High-strength, tough, and wear-resistant alloy steel and its preparation method

Abstract

A high-strength, high-toughness, and wear-resistant alloy steel and its preparation method are disclosed, belonging to the field of wear-resistant materials technology. The method employs a medium-frequency induction furnace for melting. First, ordinary scrap steel, a carbon raiser, ferroniobium, copper plates, and ferrochrome are mixed and heated in the furnace until the molten steel is clear. Then, ferrosilicon and ferromanganese are added sequentially, followed by aluminum blocks. Four to six minutes after the aluminum blocks are added, ferroboron is finally added. The molten steel is fed through a metal-coated wire outside the furnace to improve its quality. During the casting process, a mixture containing lanthanum, cerium, rare earth ferrosilicon powder, and pure iron powder is added in slurry to further refine the solidification structure of the steel. After quenching and tempering heat treatment, the obtained wear-resistant alloy steel exhibits high hardness and strength, good toughness, and excellent wear resistance. Its widespread application has significant economic and social benefits.

Description

Technical Field

[0001] This invention relates to a wear-resistant alloy steel and its preparation method, and particularly to a high-strength and high-toughness wear-resistant alloy steel and its preparation method, belonging to the field of wear-resistant materials technology. Background Technology

[0002] During ore mining, crushing, and grinding, mechanical components often face harsh service conditions. Materials frequently fail prematurely due to insufficient wear resistance, leading to serious economic losses and safety issues. High-manganese steel and high-chromium cast iron are commonly used wear-resistant materials. High-manganese steel only exhibits excellent wear resistance after work hardening under strong impact conditions. High-chromium cast iron contains a large amount of brittle carbides; although it has high hardness and wear resistance, it is prone to fracture failure under strong impact. Currently used martensitic wear-resistant steels have high strength and hardness, but low toughness, making them unsuitable for the service requirements of mining machinery. Therefore, developing high-strength, high-hardness, high-toughness, and high-wear-resistant alloy steels is of paramount importance.

[0003] Chinese invention patent CN116926431A discloses a high-strength, high-toughness NM450 wear-resistant steel plate and its production method. The chemical composition of the steel, by weight percentage, is C = 0.18%–0.21%, Si = 0.15%–0.40%, Mn = 1.05%–1.25%, P ≤ 0.012%, S ≤ 0.003%, Cr = 0.65%–0.80%, and Ni = 0.40%–0.45%. The composition is as follows: Nb = 0.020%–0.030%, Ti = 0.012%–0.030%, Al = 0.050%–0.090%, B = 0.0014%–0.0030%, H ≤ 0.0002%, N ≤ 0.0060%, O ≤ 0.0015%, with the remainder being Fe and unavoidable impurities. The process steps include converter smelting, LF refining, vacuum degassing, continuous casting, heating, rolling, and heat treatment. The produced wear-resistant steel plate has a surface hardness of 420–480 HBW, yield strength ≥ 1200 MPa, tensile strength ≥ 1400 MPa, elongation ≥ 12%, and meets the requirements for 3a 90° radius cold bending and 0℃ impact resistance. kv ≥60J, -20℃ impact A kv ≥50J, -40℃ impact A kv≥35J. Chinese invention patent CN116904836A also discloses a method for preparing high-hardness, high-toughness bainitic wear-resistant steel, characterized by the following steps: (1) weighing raw materials according to the weight percentage of the chemical composition of the high-hardness, high-toughness bainitic wear-resistant steel, and then smelting and casting them into a billet; the high-hardness, high-toughness bainitic wear-resistant steel includes the following chemical composition by weight percentage: C: 0.3-0.33%, Si: 1.0-1.4%, Mn: 0.6-0.7%, Cr: 0.9-1.0%, P<0.007%, S<0.001%, Ti: 0.3-0.4%, Ni: 1.3 -1.5%, Mo: 0.3-0.5%, B: 0.001-0.002%, balance is Fe and unavoidable impurities; (2) heat the billet and keep it warm for a period of time, then heat it up and keep it warm and then cool it down for forging, and then air cool it to room temperature; (3) heat the steel obtained in step (2) and keep it warm and then cool it down for the first time. After the rolling is completed, heat it up and run it for the second time, and then air cool it to room temperature; (4) heat the rolled steel, keep it warm for a period of time, air cool it to room temperature, then quench it to below zero and keep it cold for a period of time, then heat it up and keep it warm for a period of time, and then air cool it to room temperature to obtain high hardness and high toughness bainitic wear-resistant steel. Chinese invention patent CN116904860A also discloses a novel wear-resistant steel and its manufacturing method. It is prepared from the following raw materials by mass percentage: C: 0.12–0.18%, Si: 1.10–1.30%, Mn: 1.60–1.90%, S≤0.005%, P≤0.015%, Ti: 0.10–0.15%, Al: 0.30–0.50%, N≤0.0050%, with the remainder being Fe and unavoidable impurity elements. This invention provides a novel wear-resistant steel and its manufacturing method that changes the existing online rolling method for strengthening wear-resistant steel by relying on hard-phase martensite. By introducing economical, high-hardness TiC particles into the microstructure, the wear resistance of the steel plate is enhanced, and the strength is appropriately reduced. This results in lower steel plate stress and easier plate shape control. The novel wear-resistant steel produced by this invention and its method has a tensile strength Rm≥950MPa, a yield strength of 550MPa≤Rel≤850MPa, HBW≥270HB, and an elongation A50≥12%. It exhibits excellent wear resistance, a simple production process, and is mainly used in the bodies of special-purpose vehicles, making it highly valuable for widespread application. Chinese invention patent CN115505826A also discloses a method for preparing high-toughness TiC particle-reinforced martensitic wear-resistant steel plates using rare earth modification treatment. This method includes smelting, casting, heating of continuously cast billets, rolling, cooling, and heat treatment, wherein the steel contains Ce: 0.001%-0.006%.This invention fully utilizes the Ce element in inexpensive rare earth alloys to purify molten steel and effectively reduce or eliminate the segregation of P and S at grain boundaries; it forms rare earth composite particles, which modify TiC particles and improve the toughness of TiC particle-reinforced martensitic wear-resistant steel plates; the resulting steel plates have a hardness of 400-500 HB, a tensile strength of 1400-1600 MPa, an elongation of 10%-13%, an impact absorption energy of over 35 J at -20℃, and wear resistance more than 1.5 times that of traditional wear-resistant steels of the same hardness. Chinese invention patent CN114763592A also discloses a low-cost, high-wear-resistant steel, which, in addition to Fe and unavoidable impurity elements, contains the following chemical elements in the following mass percentages: 0.75% ≤ C ≤ 2.2%, 0 < Si ≤ 0.2%, 0 < Mn ≤ 0.2%, 0.1% ≤ Al ≤ 0.5%; the matrix of the wear-resistant steel is martensite, with cementite particles uniformly distributed on the martensitic matrix. Furthermore, the invention also discloses a method for manufacturing the aforementioned wear-resistant steel, which includes the following steps: (1) smelting and casting; (2) heating; (3) rolling; (4) cooling: first cooling to below 400°C at a cooling rate of ≤5°C / s, then heating to enter the austenite-cementite two-phase region, and then cooling to room temperature at a cooling rate of 10-100°C / s. However, the above inventions all require rolling to produce wear-resistant steel products, which involves complex processes, high energy consumption, and cannot process wear-resistant parts with complex shapes and sizes.

