A wear-resistant steel plate resistant to coal mine acidic mine water corrosion and a preparation method thereof

Abstract

The application discloses an anti-corrosion wear-resistant steel plate for coal mine acid mine water and a preparation method thereof. The wear-resistant steel plate is prepared by adding Cr-Cu-Ni-Sb in combination, so that the anti-corrosion ability of the wear-resistant steel plate for coal mine acid mine water is effectively enhanced, and the relative wear resistance of the wear-resistant steel plate is 1.16-1.36 times that of a low-alloy wear-resistant steel plate with the same hardness level. The preparation method is characterized by process design for inhibiting crack generation of the Sb-containing wear-resistant steel plate in the production process, Nb and Mo addition in combination, heat treatment heating path design, reservation of a large amount of Nb and Mo composite carbides in the quenched steel plate, and use of the Nb and Mo composite carbides as hydrogen traps for greatly improving the anti-hydrogen-induced crack ability of the Sb-containing wear-resistant steel plate in the service process, so that the acid mine water corrosion and wear-resistant wear-resistant steel plate with excellent mechanical properties and anti-hydrogen-induced crack is finally obtained.

Description

Technical Field

[0001] This invention relates to the field of metallic materials, and more particularly to wear-resistant steel resistant to acidic coal mine water corrosion and its preparation method. Background Technology

[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 service life depends not only on the wear intensity of the operating conditions but also on the corrosive environment. Scraper conveyors are key equipment in coal mines, enduring high-intensity wear from coal and gangue during their long-term underground service. Low-alloy wear-resistant steel is primarily used for the plates and floor plates. Simultaneously, the severe corrosion of wear-resistant steel by mine water transforms its service conditions from simple wear to corrosive wear, exacerbating the wear. Therefore, it is necessary to develop corrosion-resistant wear-resistant steel plates specifically for the mining environment to reduce wear loss and extend the service life of wear-resistant steel and related equipment.

[0003] Publication number CN114774772A discloses a corrosion-resistant 500HB martensitic wear-resistant steel plate. Although the corrosion resistance of this 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] The patent application CN110387507B discloses an HB500 grade wear-resistant steel for transporting corrosive slurries. However, the patent document does not demonstrate the corrosion resistance or abrasion resistance through testing. Furthermore, its manufacturing process includes online quenching, cooling from a temperature of not less than 825°C to room temperature at a cooling rate of 55–65°C / s. This process is not conducive to the control of internal cracks in high-grade wear-resistant steel plates.

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

[0006] CN112159934A discloses a corrosion-resistant and wear-resistant steel plate that adds a large amount of Cr to ensure corrosion resistance in acidic environments. However, this significantly increases the alloy cost of the steel and also noticeably deteriorates its weldability, which is not conducive to its widespread application.

[0007] Publication number CN113106341B discloses a high-strength, tough, weldable, corrosion-resistant, and wear-resistant steel plate with controlled Mo / Ti ratio of 1.8% to 7.0% and Ti / Al ratio of 3% to 13%. However, this patent does not demonstrate its corrosion or wear resistance through testing, 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.

[0008] In summary, current corrosion-resistant and wear-resistant steels primarily achieve their corrosion resistance by adding large amounts of alloying elements such as Cr, Ni, and Mo. However, this increases the cost of the steel plates and hinders welding. While adding Sb and Sn can avoid cost and weldability issues, their low melting point makes them highly susceptible to cracking in wear-resistant steels, especially those used in coal mine scraper conveyors, where cracking can cause significant losses. Summary of the Invention

[0009] In view of this, the present disclosure provides a method for preparing wear-resistant steel resistant to acidic mine water corrosion in coal mines. This method not only improves the wear-resistant steel's corrosion and wear resistance under acidic mine water conditions in coal mines, but also ensures that the steel plate does not crack during the manufacturing process and has strong resistance to delayed cracking during service.

[0010] In addition, this disclosure also provides wear-resistant steel prepared by the above-described preparation method.

