Alkali coal water corrosion resistant wear-resistant steel and preparation method thereof

Abstract

The invention discloses an alkaline coal-water corrosion-resistant wear-resistant steel and a preparation method thereof. By reasonably adding elements such as Cr, Cu, Ni, and Sb, the self-corrosion potential and hardness a of the steel plate are improved, and at the same time, a wear-resistant steel with a structure of lower bainite + martensite + retained austenite is obtained; and through process design, the occurrence of cracks in the Sb-containing wear-resistant steel during the production process is effectively suppressed, and a large amount of Ti precipitated phases are retained inside the structure as hydrogen traps, thereby reducing the risk of delayed cracking of the Sb-containing wear-resistant steel plate during use; and through the composite addition of Ti and Mo, in conjunction with a slow cooling process and a heat treatment process design, a large amount of Ti and Mo composite carbides are retained in the quenched steel plate, and these carbides serve as hydrogen traps, thereby greatly improving the hydrogen-induced crack resistance of the Sb-containing wear-resistant steel during service, and finally obtaining alkaline coal-water corrosion-resistant wear-resistant steel with excellent mechanical properties and resistance to hydrogen-induced cracks.

Description

Technical Field

[0001] The present invention relates to the field of metal materials, in particular to wear-resistant steel resistant to alkaline coal water corrosion and a preparation method thereof. Background Art

[0002] Low-alloy wear-resistant steel, with its excellent comprehensive properties, is widely used in mining, mineral processing, metallurgy, chemical engineering, and transportation. As a consumable material, its lifespan depends not only on the wear intensity of the operating conditions, but is also strongly affected by the corrosive environment of the operating conditions. Scraper conveyors are the primary equipment for coal mining and transportation. During their service underground in coal mines, they are subjected to high-intensity wear from coal, gangue, and other materials for long periods of time. The plates and bottom plates are primarily made of low-alloy wear-resistant steel. At the same time, the corrosion caused by coal mine water on the wear-resistant steel is extremely severe, which can change the service conditions of the wear-resistant steel from a single wear condition to a corrosive wear condition, exacerbating the wear of the wear-resistant steel. Therefore, it is necessary to develop corrosion-resistant and wear-resistant steel plates specifically for the mining environment, reduce the loss of wear-resistant steel, and extend the service life of wear-resistant steel and related equipment.

[0003] Publication No. CN114774772A discloses a corrosion-resistant 500HB martensitic wear-resistant steel plate. Although the corrosion resistance of the wear-resistant steel plate is significantly enhanced, the alloy cost is high due to the addition of a large amount of Ni, Cr and Mo elements.

[0004] Publication number CN110387507B discloses an HB500-grade wear-resistant steel for corrosive slurry transport containers. The patent document does not confirm the corrosion or abrasion resistance through experiments, and its manufacturing process includes online quenching, cooling from no less than 825°C to room temperature at a cooling rate of 55-65°C / s. This process is not conducive to controlling internal cracks in high-grade wear-resistant steel plates.

[0005] Publication No. CN112267073A discloses a corrosion-resistant wear steel plate with excellent low-temperature toughness and welding performance. The corrosion resistance of the steel is enhanced by adding Sb and Sn elements, but it does not take into account that Sb and Sn elements will also increase the risk of cracking in the wear-resistant steel. In addition, there is no corresponding technology to alleviate or avoid the negative effects of Sb and Sn elements on cracking in the wear-resistant steel. At the same time, the corrosion resistance or wear resistance effect has not been clarified through experiments.

[0006] Publication No. CN113106341B discloses a high-strength, tough, weldable, corrosion-resistant, and wear-resistant steel plate with a controlled composition of Mo / Ti: 1.8% to 7.0, and Ti / Als: 3 to 13. Similarly, this patent does not confirm the corrosion or wear resistance effects through experiments, and its manufacturing process includes online quenching, cooling from 820 to 860°C to 220 to 320°C at a cooling rate of 35 to 50°C / s. This process is not conducive to controlling internal cracks in high-grade wear-resistant steel plates.