[0004] Chinese invention patent CN116695002A discloses a high-hardness, high-toughness wear-resistant steel ball and its preparation process. The elemental composition and weight ratio of the wear-resistant steel ball are as follows (by specific gravity): C: 0.95-1.1%; Si: 0.1-0.4%; Mn: 0.1-0.4%; S: 0.1-0.3%; P: 0.1-0.3%; Cr: 15.0-20.0%; Ni: 1.0-1.5%; Mo: 0.9-1.1%; V: 0.3-0.6%; Nb: 0.2-0.4%; Re: 0.02-0.04%; Cu: 0.7-1.1%, with the balance being Fe and unavoidable impurities. The wear-resistant steel balls prepared by this invention, which are forged using chromium and carbon as the base materials and supplemented with tungsten, manganese, niobium and other metal raw materials in a certain proportion, have good high hardness, high impact resistance and high toughness. They can effectively improve the consistency of surface and internal hardness, wear resistance and smoothness of the steel balls, making them suitable for various fields and allowing for better promotion and use. Chinese invention patent CN116926423A also discloses a low-cost wear-resistant steel NM400 and its production method. Its chemical composition and mass content are as follows: C: 0.15–0.18%, Si: 0.10–0.20%, Mn: 1.20–1.30%, P≤0.009%, S≤0.003%, Cr: 0.35–0.45%, Ti: 0.010–0.020%, Nb: 0.015–0.025%, Als: 0.030–0.040%, B: 0.0010–0.0018%, H≤0.00012%, N≤0.0040%, with the remainder being Fe and unavoidable trace impurities. The production method includes steelmaking, controlled rolling and cooling, and quenching + tempering heat treatment processes. This invention does not add Mo, employs a large water volume and high water ratio in the quenching cooling process, and uses stacked heating and low-temperature tempering in the tempering process, resulting in NM400 with excellent mechanical properties. Chinese invention patent CN116770177A also discloses a low-cost, high-strength wear-resistant steel with a nano-bainitic structure and its preparation method. The chemical composition of the nano-bainitic low-cost, high-strength wear-resistant steel, in mass percentages, is as follows: C: 0.4-0.9%, Si: 1.3-2.5%, Mn: 0.7-2.4%, Cr: 0.5-1.4%, Al: 0.8-2.5%, S≤0.01%, P≤0.01%, with the remainder being Fe and unavoidable impurities. The preparation method includes ingot preparation, forging into billets, spheroidizing annealing, isothermal quenching, and testing and analysis. This invention can synergistically improve wear resistance, room temperature impact toughness, and strength, and has important guiding significance for the industrial production of low-cost ultra-high-strength wear-resistant steel. The above invention requires forging or rolling, which is a complex process with high energy consumption, and cannot process wear-resistant parts with complex shapes and sizes.

[0005] Chinese invention patent CN116254480A discloses a V-Ti wear-resistant steel with a hardness of HB550-600. Its chemical composition and wt% are: C: 0.25-0.45%, Mn: 0.80-1.20%, Gr+Mo: 0.55-0.95%, V+Ti: 0.25-0.44%, P≤0.015%, S≤0.0025%, N≤0.0045%, O≤0.0015%. The production method is as follows: smelting in a converter followed by LF refining; RH vacuum treatment; continuous casting to form a billet; billet heating; rough rolling in the recrystallization zone; finish rolling in the non-recrystallization zone; cooling; offline quenching; low-temperature tempering; ready for use. This invention refines the V and Ti precipitates to 5–15 nm in size, with the 5–15 nm nanoscale precipitates accounting for 40–50% of the total precipitates. The tensile strength is ≥1900 MPa, the hardness is HB550–600, the elongation A is ≥7%, and the impact energy at -40℃ is ≥30 J, meeting the needs of high-end users. Chinese invention patent CN116752035A also discloses a 650HB grade wear-resistant steel plate and its preparation method. The chemical composition of the 650HB grade wear-resistant steel plate is as follows (mass percentage): C: 0.60–0.70%, Si≤0.6%, Mn: 1.5–2.5%, S≤0.005%, P≤0.010%, Cr: 1.5–2.5%, B: 0.0015–0.0035%, Ti: 0.08–0.12%, V: 2.0–3.0%, with the remainder being Fe and unavoidable impurities. The preparation method includes smelting, rolling, and heat treatment processes. This invention's wear-resistant steel does not require the use of expensive alloying elements such as Ni, Mo, and Nb. After heat treatment, its microstructure consists of tempered martensite, with a surface Brinell hardness ≥650 HBW, a core Brinell hardness ≥630 HBW, and an impact energy ≥30 J at -40℃, exhibiting excellent comprehensive mechanical properties. Chinese invention patent CN116024403A also discloses a method for improving the wear resistance of low-alloy wear-resistant steel through rare earth treatment. The method involves adding rare earth alloys to the molten steel during the RH vacuum refining process, achieving a La and / or Ce mass percentage of 0.0005-0.0100%. The production process for the low-alloy wear-resistant steel is: hot metal pretreatment → converter smelting → LF refining → RH vacuum refining → continuous casting → hot rolling → heat treatment. The rare earth alloy is one or more of the following: lanthanum-iron alloy, cerium-iron alloy, lanthanum-cerium-iron alloy, and lanthanum-cerium alloy cored wire. The method of adding rare earth alloy is as follows: during the vacuum treatment process in the RH vacuum refining process, rare earth alloy is added through a high-level alloy silo, or during the repressing process in the RH vacuum refining process, rare earth alloy cored wire is fed in using a wire feeder.Chinese invention patent CN114351053A also discloses an ultrafine-grained high-toughness wear-resistant steel and its manufacturing method. The composition of the steel by weight percentage is as follows: C: 0.32-0.40%, Si: 0.9-1.7%, Mn: 2.5-4.0%, P: ≤0.015%, S: ≤0.008%, Mo: 0.20-0.40%, Ni: 1.3-2.0%, Ti: 0.45-0.55%, Als: 0.015-0.05%, N≤0.010%, O≤0.0030%, H≤0.00020%, with the balance being Fe and unavoidable impurities. The manufacturing method includes smelting, casting, rolling, and heat treatment. Steel plates produced using this invention exhibit a yield strength of 1006–1221 MPa, a tensile strength of 1319–1497 MPa, a surface hardness of 467–461 HBW, a core hardness of 448–488 HBW, with the core hardness not less than 95% of the surface hardness, and an impact energy ≥24 J at -20℃. However, the aforementioned inventions all require rolling methods to produce wear-resistant steel products, which is not only complex and energy-intensive but also cannot process wear-resistant parts with complex shapes and dimensions.