[0011] In the first aspect, the method for preparing the wear-resistant steel resistant to corrosion by acidic mine water in coal mines, wherein the chemical composition of the wear-resistant steel, by weight percentage, is as follows:

[0012] C: 0.13%–0.30%, Si: 0.15%–0.50%, Mn: 0.60%–1.20%, P: ≤0.015%, S: ≤0.003%, Cr: 0.40%–0.80%, Cu: 0.20%–0.50%, Ni: 0.10%–0.40%, Mo: 0.10%–0.55%, Sb: 0.06%–0.10%, Nb: 0.02%–0.08%, Ti: 0.006%–0.018%, Als: 0.015%–0.05%, B: 0.0008%–0.0016%, with the balance being Fe and unavoidable impurities.

[0013] In this disclosure and possible embodiments, the method includes the steps of slow cooling, heating, rolling, and heat treatment of continuously cast steel billets, wherein:

[0014] In the process of slow cooling and heating of the continuously cast steel billet, the continuously cast steel billet is slow cooled using a slow cooling pit or heating furnace with heating function. The temperature of the continuously cast steel billet is ≥450℃ at the beginning of slow cooling. After the continuously cast steel billet is heated to 520℃~580℃ and held for 24h~36h, the heating is stopped and the continuously cast steel billet is allowed to cool naturally in the slow cooling pit or heating furnace for 24h~36h.

[0015] After the natural cooling process is completed, the continuously cast steel billet is sent to a heating furnace with an entry temperature ≥300℃ and a heating temperature of 1100℃~1200℃. The continuous cast steel billet is in the furnace for 0.45min / mm~0.7min / mm.

[0016] In this disclosure and possible embodiments, the rolling process adopts a two-stage rolling method, with the first rolling temperature being 950℃~1050℃ and the first finishing rolling temperature being 950℃~1050℃, and the intermediate billet thickness / steel plate thickness being ≥2; the second rolling temperature being 820℃~920℃ and the second finishing rolling temperature being 820℃~880℃.

[0017] In this disclosure and possible embodiments, the rolled steel plates are stacked and slowly cooled, with the temperature of the stacked and slowly cooled steel plates ranging from 300°C to 580°C, and then slowly cooled to 150°C.

[0018] In this disclosure and possible embodiments, the heat treatment process is divided into quenching treatment and tempering treatment. The process of quenching and heating the steel plate in the quenching heat treatment furnace is divided into a low temperature section, a high temperature section and a cooling section.

[0019] The temperature of the low-temperature section is 540℃~580℃, and the furnace time in the low-temperature section is 1.8min / mm~3.0min / mm; the temperature of the high-temperature section is 860℃~900℃, and the furnace time in the high-temperature section is 0.8min / mm~1.4min / mm; the temperature of the cooling section is 740℃~780℃, and the furnace time in the cooling section is 0.min / mm~1.0min / mm.

[0020] In this disclosure and possible embodiments, the steel plate is directly fed into a roller press quenching machine after exiting the quenching heat treatment furnace for further quenching. The average cooling rate during quenching is 9°C / s to 52°C / s, and the final quenching temperature is 120°C to 280°C.

[0021] In this disclosure and possible embodiments,

[0022] In the tempering process, the heating temperature is 200℃~260℃, and the tempering holding time is 4.0min / mm~6.0min / mm.

[0023] Secondly, the wear-resistant steel resistant to corrosion by acidic mine water in coal mines is prepared by the method described in the first aspect.

[0024] The present invention has the following beneficial effects:

[0025] (1) The wear-resistant steel of the present invention effectively enhances the corrosion resistance of wear-resistant steel against acidic mine water in coal mines through the composite addition of Cr-Cu-Ni-Sb, and its relative wear resistance is 1.16 to 1.36 times that of low alloy wear-resistant steel of the same hardness level.

[0026] (2) Through process design, this invention effectively suppresses the problem of cracking in Sb-containing wear-resistant steel during production. By adding Nb and Mo composites and designing the heat treatment heating path, a large amount of Nb and Mo composite carbides are retained in the quenched steel plate, which serve as hydrogen traps. This significantly improves the resistance of Sb-containing wear-resistant steel to hydrogen-induced cracking during service, resulting in wear-resistant steel with excellent mechanical properties and resistance to hydrogen-induced cracking in acidic coal mine water corrosion. Detailed Implementation

[0027] The present disclosure is described below based on embodiments; however, it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail. Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as encompassing rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0028] This disclosure provides a detailed description of the wear-resistant steel resistant to acidic mine water corrosion in coal mines and its preparation method through Examples 1-15. The alloying elements constituting the wear-resistant steel resistant to acidic mine water corrosion in coal mines, by weight percentage, are as follows:

[0029] C: 0.13–0.30%, Si: 0.15–0.50%, Mn: 0.60–1.20%, P: ≤0.015%, S: ≤0.003%, Cr: 0.40–0.80%, Cu: 0.20–0.50%, Ni: 0.10–0.40%, Mo: 0.10–0.55%, Sb: 0.06–0.10%, Nb: 0.02–0.08%, Ti: 0.006–0.018%, Als: 0.015–0.05%, B: 0.0008–0.0016%, balance being Fe and unavoidable impurities.

[0030] The above-mentioned alloying elements and their contents were selected in this embodiment because:

[0031] C is the main element that determines the strength and hardness of wear-resistant steel. As carbon increases, the distortion of supersaturated martensite becomes more intense, resulting in higher strength and hardness, but at the same time, brittleness increases. The range is controlled between 0.13% and 0.30%.

[0032] Si is a solid solution strengthening element and a strong deoxidizing element that can improve the strength and hardness of steel. However, excessive addition will reduce the plasticity and toughness of the steel plate and aggravate the surface decarburization of the steel. The range should be controlled between 0.15% and 0.5%.

[0033] Mn is a solid solution strengthening element that can improve the strength of steel. However, excessive Mn content can aggravate segregation in steel billets, leading to crack initiation. Therefore, to reduce the risk of cracking, the Mn content should be controlled within the range of 0.6% to 1.2%.

[0034] P and S are unavoidable impurities in steel, and the range should be controlled as P ≤ 0.015% and S ≤ 0.003%.

[0035] Cr: A solid solution strengthening element and an element that improves the corrosion resistance of steel. When the Cr content is high, the acid corrosion resistance of the steel is significantly enhanced. Cr and C can also form fine precipitates, enhancing the wear resistance of the steel. The combined addition of Cr and Mo can effectively enhance the hardenability of the steel plate and increase the hardened layer. It is an effective alloying element for improving the corrosion and wear resistance of steel. However, excessive Cr addition can exacerbate segregation in the billet and is detrimental to cost control and weldability. The recommended range is 0.60–1.00%.

[0036] Cu (Cu) is an element that improves the acid corrosion resistance of steel. It can make corrosion products more compact and inhibit the diffusion of H2O, O2, Cl-, and SO42- into the steel matrix. However, excessive Cu addition will increase the risk of cracking in the steel plate. The range should be controlled between 0.20% and 0.60%.

[0037] Ni is an element that improves the acid corrosion resistance of steel. It can make corrosion products more compact and inhibit the diffusion of H2O, O2, Cl- and SO42- into the steel matrix. At the same time, Ni can improve the toughness of steel and inhibit surface cracks in steel plates caused by Cu addition. Ni is also a grain boundary segregating element, which enhances grain boundary strength, improves the crack resistance of steel, and can lower the phase transformation temperature of steel. However, due to the high price of Ni, the range is controlled at 0.1% to 0.4%.

[0038] Mo (Mo) 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 and improve the wear resistance of steel. At the same time, Mo is a strong carbide-forming element; its addition in combination with Nb can promote the precipitation of Nb-Mo complex carbides, thus enhancing the precipitation effect. Furthermore, Mo…

[0039] Sb (Scalcite): It can densify corrosion products and inhibit the diffusion of H2O, O2, Cl-, and SO42- into the steel matrix. It can accumulate near the steel matrix in acidic environments, forming Cu2Sb, which is insoluble in acids, with the accumulated Cu, thus resisting further corrosion of the steel matrix. However, Sb is a low-melting-point element and easily accumulates at grain boundaries, causing grain boundary cracks. With increasing Sb content, the risk of cracking in the steel plate increases rapidly, and the range of cracking should be controlled within...

[0040] Nb is a strong carbide-forming element that can precipitate and refine grains during controlled rolling, improving the strength and toughness of steel. Simultaneously, Nb carbides and Nb-Mo composite carbides can form hydrogen traps, effectively fixing free hydrogen in the steel and preventing hydrogen from accumulating at crack initiation sites, thus preventing delayed cracking. This is a key technology for crack resistance in the wear-resistant steel of this invention.