[0007] It can be seen that there is still no mature technical solution for the use of wear-resistant steel in alkaline coal mine water service conditions. Summary of the Invention

[0008] In view of this, the present disclosure provides a preparation method of alkaline coal-water corrosion-resistant wear-resistant steel, which can not only improve the corrosion and wear resistance of the wear-resistant steel under alkaline coal-water working conditions, but also ensure that the steel plate does not crack during the manufacturing process and has a strong ability to resist delayed cracks during service.

[0009] In addition, the present disclosure also provides wear-resistant steel produced by the above-mentioned production method.

[0010] In a first aspect, the preparation method of the wear-resistant steel resistant to alkaline coal water corrosion comprises the following steps: the alloying elements of the wear-resistant steel are set to the following percentage by weight:

[0011] C: 0.24% ~ 0.40%, Si: 1.10% ~ 1.70%, Mn: 1.20% ~ 1.80%, P: ≤ 0.015%, S: ≤ 0.003%, Cr: 1.10% ~ 1.70%, Cu: 0.10% ~ 0.40%, Ni: 0.10% ~ 0.40%, Mo: 0.10% ~ 0.55%, Sb: 0.06% ~ 0.10%, Ti: 0.10% ~ 0.18%, Als: 0.015% ~ 0.05%, B: 0.0008% ~ 0.0016%, the balance is Fe and unavoidable impurities.

[0012] In the present disclosure and possible embodiments, the preparation method includes the steps of slow cooling and heating, rolling and heat treatment of continuous casting billets, wherein:

[0013] In the continuous casting billet slow cooling and heating process, the continuous casting billet is placed in a slow cooling pit or a heating furnace with a heating function for heating and slow cooling. When the slow cooling starts, the temperature of the continuous casting billet is ≥430°C. The continuous casting billet is kept at 500°C to 580°C for 24 hours to 36 hours. After that, the heating is stopped and the continuous casting billet is cooled in the slow cooling pit or the heating furnace for 24 hours to 36 hours.

[0014] After slow cooling, the continuous casting billet is sent to a heating furnace with an entry temperature of ≥300° C., a heating temperature of 1100° C. to 1200° C., and a time of the continuous casting billet in the furnace of 0.45 min / mm to 0.7 min / mm.

[0015] In the present disclosure and possible embodiments, during the rolling, a hot rolling method is adopted, the starting rolling temperature is 950°C to 1050°C, and the finishing rolling temperature is 900°C to 1050°C.

[0016] In the present disclosure and possible embodiments, in the slow cooling process, the steel plates are stacked and slowly cooled off the production line after rolling, with the temperature of the stacked and slowly cooled steel plates being 540°C ≤ 640°C, and cooled to ≤ 150°C.

[0017] In the present disclosure and possible embodiments, the heat treatment process is set to quenching treatment and tempering treatment, and the process of quenching and heating the steel plate in the quenching heat treatment furnace is divided into a high-temperature section and a cooling section; the temperature of the high-temperature section of the quenching heat treatment furnace is 840°C to 880°C, and the time of the high-temperature section in the furnace is 1.4 min / mm to 2.0 min / mm; the temperature of the cooling section is 740°C to 780°C, and the time of the cooling section in the furnace is 0.8 min / mm to 1.4 min / mm.

[0018] In the present disclosure and possible embodiments, the steel plate enters a roller quenching machine for quenching after exiting the quenching heat treatment furnace, the average cooling rate of quenching is 9°C to 52°C / s, and the final quenching temperature is 280°C to 380°C.

[0019] In the present disclosure and possible embodiments, after the quenching treatment, the steel plate is immediately placed in a tempering furnace, the furnace entry temperature of the steel plate is ≥180°C, the tempering heating temperature is 180°C to 240°C, and the tempering holding time is 4.0 min / mm to 6.0 min / mm.