[0006] Chinese invention patent CN116926437A discloses a high-strength low-alloy wear-resistant steel and its preparation method. The chemical composition of the high-strength low-alloy wear-resistant steel, by mass fraction, includes: C: 0.28-0.38%, Mn: 1.2-1.5%, Si: 1.6-2.2%, Cr+Mo < 1%, V: 0.005-0.015%, rare earth Re: 0.002-0.01%, S ≤ 0.03%, P ≤ 0.03%, with the balance being iron and unavoidable impurities. This invention, through low-cost alloying combined with multiple simple heat treatments, enables the low-alloy wear-resistant steel to obtain a high proportion of martensitic structure, exhibiting high strength, high hardness, and good toughness, meeting the requirements of wear-resistant parts such as bucket teeth in engineering machinery. The high-strength low-alloy wear-resistant steel of this invention has a hardness ≥ 52 HRC, a room temperature impact absorption energy (V-notch) ≥ 16 J, and a tensile strength ≥ 1800 MPa. Chinese invention patent CN116254390A also discloses a high-performance low-carbon wear-resistant steel and a heat treatment method for improving the performance of low-carbon wear-resistant steel. The heat treatment method for improving the performance of low-carbon wear-resistant steel includes the following steps: S1: heating the low-carbon wear-resistant steel to 530-570℃ and holding it at that temperature, then performing pulse treatment; S2: heating the pulse-treated low-carbon wear-resistant steel to 900-940℃ and holding it at that temperature, then performing pulse treatment, followed by water quenching; S3: heating and holding the water-quenched low-carbon wear-resistant steel at that temperature, then performing pulse treatment, and finally performing water quenching. This invention fully considers the synergistic strengthening mechanism of fine grain strengthening, precipitation strengthening, and solid solution strengthening in its composition design and heat treatment process. Simultaneously, the novel heat treatment method of applying electric pulses ensures that the wear-resistant steel has sufficient toughness, giving the low-carbon wear-resistant steel sufficient strength and hardness, ensuring good wear resistance while possessing high toughness. Chinese invention patent CN114231856A also discloses a micron-sized carbide-reinforced low-density wear-resistant steel, its preparation method, and its application. The chemical composition of the micron-sized carbide-reinforced low-density wear-resistant steel is as follows (mass percentage): C: 1.2-1.8%, Mn: 18.0-20.5%, Cr: 1.5-2.5%, Al: 12.0-16.0%, Si: 0.3-0.8%, Zr: 0.01-0.06%, B: 0.006-0.01%, N: 0.003-0.01%, rare earth elements: 0.01-0.03%, S≤0.04%, P≤0.04%, with the remainder being iron and unavoidable impurities. It is obtained through medium-frequency electric furnace smelting, casting via deoxidation and rare element synergistic modification process, and short-process medium-temperature heat treatment. Its microstructure contains a high volume fraction of micron-sized carbide reinforcing phase. The wear-resistant steel of this invention exhibits excellent resistance to abrasive wear. Chinese invention patent CN114231851A also discloses a nano-carbide reinforced wear-resistant steel, its preparation method and application, which belongs to the field of wear-resistant steel technology.Its chemical composition by mass percentage is as follows: C: 1.35-2.05%, Mn: 12.0-21.0%, Al: 4.0-7.0%, Si: 1.2-1.8%, V: 0.05-0.2%, W: 0.05-0.2%, N: 0.003-0.01%, rare earth: 0.01-0.03%, S≤0.04%, P≤0.04%, with the remainder being iron and unavoidable impurities. The above-mentioned wear-resistant steel is obtained by smelting in a medium-frequency electric furnace, casting through deoxidation and rare earth modification processes, and undergoing a multi-pass precipitation strengthening heat treatment process. The microstructure of the nano-carbide-reinforced wear-resistant steel contains a large number of nano-carbide hard phases. The wear-resistant steel of this invention also exhibits good wear resistance under complex stress impact wear conditions. However, the above invention only uses heat treatment to obtain precipitation strengthening carbides, resulting in a small amount of strengthening phase and limited improvement in wear resistance.

