20mm, the heating time is multiplied by 2.5 min; tempering at 170-220 deg.C for 6 min.

The steel plate with the structure mainly comprising tempered martensite is produced by the method, the yield strength is more than 1200MPa, the tensile strength is more than 1400MPa, the elongation is more than 13%, the surface hardness is 420-470HB, and the transverse Charpy impact energy at minus 40 ℃ reaches more than 40J.

The principle of the invention is as follows:

(1) designing chemical components: the content of C is increased, which is beneficial to improving the hardenability and the strength of the steel, the C is the most effective and cheap element for improving the yield strength of the steel, when the carbon content exceeds 0.23 percent, the welding performance of the steel is deteriorated, and the content of C is designed to be 0.18 to 0.23 percent according to the hardness and the strength requirements of the product. Si exists in ferrite or austenite in a solid solution state, so that the elastic limit, the yield strength, the fatigue strength and the wear resistance of the steel are obviously improved, the hardness and the strength of the ferrite and the austenite are improved, and the effect is stronger than that of Mn, Ni, Cr, Mo, V and the like, and 0.50-0.80% of Si is added in the invention. In order to meet the requirement of steel performance indexes on hardenability, Cr and Mo are added to improve the hardenability and strength, but the high addition amount can cause high carbon equivalent to influence weldability, and in order to avoid the adverse effect, a small amount of B is required to be added to improve the hardenability. BN generated by the reaction of nitrogen and boron in the steel can be partially gathered at a crystal boundary to promote the generation of ferrite and cause adverse effect on hardenability, the corresponding addition of Ti and Al is calculated according to the control level of the nitrogen content in the steel at present, the condition that the excessive N causes the reduction of effective boron is avoided, and fine TiN and AlN particles are used for refining grains. As the content of the added carbon is 0.18-0.23%, the Nb solubility is reduced, and meanwhile, 0.50-0.80% of Si is added, the non-recrystallization temperature is greatly reduced, and the rolling process is in a recrystallization zone for rolling, so that the addition of Nb element is not needed.

(2) The rolling process comprises the following steps: the heating process of the plate blank is determined according to the required solid solution temperature of the designed alloy element, the designed alloy element does not contain Nb, and the alloy solid solution temperature is relatively low; meanwhile, the heating temperature is high, austenite grains grow large, the yield strength is not favorably improved, and in order to obtain the size of fine original austenite grains, the heating temperature is controlled to be 1100-1150 ℃. The rolling process adopts low-temperature recrystallization zone rolling, the low-temperature condition is favorable for delaying the recovery and growth of a recrystallized structure, and the recrystallization of the structure can be ensured to refine grains by a larger reduction rate under the low-temperature condition.

(3) The heat treatment process comprises the following steps: the austenitizing temperature and the heat preservation time influence the solid solution of alloy elements in the material, and influence the hardenability and the grain size, in order to ensure that the alloy elements are fully dissolved in the solid solution and the grains are not excessively grown, the material is heated at the temperature of AC3+ (10-40) DEG C, and the heating time is 3 times of the thickness of the plate.

According to the invention, through reasonable chemical composition, rolling process and heat treatment process design, the 6-30mm deformation-resistant wear-resistant steel is obtained, the performance index meets the standard requirement, and the steel plate flatness meets the high-standard requirement of downstream enterprises. The invention has the advantages that: (1) the low-carbon equivalent alloy component design improves the yield strength of steel through C, Si and other elements, improves the hardenability by utilizing Cr and B, reduces the addition of Mo, Ni and other precious alloys, and has less precious alloy addition and low alloy cost; (2) the rolling adopts recrystallization zone rolling, so that the performance anisotropy of the steel plate is reduced; (3) the grain size is small, and the low-temperature impact toughness is good; (4) the steel plate has high yield strength, is not easy to deform, and prolongs the service life of the product.

Detailed Description

The present invention will be further described with reference to the following examples. The steel sheets produced in the respective examples were examined for properties after heat treatment as shown in Table 1.

Example 1: production of 6mm thick steel plate

The chemical composition of the steel comprises, by mass, C =0.18%, Si =0.55%, Mn =1.05%, P =0.010%, S =0.002%, Ti =0.015%, Als =0.072%, Cr =0.45%, Mo =0.16%, B =0.0015%, CEV =0.47%, and the balance of Fe and other trace elements; the process comprises the following steps:

(1) carrying out continuous casting on the molten steel subjected to converter smelting, LF refining and vacuum treatment to obtain a qualified plate blank;

(2) heating the plate blank to a tapping temperature of 1120 ℃, and soaking for 37 minutes; the three-pass reduction rate after rough rolling is respectively 18.5%, 20.3% and 22.5%; the thickness of the intermediate billet is 70mm, the reduction rate of the finish rolling in three passes is more than or equal to 20 percent, the reduction rate is respectively 20.3 percent, 21.2 percent and 22.6 percent, and the final rolling temperature is 803-832 ℃;

(3) after rolling, rapidly cooling the steel plate to 705-738 ℃ through Mulpic;

(4) and (3) quenching and tempering: quenching temperature is 870 ℃, and heating time is 22 min; tempering at 170 deg.C for 36 min.