[0020] In the second aspect, the alkaline coal water corrosion-resistant wear-resistant steel is prepared by the method of the first aspect.

[0021] The present invention has the following beneficial effects:

[0022] (1) The wear-resistant steel of the present invention improves the self-corrosion potential and hardness a of the steel plate by reasonably adding elements such as Cr, Cu, Ni, and Sb, effectively enhancing the wear-resistant steel's ability to resist corrosion in alkaline coal mine water. At the same time, a wear-resistant steel with a structure of lower bainite + martensite + retained austenite is obtained, thereby improving the corrosion and wear resistance of the wear-resistant steel under alkaline coal mine working conditions. The relative wear resistance is 1.18 to 1.35 times that of low-alloy wear-resistant steel of the same hardness level.

[0023] (2) The present invention effectively suppresses the problem of cracks in Sb-containing wear-resistant steel during the production process through process design, avoids the harm of Sb low-melting-point elements causing cracks in the steel plate, retains a large amount of Ti precipitate phase in the organization as a hydrogen trap, and reduces the risk of delayed cracks in the Sb-containing wear-resistant steel plate during use; and through the composite addition of Ti and Mo, combined with the slow cooling process and heat treatment process design, it is achieved that a large amount of Ti and Mo composite carbides are retained in the quenched steel plate, and used as hydrogen traps, greatly improving the ability of Sb-containing wear-resistant steel to resist hydrogen-induced cracks during service, and obtaining wear-resistant steel with excellent mechanical properties, resistance to hydrogen-induced cracks, and resistance to alkaline coal mine water corrosion. DETAILED DESCRIPTION

[0024] The present disclosure is described below based on examples, but it is worth noting that the present disclosure is not limited to these examples. In the detailed description of the present disclosure below, some specific details are described in detail. However, for the parts that are not described in detail, those skilled in the art can also fully understand the present disclosure. At the same time, unless the context clearly requires otherwise, the words "including", "comprising" and similar words throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, as "including but not limited to".

[0025] The present disclosure describes in detail the alkaline coal water corrosion resistant wear-resistant steel and its preparation method through Examples 1-15, wherein the alloying elements constituting the alkaline coal water corrosion resistant wear-resistant steel are respectively as follows in terms of weight percentage:

[0026] C: 0.24~0.40%, Si: 1.10~1.70%, Mn: 1.20~1.80%, P: ≤0.015%, S: ≤0.003%, Cr: 1.10~1.70%, Cu: 0.10~0.40%, Ni: 0.10~0.40%, Mo: 0.10~0.55%, Sb: 0.06~0.10%, Ti: 0.10-0.18%, Als: 0.015-0.05%, B: 0.0008~0.0016%, the balance is Fe and unavoidable impurities.

[0027] The above alloying element types and contents are selected in the embodiments of the present disclosure because:

[0028] C: It is the main element that determines the strength and hardness of wear-resistant steel. With the increase of carbon, the supersaturated martensite and lower bainite are deformed more violently, the strength and hardness are higher, but the brittleness increases at the same time. Considering that the consumption of C by TiC will reduce the hardness of the matrix, the range is controlled at 0.24~0.40%.

[0029] Si: It is a solid solution strengthening and strong deoxidizing element. It also inhibits carbide formation and stabilizes austenite. In this patent, Si can inhibit TiC coarsening during rolling and slow cooling, control TiC dispersion and refinement, retain more of the supercooled austenite to lower bainite phase transformation range, and improve the wear resistance of the final structure. The range is controlled within 1.10-1.70%.

[0030] Mn: It is a solid solution strengthening element and an austenite stabilizing element, which is beneficial to retaining more austenite to room temperature. However, too high a Mn content will aggravate the segregation of the steel billet and cause crack initiation. In order to reduce the risk of cracks, the range is controlled between 1.2 and 1.8%.

[0031] P and S: are inevitable impurities in steel, and the range of P is controlled to be ≤ 0.015% and S ≤ 0.003%.