[0007] Chinese invention patent CN109518088A discloses a method for spontaneously reinforcing the wear resistance of wear-resistant steel. The method is characterized by the following preparation process: the alloy composition of the spontaneously reinforced wear-resistant steel is as follows: B: 0.01–0.03%; N: 0.03–0.06%; Nb: <0.02%; Ti: <0.001%; ​​Al: <0.05%; V: <0.1%. The C, Si, Mn, Cr, and Mo elements in the steel can be added as required. Adjustments are made up of Fe and impurities, the impurities being: P≤0.01%; S≤0.001%; ​​Cu≤0.02%; the preparation steps are as follows: (1) The casting is melted and cast in a vacuum induction furnace, and the casting cooling rate is 5~20℃ / min; (2) The maximum heating temperature in the heat treatment process after the wear-resistant steel is formed is ≤1200℃, and it is kept warm for a period of time, and then cooled to room temperature by water or oil; (3) Based on the maximum wall thickness of the wear-resistant steel, the holding time is ≤1h for every 10mm. Chinese invention patent CN108950432A also discloses a high-strength, high-toughness low-alloy wear-resistant steel, whose raw material formula by percentage is as follows: carbon (C) 0.25-0.35%, manganese (Mn) 1.2-1.8%, silicon (Si) 0.45-0.55%, chromium (Cr) 1.0-1.5%, nickel (Ni) 0.6-0.8%, molybdenum (Mo) 0.4-0.6%, boron 0.002-0.003%, rare earth elements 0.02-0.06%, with the remainder being iron (Fe) and unavoidable impurity elements. This invention also discloses a method for manufacturing this high-strength, high-toughness low-alloy wear-resistant steel. This invention, containing trace amounts of boron and rare earth elements, uses heat treatment and excellent casting processes to achieve low-alloy wear-resistant steel with high strength (tensile strength greater than 1300 MPa) and hardness (approximately 40 HRC). Chinese invention patent CN108220811A also discloses a wear-resistant steel and its preparation method. The wear-resistant steel of this invention is composed of the following components by mass percentage: C 0.40–0.46%, Si 0.30–0.50%, Mn 1.8–2.4%, Cr 0.9–1.4%, Ni 0.3–0.5%, Mo 0.2–0.3%, Al 0.1–0.2%, Nb 0.01–0.02%, B 0.03–0.05%, Cu 0.01–0.03%, N 0.07–0.15%, with the balance being Fe and unavoidable impurities. However, the above-mentioned wear-resistant material still suffers from low hardness and poor wear resistance. Summary of the Invention

[0008] To overcome the aforementioned shortcomings of wear-resistant alloy steel, this invention adds trace amounts of high-hardness nano-BN to medium-carbon alloy steel. To improve the uniformity of nano-BN distribution in the steel, magnesium is also added, and lanthanum and cerium rare earth elements are added during the casting process. Finally, by improving the heat treatment process, the strength, toughness, and wear resistance of the wear-resistant alloy steel are significantly improved.

[0009] A high-strength, high-toughness, and wear-resistant alloy steel and its preparation method are described below.

[0010] ① A medium-frequency induction furnace is used to melt steel. First, ordinary scrap steel, carbon raiser, ferroniobium, copper plate and ferrochrome are put into the furnace and mixed and heated to melt. After the steel is melted, ferrosilicon and ferromanganese are added in sequence. The steel in the furnace is heated to 1589-1612℃. Then aluminum blocks are added. After adding the aluminum blocks for 4-6 minutes, ferroboron is added last. The chemical composition and mass fraction of the steel in the furnace are controlled at 0.38-0.47%C and 0.33-0. The composition is as follows: 40% Cu, 0.83-0.96% Si, 1.17-1.34% Mn, 0.04-0.07% Nb, 0.022-0.041% Al, 0.0026-0.065% B, 2.66-2.85% Cr, ≤0.04% S, ≤0.05% P, with the balance being Fe and unavoidable impurities; the molten steel is then heated to 1642-1655℃ and poured into a ladle.

[0011] ② After all the molten steel has entered the ladle, metal-core wire is added to the molten steel using a wire feeding method. The amount of metal-core wire added is 2-3 kg / ton of molten steel. The method for making metal-core wire is to first mix 30-50 mesh magnesium powder, nano BN powder, 60-80 mesh ferrotitanium powder, and 30-50 mesh calcium powder evenly. The mass composition of magnesium powder, nano BN powder, ferrotitanium powder, and calcium powder are 15-18%, 25-28%, 30-32%, and 25-27%, respectively, and the total mass composition of magnesium powder, nano BN powder, ferrotitanium powder, and calcium powder is 100%. Then, the evenly mixed powder is packaged in a 0.25-0.29 mm thick low-carbon mild steel strip and rolled into a metal-core wire with a diameter of φ4.5-6.0 mm on an alloy cored wire mill.

[0012] ③ After the metal cored wire has completely melted in the molten steel for 3-4 minutes, the slag is removed and the molten steel is allowed to stand. When the temperature of the molten steel in the ladle drops to 1519-1536℃, the molten steel is poured into the mold. During the pouring process, a mixture containing lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder is added along with the flow. The size of the lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder is 0.3-0.8mm. The amount of lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder added accounts for 0.10-0.15% and 0.5-0.6% of the mass fraction of the molten steel entering the mold, respectively.

[0013] ④ After the molten steel in the mold solidifies, the casting is removed from the mold, polished and cleaned of sand, and then heated in the furnace to 880-910℃. After holding at this temperature for 1.5-2.5 hours, the surface of the casting is cooled to 220-280℃ using a spray cooling method, with the cooling rate controlled at 30-42℃ / s. Then, it is heated in the furnace to 320-340℃ and held for 8-10 hours. After the furnace is cooled to below 120℃, the casting is removed from the furnace and air-cooled to room temperature to obtain high-strength, tough, and wear-resistant alloy steel.

[0014] The chemical composition and mass fraction of the titanium iron powder mentioned in step ② are: 68.33-71.47% Ti, <0.5% Al, <0.10% Si, <0.20% Mn, <0.20% C, <0.03% P, <0.03% S, <0.50% V, with the balance being Fe and unavoidable impurities.

[0015] The chemical composition and mass fraction of the lanthanum-cerium rare earth ferrosilicon powder mentioned in step ③ are: 36.22-37.68% La+Ce, 43.88-46.02% Si, <2.0% Ba, <2.0% Ca, <1.5% Al, <0.3% Ti, <0.5% Mn, with the balance being Fe and unavoidable impurities.