[0041] Ti: It can form TiN with N. TiN has high temperature stability. On the one hand, it inhibits the growth of austenite during the steel heating process, and on the other hand, it reduces the solid solution of N. Both of these effects can increase the toughness of steel. When the Ti content is too high, it will significantly increase the number of large particle inclusions in the steel. The range should be controlled between 0.45% and 0.55%.

[0042] Als: a strong deoxidizing element, with a concentration range of 0.015% to 0.045%.

[0043] B: It can delay the ferrite phase transformation and is an effective element to improve the hardenability of steel. However, it tends to agglomerate at the grain boundaries. When the B content is too high, it will precipitate at the grain boundaries, reduce the grain boundary strength, and deteriorate the toughness of the steel. The range should be controlled between 0.0008 and 0.0016%.

[0044] The chemical composition of the wear-resistant steels in Examples 1-15 is shown in Table 1:

[0045] Table 1. Chemical composition (wt%) of the steel in the examples

[0046] Example 1 0.13 0.34 1.12 0.015 0.0024 0.52 0.23 0.13 0.16 0.042 0.082 0.008 0.026 0.0012 Example 2 0.14 0.24 1.20 0.012 0.0014 0.59 0.46 0.26 0.10 0.020 0.076 0.006 0.017 0.0016 Example 3 0.16 0.17 1.17 0.014 0.0017 0.67 0.27 0.15 0.55 0.080 0.10 0.010 0.05 0.0016 Example 4 0.17 0.45 1.05 0.009 0.0020 0.72 0.35 0.20 0.54 0.074 0.097 0.015 0.034 0.0011 Example 5 0.19 0.15 1.10 0.011 0.0030 0.77 0.33 0.18 0.34 0.051 0.091 0.018 0.034 0.0010 Example 6 0.2 0.42 1.07 0.012 0.0024 0.40 0.24 0.10 0.17 0.046 0.086 0.009 0.017 0.0015 Example 7 0.21 0.33 1.02 0.012 0.0021 0.46 0.20 0.14 0.16 0.038 0.076 0.012 0.027 0.0014 Example 8 0.22 0.19 1.00 0.011 0.0030 0.53 0.29 0.16 0.15 0.041 0.064 0.014 0.021 0.000. Example 9 0.23 0.37 0.96 0.008 0.0018 0.62 0.33 0.40 0.12 0.033 0.06 0.015 0.019 0.0009 Example 10 0.23 0.31 0.87 0.009 0.0016 0.44 0.36 0.20 0.35 0.065 0.068 0.016 0.026 0.0010 Example 11 0.24 0.41 1.0 0.011 0.0021 0.80 0.41 0.31 0.26 0.054 0.070 0.011 0.022 0.0012 Example 12 0.25 0.50 0.75 0.010 0.0026 0.78 0.44 0.22 0.22 0.059 0.076 0.011 0.024 0.0013 Example 13 0.27 0.44 0.6 0.009 0.0022 0.62 0.49 0.22 0.41 0.070 0.077 0.013 0.031 0.0008 Example 14 0.29 0.26 0.92 0.010 0.0023 0.66 0.50 0.35 0.44 0.072 0.081 0.010 0.04 0.0011 Example 15 0.30 0.22 1.06 0.010 0.0020 0.61 0.34 0.27 0.50 0.071 0.066 0.018 0.015 0.0010

[0047] Examples 1-15 of this disclosure prepare wear-resistant steel according to the chemical composition and content designed in Table 1. The specific process route is as follows: hot metal pretreatment, converter steelmaking, LF furnace refining, RH vacuum degassing, continuous casting billet, slow cooling of billet, heating, rolling, slow cooling of steel plate, and heat treatment, wherein:

[0048] For the slow cooling and heating process of steel billets, the continuously cast steel billets are placed in a slow cooling pit or heating furnace with heating function for slow cooling. The initial slow cooling temperature of the billet is ≥450℃, and the billet is heated to 520~580℃ and held for 24~36 hours. Heating is then stopped, and the billet is slowly cooled in the slow cooling pit or heating furnace for 24~36 hours. After slow cooling, the billet is hot-transferred to the heating furnace with an entry temperature ≥300℃ and a heating temperature of 1100~1200℃. The billet time in the furnace is 0.45~0.7 min / mm. The process parameters for the slow cooling and heating of steel billets in Examples 1-15 of this disclosure are shown in Table 2 below:

[0049] Table 2. Slow cooling and heating process of steel billets in the examples.