[0032] Cr: It is a solid solution strengthening element that can increase the self-corrosion potential of the matrix. When the Cr content is high, the alkaline corrosion resistance of the steel matrix is ​​significantly enhanced. Cr and C can form fine precipitation phases to enhance the wear resistance of the steel. The composite addition of Cr and Mo can effectively enhance the hardenability of the steel plate and increase the hardened layer of the steel. It is an alloying element that effectively improves the corrosion and wear resistance of the steel. Cr is also an austenite stabilizing element. However, a large amount of Cr added will cause the segregation of the steel billet to increase, and is not conducive to cost control and the weldability of the steel. The range is controlled at 0.30-0.70%.

[0033] Cu: It is an element that improves the alkaline corrosion resistance of steel. It can increase the self-corrosion potential of the matrix and improve the alkaline corrosion resistance of steel. However, excessive addition of Cu will increase the crack risk of the steel plate. The range is controlled at 0.10~0.40%.

[0034] Ni: It is an element that improves the alkaline corrosion resistance of steel. It can increase the self-corrosion potential of the matrix and improve the alkaline corrosion resistance of steel. At the same time, Ni can improve the toughness of steel and inhibit the surface cracks of steel plates caused by Cu addition. At the same time, Ni is a grain boundary segregation element, which enhances the grain boundary strength, improves the crack resistance of steel, and can reduce the phase transition temperature of steel. However, due to the high price of Ni, the range is controlled at 0.1~0.4%.

[0035] Mo: It can delay the ferrite phase transformation and is an effective element for improving the hardenability of steel. It can increase the depth of the hardened layer of steel and improve the wear resistance of steel. Mo is also a strong carbide-forming element. Its addition in combination with Ti can promote the precipitation of Ti-Mo composite carbides and refine the precipitated phase. The range is controlled between 0.1 and 0.55.

[0036] Sb: Producing a dense rust layer is an important means of improving the corrosion resistance of steel plates. Rapidly forming a dense rust layer on the steel plate surface can isolate corrosive ions. However, the rust layer is significantly lower in hardness than the substrate and is prone to shedding. Considering the effects of wear and corrosion, this can actually be detrimental to the abrasive properties of the steel plate. Therefore, for weak corrosive wear conditions, the rust layer is not the primary concern, but rather the combined performance of the substrate's self-corrosion potential and hardness.

[0037] Sb can make the corrosion products dense and inhibit the corrosion of H2O, O2, Cl- and SO4 2- Sb diffuses into the steel matrix in an isotropic manner, concentrating near the steel matrix in an alkaline environment. Combining this with the concentrated Cu, it forms Cu2Sb, a poorly alkali-soluble element that resists further corrosion of the steel matrix. However, Sb is a low-melting-point element and tends to concentrate at grain boundaries, causing intergranular cracking. The risk of steel plate cracking increases rapidly with increasing Sb content, but is controlled within a range of 0.06-0.10%.

[0038] Ti: A strong carbide-forming element. TiC precipitates can form hydrogen traps, effectively fixing free hydrogen in the steel and preventing hydrogen from accumulating at crack sources and causing delayed cracking. This is the key technology for the wear-resistant steel of this invention to resist cracking. The TiC content is controlled within a range of 0.10% to 0.18%.

[0039] Als: It is a strong deoxidizing element, and its content is controlled within the range of 0.015% to 0.045%.

[0040] B: It can delay the ferrite phase transformation and is an effective element for improving the hardenability of steel. However, it tends to concentrate at the grain boundaries. When the B content is too high, it will precipitate at the grain boundaries, reducing the grain boundary strength and worsening the toughness of the steel. The range is controlled within 0.0008-0.0016%.