[0016] This invention relates to a high-strength, tough, and wear-resistant alloy steel and its preparation method, which uses a medium-frequency induction furnace to melt molten steel, resulting in a simple process and high production efficiency. First, ordinary scrap steel, carbon raiser, ferroniobium, copper plates, and ferrochrome are mixed and heated in a furnace until melted. After the molten steel is clear, ferrosilicon and ferromanganese are added in sequence, and the molten steel in the furnace is heated to 1589-1612℃. Then, aluminum blocks are added. After 4-6 minutes of adding the aluminum blocks, ferroboron is added last. The chemical composition and mass fraction of the molten steel in the furnace are controlled as follows: 0.38-0.47% C, 0.33-0.40% Cu, 0.83-0.96% Si, 1.17-1.34% Mn, 0.04-0.07% Nb, 0.022-0.041% Al, 0.0026-0.0065% B, 2.66-2.85% Cr, ≤0.04% S, ≤0.05% P, with the balance being Fe and unavoidable impurities. Then, the molten steel is heated to 1642-1655℃ and then poured into a ladle. Using the above method to smelt steel significantly reduces the oxidation loss of elements such as silicon, manganese, aluminum, and boron, thereby improving the yield of alloying elements. The wear-resistant alloy steel of this invention contains 0.83-0.96% Si, 1.17-1.34% Mn, and 2.66-2.85% Cr, which significantly improves the wear resistance of the alloy and facilitates the formation of a bainitic + martensite composite structure, resulting in a significant improvement in the wear resistance and strength of the steel. The addition of 0.33-0.40% Cu and 0.0026-0065% B significantly improves the hardenability of the steel. The addition of 0.0026-0065% B also improves the hardenability of the steel. The addition of 0.04-0.07% Nb facilitates the combination with titanium in the subsequently added ferrotitanium tinplate, generating high-hardness (Nb,Ti)C particles, thus improving the wear resistance of the alloy steel.

[0017] In this invention, after all the molten steel has entered the ladle, a metal-cored wire is added to the molten steel using a wire feeding method. The amount of metal-cored wire added is 2-3 kg / ton of molten steel. The method for manufacturing the metal-cored wire is to first mix 30-50 mesh magnesium powder, nano-BN powder, 60-80 mesh ferrotitanium powder, and 30-50 mesh calcium powder evenly. The chemical composition and mass fraction of the ferrotitanium powder are: 68.33-71.47% Ti, <0.5% Al, <0.10% Si, <0.20% Mn, <0.20% C, <0.03% P, <0.03% S, <0.50% V, with the balance being Fe and non-ferrous metals. Impurities to be avoided; the mass composition of metallic magnesium powder, nano-BN powder, ferrotitanium powder, and metallic calcium powder are 15-18%, 25-28%, 30-32%, and 25-27%, respectively, with the total mass composition of metallic magnesium powder, nano-BN powder, ferrotitanium powder, and metallic calcium powder being 100%; the uniformly mixed powders are then packaged in low-carbon mild steel strips with a thickness of 0.25-0.29 mm and rolled into metal cored wires with a diameter of φ4.5-6.0 mm on an alloy cored wire mill. The alloying elements are added using a wire feeding method, which ensures good safety and high alloying element recovery. This invention incorporates trace amounts of nano-BN powder with high hardness and good thermal stability into the steel. Boron nitride (BN) is composed of nitrogen and boron atoms, and its crystal structure is a hexagonal, graphite-like layered structure. The electronegativity difference between nitrogen and boron atoms in the boron nitride molecule is greater than that between carbon and nitrogen atoms, thus making the bonds in boron nitride more stable. This crystal structure and more stable bond energy result in high boron nitride hardness. The addition of nano-BN powder can significantly improve the wear resistance of steel. However, nano-BN powder is prone to agglomeration and has low density, making it easy to float in molten steel. This invention adds nano-BN powder and magnesium powder simultaneously to molten steel via a wire feeding method. Magnesium has low melting and boiling points, and when added to molten steel, it easily vaporizes under the action of high-temperature molten steel, promoting the stirring of the molten steel and facilitating the uniform distribution of nano-BN in the steel. In addition, the addition of magnesium and metallic calcium powder has excellent deoxidation, desulfurization, and dephosphorization effects, and calcium also has a beneficial effect on improving the morphology of inclusions in steel, thereby significantly improving the toughness of the steel.

[0018] In this invention, after the metal-core wire is completely melted in molten steel for 3-4 minutes, slag is removed, and the molten steel is allowed to stand. When the temperature of the molten steel in the ladle drops to 1519-1536℃, the molten steel is poured into a mold. During the pouring process, a mixture containing lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder is added along with the flow. The chemical composition and mass fraction of the lanthanum, cerium, rare earth, ferrosilicon powder are: 36.22-37.68% La + Ce, 43.88-46.02% Si, <2.0% Ba, <2.0% Ca, <1.5% Al, <0.3% Ti, <0.5% Mn, with the balance being Fe and unavoidable impurities. The size of the lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder is 0.3-0.8 mm; the amount of lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder added accounts for 0.10-0.15% and 0.5-0.6% of the mass fraction of the molten steel entering the mold, respectively. After the molten steel undergoes magnesium-calcium deoxidation, lanthanum and cerium rare earth elements are added to the steel. Lanthanum and cerium rare earth elements are mainly dissolved into the steel. Since the atomic radii of La and Ce in the steel are much larger than those of Fe, and the equilibrium distribution coefficients of La and Ce are much less than 1, La and Ce atoms tend to accumulate at the solid-liquid interface during solidification, increasing the number of nuclei and promoting significant refinement of the solidification structure, which is beneficial to significantly improving the strength and toughness of the steel.

[0019] After the molten steel in the mold of this invention solidifies, the casting is removed from the mold, polished and cleaned of sand, and then heated in a furnace to 880-910℃. After holding at this temperature for 1.5-2.5 hours, austenitization is achieved. The surface of the casting is then cooled to 220-280℃ using a spray cooling method, with the cooling rate controlled at 30-42℃ / s. This prevents the formation of low-hardness pearlite and ferrite phases and avoids quenching cracks. The casting is then further heated in the furnace to 320-340℃ and held for 8-10 hours. After furnace cooling to below 120℃, the dispersion precipitation of nano-sized (Nb,Ti)C is facilitated, further improving the wear resistance of the steel. Finally, the casting is air-cooled to room temperature to obtain a wear-resistant alloy steel with low internal stress and high strength and toughness.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The high-strength, tough, and wear-resistant alloy steel of this invention has readily available raw materials and does not contain expensive alloying elements such as molybdenum, nickel, vanadium, and tungsten, resulting in low production costs.