[0050]

[0051]

[0052] In the rolling and slow cooling processes, a two-stage rolling method is adopted. The first rolling temperature is 950-1050℃, the first finishing rolling temperature is 950-1050℃, the intermediate billet thickness / steel plate thickness is ≥2, the second rolling temperature is 820-920℃, and the second finishing rolling temperature is 820-880℃. After rolling, the steel plate is quickly removed from the line and stacked for slow cooling. The stacked slow-cooling temperature is ≤580℃ (300℃≤580℃), and then slowly cooled to ≤150℃. The rolling and slow cooling process parameters of Examples 1-15 of this disclosure are shown in Table 3 below:

[0053] Table 3. Rolling and slow cooling processes of the steel in the examples.

[0054]

[0055] The heat treatment process in this disclosure includes quenching and tempering. The quenching heating of the steel plate includes a low-temperature section, a high-temperature section, and a cooling section. The temperature of the low-temperature section of the quenching heat treatment furnace is 540–580℃, and the furnace time in the low-temperature section is 1.8–3.0 min / mm; the temperature of the high-temperature section is 860–900℃, and the furnace time in the high-temperature section is 0.8–1.4 min / mm; the temperature of the cooling section is 740–780℃, and the furnace time in the cooling section is 0.6–1.0 min / mm. The quenching heating process parameters of embodiments 1-15 of this disclosure are shown in Table 4 below:

[0056] Table 4. Quenching and heating process of steel in the examples.

[0057]

[0058] After exiting the quenching heat treatment furnace, the steel plates are quenched in a roller press quenching machine. The average cooling rate during quenching is 9–52 °C / s, and the final quenching temperature is 120–280 °C. The tempering heating temperature is 200–260 °C, and the tempering holding time is 4.0–6.0 min / mm. The quenching, cooling, and tempering process parameters for Examples 1-15 of this disclosure are shown in Table 5.

[0059] Table 5. Quenching, Cooling, and Tempering Processes of the Steel in the Examples

[0060]

[0061]

[0062] The reasons for selecting the appropriate parameters in the above steps of the preparation method disclosed herein are as follows:

[0063] Delayed cracking in wear-resistant steel is closely related to hydrogen content and its state. A basic requirement for avoiding delayed cracking during use is a low hydrogen content in the steel, and slow heating and cooling of the billet allows for sufficient hydrogen release. The purpose of using a furnace entry temperature ≥450℃ in this disclosure is to prevent excessively low billet temperatures, which could lead to hydrogen accumulation and cracking at segregation points and inclusions within the billet. Heating the billet to 520–580℃ is because hydrogen has low solid solubility in the ferrite phase, and its diffusion rate is faster at higher temperatures. Considering that Sb has a low melting point and is prone to enrichment at grain boundaries, resulting in cracking, the heating temperature should not be too high. Once hydrogen levels decrease to a certain point, diffusion efficiency declines, and the risk of hydrogen-induced cracking in the billet is eliminated. To balance production efficiency and billet quality, the holding time is controlled at 24–36 hours, after which heating is stopped, and the billet is allowed to cool slowly in a slow cooling pit or furnace for 24–36 hours.

[0064] Because Sb is a low-melting-point element, it is easy to accumulate at grain boundaries, causing cracks in steel billets and rolled steel plates. Therefore, the preparation method disclosed herein requires low-temperature steelmaking with a heating temperature of 1100–1200℃. At the same time, a hot delivery process is adopted, with the steel billet entering the furnace at a temperature ≥300℃, shortening the heating time, and the steel billet in the furnace for 0.45–0.7 min / mm.

[0065] The purpose of employing a two-stage rolling method is to refine the steel plate grains, ensuring the strength and toughness of the steel plate, while simultaneously promoting the precipitation of large amounts of Nb carbides. The embodiments of this disclosure are designed with a first rolling temperature of 950–1150°C, a first finishing rolling temperature of 980–1100°C, an intermediate billet thickness / steel plate thickness ≥ 2, a second rolling temperature of 820–920°C, and a second finishing rolling temperature of 820–880°C.