[0041] The chemical composition of the wear-resistant steel of Examples 1-15 of the present disclosure is shown in Table 1:

[0042] Table 1 Chemical composition of example steel (wt%)

[0043] C Si Mn P S Cr Cu Ni Mo Sb Ti Als B Example 1 0.24 1.25 1.46 0.0150 0.0022 1.25 0.19 0.19 0.31 0.06 0.13 0.050 0.0012 Example 2 0.26 1.47 1.55 0.0095 0.0028 1.56 0.23 0.37 0.23 0.06 0.18 0.042 0.0011 Example 3 0.25 1.17 1.20 0.0133 0.0016 1.64 0.1 0.1 0.10 0.09 0.12 0.026 0.001 Example 4 0.26 1.50 1.60 0.0087 0.0024 1.38 0.17 0.25 0.15 0.09 0.16 0.036 0.0011 Example 5 0.29 1.25 1.68 0.0094 0.0017 1.58 0.1 0.29 0.24 0.09 0.11 0.015 0.0008 Example 6 0.30 1.36 1.34 0.0118 0.0017 1.38 0.14 0.25 0.23 0.07 0.15 0.043 0.0014 Example 7 0.31 1.10 1.66 0.0113 0.0028 1.34 0.22 0.35 0.54 0.10 0.18 0.041 0.001 Example 8 0.32 1.18 1.68 0.0104 0.0021 1.1 0.35 0.26 0.36 0.10 0.1 0.025 0.0012 Example 9 0.33 1.52 1.32 0.0094 0.0017 1.30 0.29 0.2 0.34 0.06 0.16 0.02 0.0015 Example 10 0.24 1.42 1.80 0.0118 0.0027 1.29 0.19 0.40 0.3 0.09 0.18 0.031 0.0014 Example 11 0.36 1.33 1.7 0.0127 0.003 1.55 0.40 0.23 0.51 0.09 0.14 0.045 0.0013 Example 12 0.39 1.39 1.30 0.0084 0.002 1.70 0.17 0.16 0.55 0.06 0.17 0.045 0.0011 Example 13 0.38 1.29 1.71 0.0144 0.003 1.43 0.18 0.35 0.18 0.09 0.18 0.045 0.0016 Example 14 0.29 1.70 1.24 0.0109 0.0021 1.42 0.13 0.31 0.42 0.07 0.1 0.038 0.0011 Example 15 0.40 1.62 1.72 0.0135 0.002 1.53 0.12 0.22 0.27 0.08 0.16 0.031 0.0015

[0044] In Examples 1-15 of the present disclosure, wear-resistant steel was prepared according to the chemical composition and content designed in Table 1. The specific process route was: molten iron pretreatment, converter steelmaking, LF furnace refining, RH vacuum degassing, continuous casting, slow cooling of the continuous casting, heating, rolling, slow cooling of the steel plate, and heat treatment, wherein:

[0045] For the slow cooling and heating process of continuous casting billets, the continuous casting billets enter a slow cooling pit with heating function or a heating furnace for heating and slow cooling. The temperature of the continuous casting billets at the beginning of slow cooling is ≥430℃. The continuous casting billets are heated to 500-580℃ and kept warm for 24-36h. Then the heating is stopped and the continuous casting billets are slowly cooled in the slow cooling pit or heating furnace for 24h-36h.

[0046] After slow cooling, the continuous casting slab is sent to the heating furnace with an entry temperature of ≥300°C, a heating temperature of 1100-1200°C, and a furnace time of 0.45-0.7 min / mm. The slow cooling and heating process parameters of the continuous casting slabs of Examples 1-15 of the present disclosure are shown in Table 2 below:

[0047] Table 2 Slow cooling and heating process of continuous casting slab in Example

[0048]

[0049]

[0050] In the rolling and slow cooling process, hot rolling is adopted, the starting rolling temperature is 950-1050°C, and the finishing rolling temperature is 900-1050°C.