[0022] (2) The high-strength, tough, and wear-resistant alloy steel of the present invention has a simple preparation process, a short production process, high efficiency, and low energy consumption;

[0023] (3) The high-strength, toughness and wear-resistant alloy steel of this invention has high hardness, good strength and toughness, with a hardness greater than 60HRC and an impact toughness greater than 80J / cm. 2 It has a tensile strength greater than 1500MPa, a yield strength greater than 1100MPa, and excellent comprehensive mechanical properties;

[0024] (4) The high-strength, high-toughness, and wear-resistant alloy steel of this invention has excellent wear resistance. Under laboratory dynamic load impact wear test conditions, its wear resistance is more than 5 times higher than that of high-manganese steel and more than 3 times higher than that of ordinary martensitic wear-resistant alloy steel. Ball mill liners, crusher tooth plates, and crusher hammers made with the material of this invention, under the same working conditions, are 4 times, 6 times, and 7 times higher than those made with ordinary martensitic wear-resistant alloy steel ball mill liners, high-manganese steel crusher tooth plates, and high-manganese steel crusher hammers, respectively. Its widespread application has good economic and social benefits.

[0025] (5) The present invention can be prepared into any structure according to the shape requirements of the product. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0027] Example 1:

[0028] A high-strength, high-toughness, and wear-resistant alloy steel and its preparation method are characterized by smelting in a medium-frequency induction furnace. The specific preparation process steps are as follows:

[0029] ① A 1000 kg medium-frequency induction furnace is used to melt steel. First, ordinary scrap steel, carbon raiser, ferroniobium, copper plate, and ferrochrome are mixed and heated in the furnace until the steel is clear. Then, ferrosilicon and ferromanganese are added in sequence to heat the molten steel in the furnace to 1612℃. Then, aluminum blocks are added. Four minutes after the aluminum blocks are added, ferroboron is added last. The chemical composition and mass fraction of the molten steel in the furnace are controlled at 0.44% C, 0.38% Cu, 0.87% Si, 1.26% Mn, 0.05% Nb, 0.029% Al, 0.0047% B, 2.70% Cr, 0.028% S, 0.035% P, with the balance being Fe and unavoidable impurities. Then, the molten steel is heated to 1648℃ and then tapped into a ladle.

[0030] ② After all the molten steel has entered the ladle, a metal-cored wire is added to the molten steel using a wire feeding method. The amount of metal-cored wire added is 2.5 kg / ton of molten steel. The method for manufacturing the metal-cored wire is to first mix 30-50 mesh magnesium powder, nano-BN powder, and 60-80 mesh ferrotitanium powder (the chemical composition and mass fraction of the ferrotitanium powder are: 70.23% Ti, 0.15% Al, 0.07% Si, 0.12% Mn, 0.15% C, 0.029% P, 0.014% S). 0.26% V (balance: Fe and unavoidable impurities) and 30-50 mesh metallic calcium powder are mixed evenly; the mass composition of metallic magnesium powder, nano BN powder, ferrotitanium powder and metallic calcium powder are 17%, 26%, 31% and 26% respectively, and the total mass composition of metallic magnesium powder, nano BN powder, ferrotitanium powder and metallic calcium powder is 100%; the above powders are then packaged in 0.27mm thick low carbon mild steel strip and rolled into φ5.0mm diameter metallic cored wire on an alloy cored wire unit;

[0031] ③ After the metal-core wire has completely melted in the molten steel for 3.5 minutes, the slag is removed and the molten steel is allowed to stand. When the temperature of the molten steel in the ladle drops to 1529℃, the molten steel is poured into the mold. During the pouring process, a mixture containing lanthanum, cerium, rare earth, and ferrosilicon powder (the chemical composition and mass fraction of the lanthanum, cerium, rare earth, and ferrosilicon powder are: 36.81% La + Ce, 45.07% Si, 1.24% Ba, 0.63% Ca, 1.18% Al, 0.22% Ti, 0.16% Mn, with the balance being Fe and unavoidable impurities) and pure iron powder is added. The size of the lanthanum, cerium, rare earth, and ferrosilicon powder and the pure iron powder are 0.3-0.8 mm. The amount of lanthanum, cerium, rare earth, and ferrosilicon powder and the pure iron powder added accounts for 0.12% and 0.55% of the mass fraction of the molten steel entering the mold, respectively.

[0032] ④ After the molten steel in the mold solidifies, the casting is removed from the mold, ground and cleaned of sand, then heated in a furnace to 900℃. After holding at that temperature for 2 hours, the surface of the casting is cooled to 240-260℃ using a spray cooling method, with the cooling rate controlled at 35-39℃ / s. Subsequently, it is heated in the furnace to 330℃ and held for 9 hours. After furnace cooling to below 120℃, it is removed from the furnace and air-cooled to room temperature to obtain high-strength, tough, and wear-resistant alloy steel. The mechanical properties of the alloy steel are tested according to national standards; specific mechanical properties are shown in Table 1.

[0033] Example 2:

[0034] A high-strength, high-toughness, and wear-resistant alloy steel and its preparation method are characterized by smelting in a medium-frequency induction furnace. The specific preparation process steps are as follows:

[0035] ① A 3000 kg medium-frequency induction furnace is used to melt steel. First, ordinary scrap steel, carbon raiser, ferroniobium, copper plates, and ferrochrome are mixed and heated in the furnace until the steel is clear. Then, ferrosilicon and ferromanganese are added in sequence to heat the molten steel in the furnace to 1589℃. Then, aluminum blocks are added. Six minutes after the aluminum blocks are added, ferroboron is added last. The chemical composition and mass fraction of the molten steel in the furnace are controlled at 0.38% C, 0.40% Cu, 0.83% Si, 1.34% Mn, 0.04% Nb, 0.041% Al, 0.0026% B, 2.85% Cr, 0.036% S, 0.044% P, with the balance being Fe and unavoidable impurities. Then, the molten steel is heated to 1642℃ and then tapped into a ladle.