[0066] Because the steel plate is in a high-temperature state after rolling and the thickness is reduced, rapid removal from the production line and slow cooling by stacking facilitates the re-diffusion of hydrogen, reduces the H content in the steel plate, and inhibits the occurrence of hydrogen-induced cracks in the steel plate. In order to avoid the risk of cracks caused by Sb enrichment, the stacking temperature of the steel plate is 300℃≤580℃. In order to balance production efficiency, the steel plate is designed to be slowly cooled to ≤150℃ before entering the next production process.

[0067] The heat treatment in this embodiment includes quenching and tempering. The quenching heating of the steel plate is designed to be divided into a low-temperature section, a high-temperature section, and a cooling section. The low-temperature section of the quenching heat treatment furnace is designed to be 540–580°C, with a furnace time of 1.8–3.0 min / mm. This aims to continue promoting the outward diffusion of hydrogen (H) from the steel plate, reducing its H content, and to promote the precipitation and growth of large quantities of Nb and Mo composite carbides through prolonged holding. These carbides will provide a large number of hydrogen traps within the steel plate. Considering that excessively high temperatures can cause Sb enrichment at grain boundaries and lead to cracks, the low-temperature holding temperature should not exceed 580°C. The high-temperature section is designed to be 860–900°C, with a furnace time of 0.8–1.4 min / mm. This aims to rapidly heat the steel plate to its austenitizing temperature, providing structural support for subsequent quenching to obtain martensite. However, excessively high temperatures can lead to grain boundary… Sb enrichment increases the risk of cracking and enlarges austenite grains, reducing the low-temperature toughness of the steel plate. Excessive temperature also accelerates the dissolution of Nb and Mo composite carbides, significantly reducing the number of hydrogen traps inside the steel plate. Therefore, the holding time should not exceed 1.4 min / mm. The designed cooling section temperature is 740–780℃, and the furnace time during the cooling section is 0.6–1.0 min / mm. The purpose is to reduce the austenite temperature to above Ar3 during the cooling section, ensuring the steel plate is fully austenitized and fully hardened. Simultaneously, the lower the initial quenching temperature, the lower the stress level of the steel plate during quenching, preventing cracking of the wear-resistant steel during quenching. The design of the holding time also considers the homogenization of the steel plate and the impact of Sb-induced cracking.

[0068] After exiting the quenching heat treatment furnace, the steel plate enters a roller press quenching machine for further quenching. This is to achieve a full martensitic transformation while avoiding excessive cooling rate that could cause excessive stress in the steel plate and lead to quenching cracks. The designed average cooling rate for quenching is 9–52℃ / s; and the quenching end temperature is limited to 100–250℃. The purpose is to reduce the stress in the steel plate during the quenching process, avoid quenching cracks, and ensure that the austenite in the steel plate can fully complete the martensitic transformation.

[0069] Tempering is the main technical means to reduce residual stress after quenching. Under the premise of ensuring the hardness of the steel plate, the residual stress of the steel plate should be fully released. In the embodiments of this disclosure, the tempering heating temperature is designed to be 200-260℃ and the tempering holding time is 4.0-6.0 min / mm.

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

[0071] Table 6 Mechanical properties of the steel in the examples

[0072]

[0073]

[0074] This disclosure presents wear tests on the wear-resistant steels of Examples 3, 4, 5, 7, 12, and 14, using NM400, NM450, and NM500 ordinary low-alloy wear-resistant steels with a thickness of 20 mm as comparative examples. The wear test equipment was a wet rubber wheel abrasive wear tester. The wear sample size and test method followed ASTM G65. The SiC sand particle size was 80–120 mesh, the solvent was simulated acidic mine water (its chemical composition is shown in Table 7), the test force was 140 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.