[0051] After rolling, the steel plate is quickly stacked and slowly cooled off the line, with the stacking and slow cooling steel plate temperature of 540°C ≤ 640°C, and then slowly cooled to ≤ 150°C. The rolling and slow cooling process parameters of Examples 1-15 of the present disclosure are shown in Table 3 below:

[0052] Table 3 Rolling and slow cooling process of example steel

[0053]

[0054] The heat treatment process is set up as quenching and tempering, in which the steel plate quenching heating is divided into a high-temperature section and a cooling section. The high-temperature section temperature of the quenching heat treatment furnace is 840-880°C, and the high-temperature section time in the furnace is 1.4-2.0 min / min; the cooling section temperature is 740-780°C, and the cooling section time in the furnace is 0.8-1.4 min / min. The quenching heating process parameters of Examples 1-15 of the present disclosure are shown in Table 4 below:

[0055] Table 4 Quenching and heating process of example steel

[0056]

[0057]

[0058] After leaving the quenching heat treatment furnace, the steel plates are quenched in a roller quenching machine. The average cooling rate during quenching is 9-52°C / s, and the final quenching temperature is 280-380°C.

[0059] After quenching, the steel plate is immediately put into the tempering furnace. The steel plate temperature is ≥180°C, the tempering heating temperature is 180-240°C, and the tempering holding time is 4.0-6.0 min / mm. The quenching cooling and tempering process parameters of Examples 1-15 of the present disclosure are shown in Table 5:

[0060] Table 5 Quenching, cooling and tempering process of example steel

[0061]

[0062] In the above steps of the preparation method disclosed herein, the reasons for selecting the corresponding parameters are as follows:

[0063] The delayed cracking of wear-resistant steel is closely related to the H content and its state. The basic requirement for avoiding delayed cracking during use is that the H content in the steel is low and the heating and slow cooling of the billet can fully release hydrogen. The furnace entry temperature is ≥430℃ to avoid the billet temperature being too low, and H will accumulate in the billet at segregation, inclusions, etc., causing cracks. The billet is heated to 500-580℃ because the solid solubility of H in the ferrite phase is low and the H diffusion rate is fast at high temperatures. At the same time, considering that Sb has a low melting point and is prone to enrichment at grain boundaries to cause cracks, the heating temperature should not be too high. When hydrogen is reduced to a certain level, the diffusion efficiency decreases, and the risk of hydrogen-induced cracking in the billet has been eliminated. In order to balance production efficiency and billet quality, the holding time is controlled to 24-36 hours, and then heating is stopped and the billet is slowly cooled in the slow cooling pit or heating furnace for 24-36 hours.

[0064] Sb is a low-melting-point element and easily accumulates at the grain boundaries, causing cracks in the steel billet and rolled steel plate. Therefore, low-temperature steelmaking is required, with a heating temperature of 1100-1200°C. At the same time, a hot delivery process is adopted, with the billet entering the furnace temperature ≥300°C, shortening the heating time. The billet stays in the furnace for 0.45-0.7 min / mm.

[0065] Hot rolling is adopted to avoid TiC precipitation during the rolling process and to create temperature conditions for subsequent stacking and slow cooling. The starting rolling temperature is 950-1150°C and the finishing rolling temperature is 900-1050°C.

[0066] After rolling, the steel plate is in a high temperature state and the thickness specification is reduced. Rapid off-line stacking and slow cooling are conducive to the re-diffusion of hydrogen, reducing the H content in the steel plate and inhibiting the occurrence of hydrogen-induced cracks in the steel plate. In this patent, a large amount of Si element is added, and high-temperature and long-term stacking is required to promote the formation of a large amount of TiC precipitation phase inside the steel plate. This TiC precipitation phase is finer and will not dissolve back during the quenching and heating process. It will be retained until the final use structure. Therefore, the slow cooling process is extremely critical. The stacking temperature should be ≥540℃ to create the kinetic conditions for TiC precipitation. At the same time, considering that too high a temperature will cause Sb enrichment and lead to cracking risks, the stacking temperature should be ≤640℃.