[0036] ② After all the molten steel has entered the ladle, a metal-cored wire is added to the molten steel using a wire feeding method. The amount of metal-cored wire added is 2 kg / ton of molten steel. The method for manufacturing the metal-cored wire is to first mix 30-50 mesh magnesium powder, nano-BN powder, and 60-80 mesh ferrotitanium powder (the chemical composition and mass fraction of the ferrotitanium powder are: 68.33% Ti, 0.31% Al, 0.08% Si, 0.13% Mn, 0.14% C, 0.025% P, 0.028% S, 0. The powder is mixed with 30-50 mesh metallic calcium powder (0.21% V, balance Fe and unavoidable impurities) until uniform; the mass composition of metallic magnesium powder, nano BN powder, ferrotitanium powder and metallic calcium powder is 15%, 28%, 30% and 27% respectively, and the total mass composition of metallic magnesium powder, nano BN powder, ferrotitanium powder and metallic calcium powder is 100%; the uniformly mixed powder is then packaged in 0.25mm thick low carbon mild steel strip and rolled into φ4.5mm diameter metallic cored wire on an alloy cored wire unit;

[0037] ③ After the metal cored wire has completely melted in the molten steel for 3 minutes, the slag is removed and the molten steel is allowed to stand. When the temperature of the molten steel in the ladle drops to 1519℃, the molten steel is poured into the mold. During the pouring process, a mixture containing lanthanum, cerium, rare earth, and ferrosilicon powder (the chemical composition and mass fraction of the lanthanum, cerium, rare earth, and ferrosilicon powder are: 36.22% La + Ce, 46.02% Si, 0.82% Ba, 0.77% Ca, 0.35% Al, 0.11% Ti, 0.18% Mn, with the balance being Fe and unavoidable impurities) and pure iron powder is added. The size of the lanthanum, cerium, rare earth, and ferrosilicon powder and the pure iron powder are 0.3-0.8 mm. The amount of lanthanum, cerium, rare earth, and ferrosilicon powder and the pure iron powder added accounts for 0.10% and 0.6% of the mass fraction of the molten steel entering the mold, respectively.

[0038] ④ After the molten steel in the mold solidifies, the casting is removed from the mold, ground and cleaned of sand, then heated in a furnace to 880℃ and held for 2.5 hours. The surface of the casting is then cooled to 220-260℃ using a spray cooling method, with a cooling rate controlled at 30-35℃ / s. Subsequently, it is heated in the furnace to 320℃ and held for 10 hours. After furnace cooling to below 120℃, the casting is removed from the furnace and air-cooled to room temperature to obtain high-strength, tough, and wear-resistant alloy steel. The mechanical properties of the alloy steel are tested according to national standards; specific mechanical properties are shown in Table 1.

[0039] Example 3:

[0040] A high-strength, high-toughness, and wear-resistant alloy steel and its preparation method are characterized by smelting in a medium-frequency induction furnace. The specific preparation process steps are as follows:

[0041] ① A 1500 kg medium-frequency induction furnace is used to melt steel. First, ordinary scrap steel, carbon raiser, ferroniobium, copper plate, and ferrochrome are mixed and heated in the furnace until the steel is clear. Then, ferrosilicon and ferromanganese are added in sequence to heat the molten steel in the furnace to 1595℃. Then, aluminum blocks are added. Five minutes after the aluminum blocks are added, ferroboron is added last. The chemical composition and mass fraction of the molten steel in the furnace are controlled at 0.47% C, 0.33% Cu, 0.96% Si, 1.17% Mn, 0.07% Nb, 0.022% Al, 0.065% B, 2.66% Cr, 0.028% S, 0.039% P, with the balance being Fe and unavoidable impurities. Then, the molten steel is heated to 1655℃ and then tapped into the ladle.

[0042] ② After all the molten steel has entered the ladle, a metal-cored wire is added to the molten steel using a wire feeding method. The amount of metal-cored wire added is 3 kg / ton of molten steel. The method for manufacturing the metal-cored wire is to first mix 30-50 mesh magnesium powder, nano-BN powder, and 60-80 mesh ferrotitanium powder (the chemical composition and mass fraction of the ferrotitanium powder are: 71.47% Ti, 0.12% Al, 0.05% Si, 0.08% Mn, 0.03% C, 0.021% P, 0.014% S, 0. The powder is mixed evenly with 30-50 mesh metallic calcium powder (0.21% V, balance Fe and unavoidable impurities); the mass composition of metallic magnesium powder, nano BN powder, ferrotitanium powder and metallic calcium powder is 18%, 25%, 32% and 25% respectively, and the total mass composition of metallic magnesium powder, nano BN powder, ferrotitanium powder and metallic calcium powder is 100%; the evenly mixed powder is then packaged in a 0.29mm thick low carbon mild steel strip and rolled into a φ6.0mm diameter metallic cored wire on an alloy cored wire unit;

[0043] ③ After the metal cored wire has completely melted in the molten steel for 4 minutes, the slag is removed and the molten steel is allowed to stand. When the temperature of the molten steel in the ladle drops to 1536℃, the molten steel is poured into the mold. During the pouring process, a mixture containing lanthanum, cerium, rare earth, and ferrosilicon powder (the chemical composition and mass fraction of the lanthanum, cerium, rare earth, and ferrosilicon powder are: 37.68% La+Ce, 43.88% Si, 1.16% Ba, 1.05% Ca, 1.19% Al, 0.18% Ti, 0.38% Mn, with the balance being Fe and unavoidable impurities) and pure iron powder is added. The size of the lanthanum, cerium, rare earth, and ferrosilicon powder and the pure iron powder are 0.3-0.8 mm. The amount of lanthanum, cerium, rare earth, and ferrosilicon powder and the pure iron powder added accounts for 0.15% and 0.5% of the mass fraction of the molten steel entering the mold, respectively.