Example 2: production of 15mm thick steel plate

The chemical composition of the steel comprises, by mass, C =0.19%, Si =0.62%, Mn =1.15%, P =0.009%, S =0.0016%, Ti =0.017%, Als =0.075%, Cr =0.63%, Mo =0.19%, B =0.0017%, CEV =0.55%, and the balance of Fe and other trace elements; the process comprises the following steps:

(1) carrying out continuous casting on the molten steel subjected to converter smelting, LF refining and vacuum treatment to obtain a qualified plate blank;

(2) heating the plate blank to the tapping temperature of 1133 ℃, and soaking for 35 minutes; the three-pass reduction rate after rough rolling is respectively 18.9%, 19.5% and 22.7%; the thickness of the intermediate blank is 70mm, the reduction rate of the finish rolling in three passes is more than or equal to 20%, the reduction rate is respectively 20.2%, 20.7% and 21.6%, and the final rolling temperature is 811-839 ℃;

(3) after rolling is finished, rapidly cooling the steel plate to 717-745 ℃ through Mulpic;

(4) and (3) hardening and tempering: quenching temperature of 860 deg.C, and heating time of 40 min; tempering at 170 deg.C for 90 min.

Example 3: production of 30mm thick steel plate

The chemical composition of the steel is, by mass, C =0.21%, Si =0.70%, Mn =1.25%, P =0.009%, S =0.0012%, Ti =0.016%, Als =0.082%, Cr =0.71%, Mo =0.25%, B =0.0017%, CEV =0.61%, and the balance being Fe and other trace elements; the process comprises the following steps:

(1) carrying out continuous casting on the molten steel subjected to converter smelting, LF refining and vacuum treatment to obtain a qualified plate blank;

(2) heating the plate blank to the tapping temperature of 1138 ℃, and soaking for 40 minutes; the three-pass reduction rate after rough rolling is respectively 19.1%, 19.6% and 22.3%; the thickness of the intermediate blank is 105mm, the reduction rate of the finish rolling in three passes is more than or equal to 20%, the reduction rate is respectively 20.2%, 20.7% and 21.6%, and the final rolling temperature is 813-845 ℃;

(3) after rolling is finished, rapidly cooling the steel plate to 710-746 ℃ through Mulpic;

(4) and (3) quenching and tempering: quenching temperature of 860 deg.C, and heating for 75 min; tempering at 170 deg.C for 180 min.

TABLE 1 test Properties of the steel sheets produced in the examples after Heat treatment

。

Claims (1)

1. The production process of the anti-deformation wear-resistant steel includes molten iron pretreatment → converter smelting → LF external refining → VD vacuum treatment → continuous casting → heating → rolling → straightening → quenching → tempering → finishing → performance test → fault detection, and is characterized in that: the chemical composition percentage content of the steel is C =0.18% -0.23%, Si =0.50% -0.80%, Mn =1.0% -1.50%, P is less than or equal to 0.012%, S is less than or equal to 0.003%, Ti =0.010% -0.025%, Als =0.060% -0.10%, Cr =0.40% -1.0%, Mo =0.10% -0.30%, B =0.0008% -0.0025%, CEV is less than or equal to 0.65%, and the balance is Fe and other trace elements; the key process steps comprise:

(1) heating and discharging the plate blank at 1100-1150 ℃ for 30-50 minutes; the rough rolling reduction rate of three passes is more than or equal to 18 percent, and the reduction rate of at least one pass is more than or equal to 22 percent; when the target thickness is 20mm or below, the thickness of the intermediate blank is 70mm, when the target thickness is more than 20mm, the thickness of the intermediate blank is 3.5 times of the thickness of a finished product, the reduction rate of the secondary finish rolling pass is more than or equal to 20%, and the finish rolling temperature Tnr + (0-30) DEG C;

(2) and (3) quenching and tempering: the quenching temperature is 860-890 ℃, and the heating time is (plate thickness multiplied by 2+ 10) min when the plate thickness is less than 20 mm; when the plate thickness is more than or equal to 20mm, the heating time is multiplied by 2.5 min; tempering at 170-220 deg.C for 6 min.