[0067] Heat treatment includes quenching and tempering. The quenching heating of steel plates includes high temperature section and cooling section. The high temperature section of the quenching heat treatment furnace is 840-880℃, and the high temperature section is in the furnace for 1.4-2.0min / mm. Its purpose is to quickly heat the steel plate to the austenitizing temperature, providing organizational guarantee for the subsequent quenching of the steel plate to obtain martensite and lower bainite. However, excessively high temperature will lead to Sb enrichment at the grain boundary, increase the risk of cracks, and enlarge the austenite grains, reducing the low-temperature toughness of the steel plate. At the same time, excessively high temperature and the furnace time will promote the dissolution of TiC, reducing the number of hydrogen traps inside the steel plate, so the holding time is also It should not exceed 2.0min / mm; the temperature of the cooling section is 740~780℃, and the cooling section time in the furnace is 0.8~1.4min / mm. The purpose is to reduce the austenite to above the Ar3 temperature in the cooling section, that is, to ensure that the steel plate is in a fully austenitized state and the quenched steel plate is fully hardened. At the same time, the lower the starting quenching temperature of the steel plate, the lower the stress level of the steel plate during the quenching process, avoiding cracking of the wear-resistant steel due to the quenching process. At the same time, the design of the steel plate holding time takes into account the influence of the steel plate's uniform heat and Sb-induced cracks.

[0068] After leaving the quenching heat treatment furnace, the steel plate enters the roller quenching machine for quenching. In order to obtain sufficient martensitic transformation and avoid excessive stress in the steel plate caused by excessive cooling rate, which may lead to quenching cracks, the average quenching cooling rate is designed to be 9-52℃ / s; the quenching end temperature is limited to 280-380℃, in order to ensure that the supercooled austenite is quickly cooled to the lower bainite phase transformation range, while reducing the stress of the steel plate during quenching to avoid quenching cracks.

[0069] After quenching, the steel plate enters the tempering furnace immediately. The temperature of the steel plate entering the furnace is ≥180℃. This is to reduce the proportion of supercooled austenite transforming into martensite and transform austenite into lower bainite to enhance the wear resistance of the steel. At the same time, it is to form retained austenite. The tempering heating temperature is 180-240℃ and the tempering holding time is 4.0-6.0min / mm. The purpose is to allow C in the primary martensite to fully diffuse into the austenite, fully undergo bainite transformation, and retain more retained austenite to room temperature, thereby enhancing the toughness of the steel plate and hindering crack propagation.

[0070] The wear-resistant steels prepared in Examples 1-15 of the present disclosure were subjected to mechanical property tests. The mechanical properties of the example steels and the comparative example steels are shown in Table 6 below:

[0071] Table 6 Mechanical properties of example steel

[0072]

[0073] Wear tests were conducted on the test steels of Examples 2, 4, 5, 6, 14, and 15. Common low-alloy wear-resistant steels NM400, NM450, and NM500 with a thickness of 20 mm were selected as comparative examples. The wear test equipment was a wet rubber wheel abrasive wear tester. The wear specimen dimensions and test methods were in accordance with ASTM G105. The SiC sand particle size was 80-120 mesh. The solvent was a simulated alkaline coal mine water solution, the chemical composition of which is shown in Table 7. The test force was 120 kN, the rotation speed was 200 r / min, and the wear time was 10 min. The mechanical properties of the comparative steels are shown in Table 8, and the wear test results are shown in Table 9.

[0074] Table 7 Main chemical composition of simulated acid mine water (mg / L)

[0075] <![CDATA[Cl - ]]> <![CDATA[SO4 2- ]]> <![CDATA[Na + ]]> <![CDATA[Ca 2+ ]]> <![CDATA[Mg 2+ ]]> pH 133.2 1717.2 162.5 317.7 125.8 5

[0076] Table 8 Mechanical properties of comparative steel

[0077]

[0078] Table 9 Corrosion and wear test results

[0079]

[0080] According to Tables 6, 8, and 9, it can be seen that Examples 2 and 4 are all made of NM400 wear-resistant steel as compared to Comparative Example 1, and their mechanical properties are comparable, but Examples 2 and 4 are 1.24 and 1.26 times the wear resistance of Comparative Example 1; Examples 5 and 6 are all made of NM450 wear-resistant steel as compared to Comparative Example 2, and their mechanical properties are comparable, but Examples 5 and 6 are 1.19 and 1.22 times the wear resistance of Comparative Example 2; Examples 14 and 15 are all made of NM500 wear-resistant steel as compared to Comparative Example 3, and their mechanical properties are comparable, but Examples 14 and 15 are 1.12 and 1.14 times the wear resistance of Comparative Example 3. In summary, the wear-resistant steel prepared by the method of the present invention has better wear resistance under alkaline coal mine water conditions.