[0044] ④ After the molten steel in the mold solidifies, the casting is removed from the mold, ground and cleaned of sand, then heated in a furnace to 910℃ and held for 1.5 hours. The surface of the casting is then cooled to 260-280℃ using a spray cooling method, with the cooling rate controlled at 37-42℃ / s. Subsequently, it is heated in the furnace to 340℃ and held for 8 hours. After furnace cooling to below 120℃, it is removed from the furnace and air-cooled to room temperature to obtain high-strength, tough, and wear-resistant alloy steel. The mechanical properties of the alloy steel are tested according to national standards; specific mechanical properties are shown in Table 1.

[0045] Hardness testing was conducted in accordance with GB / T 230.1-2018 Metallic Materials Rockwell Hardness Test - Part 1: Test Methods.

[0046] The impact toughness test was conducted according to GB / T 229-2020, Charpy impact test method for metallic materials.

[0047] The strength test was conducted in accordance with GB / T 228.1-2010 Metallic materials, tensile testing, Part 1: Test method at room temperature.

[0048] Table 1 Mechanical properties of high-strength, toughness and wear-resistant alloy steel

[0049]

[0050] The high-strength, high-toughness, and wear-resistant alloy steel of this invention uses readily available raw materials, does not contain expensive alloying elements such as molybdenum, nickel, vanadium, and tungsten, and has low production costs. The preparation process of this high-strength, high-toughness, and wear-resistant alloy steel is simple, with a short production flow, high efficiency, and low energy consumption. This high-strength, high-toughness, and wear-resistant alloy steel has high hardness and good toughness, with a hardness greater than 60 HRC and an impact toughness greater than 80 J / cm². 2The high-strength, high-toughness, and wear-resistant alloy steel of this invention exhibits excellent wear resistance. Under laboratory dynamic load impact wear test conditions, its wear resistance is more than 5 times higher than that of high-manganese steel and more than 3 times higher than that of ordinary martensitic wear-resistant alloy steel. Ball mill liners, crusher tooth plates, and crusher hammers prepared using the material of this invention, under the same working conditions, show wear resistance improvements of 4 times, 6 times, and 7 times respectively compared to ordinary martensitic wear-resistant alloy steel ball mill liners, high-manganese steel crusher tooth plates, and high-manganese steel crusher hammers. The widespread application of this high-strength, high-toughness, and wear-resistant alloy steel can reduce the labor intensity of workers, increase the operating rate of mechanical equipment, and reduce material crushing costs, resulting in significant economic and social benefits.

Claims

1. A method for preparing a high-strength, high-toughness, and wear-resistant alloy steel, characterized in that, Melting is carried out using a medium-frequency induction furnace. The specific preparation process steps are as follows: ① A medium-frequency induction furnace is used to melt steel. First, ordinary scrap steel, carbon raiser, ferroniobium, copper plate and ferrochrome are put into the furnace and mixed and heated to melt. After the steel is melted, ferrosilicon and ferromanganese are added in sequence. The steel in the furnace is heated to 1589-1612℃. Then aluminum blocks are added. After adding the aluminum blocks for 4-6 minutes, ferroboron is added last. The chemical composition and mass fraction of the steel in the furnace are controlled at 0.38-0.47%C and 0.33-0. The composition is as follows: 40% Cu, 0.83-0.96% Si, 1.17-1.34% Mn, 0.04-0.07% Nb, 0.022-0.041% Al, 0.0026-0.065% B, 2.66-2.85% Cr, ≤0.04% S, ≤0.05% P, with the balance being Fe and unavoidable impurities; the molten steel is then heated to 1642-1655℃ and poured into a ladle. ② After all the molten steel has entered the ladle, metal-core wire is added to the molten steel using a wire feeding method. The amount of metal-core wire added is 2-3 kg / ton of molten steel. The method for making metal-core wire is to first mix 30-50 mesh magnesium powder, nano BN powder, 60-80 mesh ferrotitanium powder, and 30-50 mesh calcium powder evenly. The mass composition of magnesium powder, nano BN powder, ferrotitanium powder, and calcium powder are 15-18%, 25-28%, 30-32%, and 25-27%, respectively, and the total mass composition of magnesium powder, nano BN powder, ferrotitanium powder, and calcium powder is 100%. Then, the evenly mixed powder is packaged in a 0.25-0.29 mm thick low-carbon mild steel strip and rolled into a metal-core wire with a diameter of φ4.5-6.0 mm on an alloy cored wire mill. ③ After the metal cored wire has completely melted in the molten steel for 3-4 minutes, the slag is removed and the molten steel is allowed to stand. When the temperature of the molten steel in the ladle drops to 1519-1536℃, the molten steel is poured into the mold. During the pouring process, a mixture containing lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder is added along with the flow. The size of the lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder is 0.3-0.8mm. The amount of lanthanum, cerium, rare earth, ferrosilicon powder and pure iron powder added accounts for 0.10-0.15% and 0.5-0.6% of the mass fraction of the molten steel entering the mold, respectively. ④ After the molten steel in the mold solidifies, the casting is removed from the mold, ground and cleaned of sand, then heated in a furnace to 880-910℃ and held for 1.5-2.5 hours. The surface of the casting is then cooled to 220-280℃ using a spray cooling method, with a cooling rate controlled at 30-42℃ / s. Subsequently, it is heated in the furnace to 320-340℃ and held for 8-10 hours. High-strength, tough, and wear-resistant alloy steel can be obtained by cooling the furnace to below 120°C and then air-cooling it to room temperature.

2. The method for preparing high-strength, toughness, and wear-resistant alloy steel according to claim 1, characterized in that, The chemical composition and mass fraction of the titanium iron powder are: 68.33-71.47% Ti, <0.5% Al, <0.10% Si, <0.20% Mn, <0.20% C, <0.03% P, <0.03% S, <0.50% V, with the balance being Fe and unavoidable impurities.

3. The method for preparing high-strength, toughness, and wear-resistant alloy steel according to claim 1, characterized in that, The chemical composition and mass fraction of the lanthanum-cerium rare earth ferrosilicon powder are: 36.22-37.68% La+Ce, 43.88-46.02% Si, <2.0% Ba, <2.0% Ca, <1.5% Al, <0.3% Ti, <0.5% Mn, with the balance being Fe and unavoidable impurities.

4. The high-strength, high-toughness, and wear-resistant alloy steel prepared by the method according to any one of claims 1-3.

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