[0075] Table 7. Main chemical composition (mg / L) of simulated acidic mine water in coal mines

[0076] 133.2 1717.2 162.5 317.7 125.8 5

[0077] Table 8 Mechanical properties of comparative steels

[0078]

[0079] Table 9 Results of Corrosion and Wear Tests

[0080]

[0081] According to Tables 6, 8, and 9, Examples 3 and 4 are all NM400 wear-resistant steel, and their mechanical properties are comparable. However, Examples 3 and 4 have 1.33 and 1.36 times the relative wear resistance of Comparative Example 1, respectively. Examples 5 and 7 are all NM450 wear-resistant steel, and their mechanical properties are comparable. However, Examples 5 and 7 have 1.22 and 1.24 times the relative wear resistance of Comparative Example 2, respectively. Examples 12 and 14 are all NM500 wear-resistant steel, and their mechanical properties are comparable. However, Examples 12 and 14 have 1.16 and 1.17 times the relative wear resistance of Comparative Example 3, respectively. In summary, the wear-resistant steel prepared using the method of this patent exhibits superior wear resistance under acidic coal mine water conditions.

[0082] The embodiments described above are merely illustrative of implementation methods of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent disclosure. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent disclosure should be determined by the appended claims.

Claims

1. A method for preparing wear-resistant steel resistant to corrosion by acidic mine water in coal mines, characterized in that, The chemical composition of the wear-resistant steel, by weight percentage, is as follows: C: 0.13%~0.30%, Si: 0.15%~0.50%, Mn: 0.60%~1.20%, P: ≤0.015%, S: ≤0.003%, Cr: 0.40%~0.80%, Cu: 0.20%~0.50%, Ni: 0.10%~0.40%, Mo: 0.10%~0.55%, Sb: 0.06%~0.10%, Nb: 0.02%~0.08%, Ti: 0.006%~0.018%, Als: 0.015%~0.05%, B: 0.0008%~0.0016%, balance Fe and unavoidable impurities; The method for preparing the wear-resistant steel includes the steps of slow cooling, heating, rolling and heat treatment of continuously cast steel billets. In the slow cooling and heating steps of the continuously cast steel billets, the continuously cast steel billets are slow cooled using a slow cooling pit or heating furnace with heating function. The initial temperature of the continuously cast steel billets is ≥450℃. After the continuously cast steel billets are heated to 520℃~580℃ and held at that temperature for 24 h~36 h, the heating is stopped and the continuously cast steel billets are allowed to cool naturally in the slow cooling pit or heating furnace for 24 h~36 h. After the natural cooling process is completed, the continuously cast steel billet is sent to a heating furnace with an entry temperature ≥300℃ and a heating temperature of 1100℃~1200℃. The continuous cast steel billet is in the furnace for 0.45 min / mm~0.7 min / mm.

2. The method for preparing wear-resistant steel according to claim 1, characterized in that: The rolling process adopts a two-stage rolling method. The first rolling temperature is 950℃~1050℃, the first finishing rolling temperature is 950℃~1050℃, and the intermediate billet thickness / steel plate thickness is ≥2. The second rolling temperature is 820℃~920℃, and the second finishing rolling temperature is 820℃~880℃.

3. The method for preparing wear-resistant steel according to claim 2, characterized in that: The rolled steel plates are stacked and slowly cooled. The temperature of the stacked and slowly cooled steel plates is 300℃≤580℃, and then slowly cooled to ≤150℃.

4. The method for preparing wear-resistant steel according to claim 3, characterized in that: The heat treatment process is divided into quenching and tempering. The process of quenching and heating the steel plate in the quenching heat treatment furnace is divided into a low temperature section, a high temperature section and a cooling section. The temperature of the low-temperature section is 540℃~580℃, and the furnace time in the low-temperature section is 1.8 min / mm ~ 3.0 min / mm; the temperature of the high-temperature section is 860℃~900℃, and the furnace time in the high-temperature section is 0.8 min / mm ~ 1.4 min / mm; the temperature of the cooling section is 740℃~780℃, and the furnace time in the cooling section is 0.6 min / mm ~ 1.0 min / mm.

5. The method for preparing wear-resistant steel according to claim 4, characterized in that: After the steel plate comes out of the quenching heat treatment furnace, it directly enters the roller press quenching machine for further quenching. The average cooling rate of quenching is 9℃ / s ~ 52℃ / s, and the final quenching temperature is 120℃ ~ 280℃.

6. The method for preparing wear-resistant steel according to claim 5, characterized in that: In the tempering process, the heating temperature is 200℃~260℃, and the tempering holding time is 4.0 min / mm~6.0 min / mm.

7. A wear-resistant steel resistant to corrosion by acidic mine water in coal mines, characterized in that: It is prepared by any one of the methods of claims 1-6.

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