[0081] The above-described embodiments are merely examples of implementation methods of the present disclosure, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications, equivalent substitutions, and improvements without departing from the scope of the present disclosure, and these modifications are all within the scope of protection of the present disclosure. Therefore, the scope of protection of the present invention shall be based on the appended claims.

Claims

1. A method for preparing alkaline coal water corrosion resistant wear-resistant steel, characterized in that: The alloying elements of the wear-resistant steel are set to be as follows according to weight percentage: C: 0.24%~0.40%, Si: 1.10%~1.70%, Mn: 1.20%~1.80%, P: ≤0.015%, S: ≤0.003%, Cr: 1.10%~1.70%, Cu: 0.10%~0.40%, Ni: 0.10%~0.40%, Mo: 0.10%~0.55%, Sb: 0.06%~0.10%, Ti: 0.10%~0.18%, Als: 0.015%~0.05%, B: 0.0008%~0.0016%, the balance is Fe and unavoidable impurities; The method for preparing wear-resistant steel includes the steps of continuous casting, slow cooling and heating, rolling and heat treatment of the continuous casting billet. In the slow cooling and heating steps, the continuous casting billet is placed in a slow cooling pit or a heating furnace with a heating function for heating and slow cooling. When slow cooling begins, the temperature of the continuous casting billet is ≥430°C. The continuous casting billet is kept at 500°C to 580°C for 24 to 36 hours. After heating is stopped, the continuous casting billet is cooled in the slow cooling pit or the heating furnace for 24 to 36 hours. The heat treatment process is set to quenching treatment and tempering treatment. The process of quenching and heating the steel plate in the quenching heat treatment furnace is divided into a high temperature section and a cooling section. The temperature of the high temperature section of the quenching heat treatment furnace is 840°C to 880°C, and the time in the high temperature section is 1.4 min / mm to 2.0 min / mm; the temperature of the cooling section is 740°C to 780°C, and the time in the cooling section is 0.8 min / mm to 1.4 min / mm. After the steel plate leaves the quenching heat treatment furnace, it enters a roller quenching machine for quenching. The average cooling rate during quenching is 9°C to 52°C / s, and the final quenching temperature is 280°C to 380°C. After the quenching treatment, the steel plate is immediately put into a tempering furnace. The furnace entry temperature of the steel plate is ≥180° C., the tempering heating temperature is 180° C. to 240° C., and the tempering holding time is 4.0 min / mm to 6.0 min / mm.

2. The method for preparing wear-resistant steel according to claim 1, characterized in that: After slow cooling, the continuous casting billet is sent to a heating furnace with an entry temperature of ≥300° C., a heating temperature of 1100° C. to 1200° C., and a furnace time of 0.45 min / mm to 0.7 min / mm.

3. The method for preparing wear-resistant steel according to claim 2, characterized in that: In the rolling, a hot rolling method is adopted, the starting rolling temperature is 950°C to 1050°C, and the finishing rolling temperature is 900°C to 1050°C.

4. The method for preparing wear-resistant steel according to claim 3, characterized in that: In the slow cooling process, after the rolling, the steel plates are stacked and slowly cooled offline, the temperature of the stacked and slowly cooled steel plates is 540°C≤640°C, and the temperature is cooled to ≤150°C.

5. An alkaline coal water corrosion-resistant wear-resistant steel, characterized by: The method is prepared by any one of claims 1 to 4.

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