A high hardening wear-resistant steel ball and preparation method thereof

Abstract

The invention discloses a high-hardening wear-resistant steel ball and a preparation method thereof, belonging to the field of steel balls. Firstly, scrap steel, high nitrogen ferrochrome FeCrN10 and a carburizer are mixed and heated to melt, and after the molten steel is melted, ferrosilicon, ferromanganese nitride and aluminum are added in sequence, and the molten steel in the furnace is controlled to be: 0.92-1.06% C, 1.69-1.86% Mn, 0.72-0.91% Si, 0.85-0.98% Cr, 0.18-0.25% N, 0.68-0.77% Al, ≤0.040% P, ≤0.035% S, and the remainder is Fe and inevitable impurities, and then the molten steel is taken out of the furnace into a ladle, a rare earth-magnesium-silicon-barium-calcium multi-element alloy is placed in advance at the bottom of the ladle, and boron-titanium alloy molten steel is also added to the ladle, and the mixed molten steel is cast into a cylindrical billet, and after the cylindrical billet is rolled, forged and quenched, a steel ball with high hardenability and excellent wear resistance is obtained, and the popularization and use of the steel ball has good economic and social benefits.

Description

Technical Field

[0001] The invention discloses a wear-resistant steel ball and a preparation method thereof, in particular to a high-hardening wear-resistant steel ball and a preparation method thereof, belonging to the technical field of preparation of steel balls for mills. Background Art

[0002] Grinding is one of the key processes in mineral processing. With the increase in the global processing volume of low-grade ores and the large-scale and automated production equipment, the efficiency of mineral processing is required to be continuously improved. So far, the grinding process has been continuously shifting towards a more efficient process, and its obvious trend is to use large-scale semi-autogenous grinding mills. At present, many mines directly use large-sized steel balls in large semi-autogenous grinding mills to drop them from a height of several meters to hit the ore to achieve the purpose of crushing the ore. Therefore, the hardness and impact performance of the steel balls are very important for the crushing process. In order to improve the grinding efficiency, large-sized steel balls are required to have excellent hardenability to ensure that the hardness difference between the surface and the core of the steel balls is small. In order to improve the hardenability of steel balls, Chinese invention patent CN117604393A discloses a continuous casting billet for low-temperature resistant, high hardenability and low wear steel balls and a production method thereof. The continuous casting billet includes the following chemical components in mass percentage: C: 0.55% to 0.65%, Si: 1.30% to 1.70%, Mn: 0.70% to 0.90%, P: ≤0.025%, S: ≤0.005%, Al: 0.010% to 0.060%, Cr: 0.80% to 1.00%, Mo: 0.05% to 0.25%, Ni: 0.05% to 0.25%, B: 0.0010% to 0.0030%, and the balance is Fe and unavoidable impurities. The invented production method of continuous casting billets for low-temperature resistant, high hardenability and low-wear steel balls can ensure that the material gas, inclusions, mechanical properties, etc. meet the requirements of wear resistance and low consumption of steel balls in extremely low-temperature environments, can ensure the quality of low-temperature resistant, high hardenability and low-wear steel balls, improve production efficiency, reduce wear, save energy, reduce carbon dioxide emissions, protect the environment, and save users' production costs. Chinese invention patent CN116875914A also discloses a high-strength and toughness steel ball and a production method thereof. The steel ball contains, by weight percentage, 0.13%-0.15% C, 5.50%-6.70% W, 1.50%-2.50% Mn, 0.25%-0.55% Co, 0.22%-0.45% Mo, and the remainder is Fe and inevitable impurities. A production method for a high-strength and toughness steel ball comprises the following steps: A. smelting iron ore, reducing the ore to molten iron, and desulfurizing; B. introducing high-pressure oxygen into a converter to heat the molten iron, adding lime for dephosphorization, and removing impurities. The invention carries out desulfurization and dephosphorization to improve the toughness of the steel ball. By adding C, W, Mn, Co and Mo into molten iron, C increases the rigidity of the steel ball and has a low content to avoid the steel ball being too brittle. Mn can improve the strength of the steel, weaken and eliminate the adverse effects of sulfur, and improve the hardenability of the steel. W can improve the red hardness and heat strength of the steel and improve the wear resistance of the steel. Co further improves the strength of the steel ball.Chinese invention patent CN107739986A also discloses a large-diameter forged wear-resistant steel ball specially used for mines and a preparation method thereof, which relates to the technical field of wear-resistant materials. Its chemical composition by weight percentage includes: C0.8-1.2%, Si0.6-0.9%, Mn1.2-1.5%, Cr1.0-1.5%, Mo0.1-0.3%, V0.05-0.15%, Ti0.1-0.2%, Al0.05-0.15%, Cu0.05-0.15%, Zr0.05-0.15%, Hf0.05-0.15%, B0.08-0.2%, P≤0.02%, S≤0.01%, and the rest is Fe and inevitable impurities; its preparation method includes smelting, forging and heat treatment. The invention rationally optimizes the chemical element composition and content in forged wear-resistant steel balls. The added hardenability elements such as Mn, Mo, Cr, V, Ti, Cu, etc. can increase the stability of supercooled austenite and improve the hardenability of steel, reduce the difference in hardness between the core and surface of large-diameter grinding balls, and the prepared grinding balls have smooth and defect-free surfaces, high hardness, good toughness, and are not easy to break. Their performance is comparable to that of high-chromium grinding balls, and they can replace cast balls for wet grinding of ore to improve grinding efficiency. Chinese invention patent CNCN107574389A also discloses a chromium-nickel-molybdenum steel ball and a preparation method thereof, wherein the chromium-nickel-molybdenum steel ball of the invention comprises the following components in percentage by mass: carbon C 0.6-1.5%, silicon Si 0.1-0.3%, samarium Sm 0.4-0.5%, titanium Ti 0.8-1.0%, nickel Ni 0.1-0.3%, europium Eu 0.04-0.06%, vanadium V 0.2-0.4%, cerium Ce 0.05-0.1%, cobalt Co 0.15-0.25%, holmium Ho 0-0.02%, praseodymium Pr 0.5-0.8%, chromium Cr 20-25%, and the balance is iron Fe. The preparation method of the invention is simple, the cast steel has good hardenability, and the steel has good strength, toughness and wear resistance. Chinese invention patent CNCN104250702A also discloses a wear-resistant steel ball and its preparation method. The components of the steel ball are calculated by weight percentage: the weight percentage of C is 0.5-0.8%; the weight percentage of Si is 0.25-0.7%; the weight percentage of Mn is 0.65-1.65%; the weight percentage of Mo is 0.1-0.2%; the weight percentage of S and P is ≤0.04%. The preparation method of the steel ball adopts quartz sand and river sand molding, and the smelting adopts acid lining, double slag method, charging the bottom of the crucible, the slag accounts for 1%-1.5% of the charging, adding scrap steel, melting, adjusting the composition, slagging for final deoxidation, and tapping at 1550-1600℃; the heat treatment first performs quenching treatment, and then performs tempering treatment after quenching. The steel ball produced by the invention has high hardenability, can increase the service life of the steel ball, has high wear resistance, reduces costs, and reduces the ball breakage rate.Chinese invention patent CNCN1186871A also discloses a wear-resistant alloy steel and a wear-resistant steel ball made of the steel. The alloy steel is composed of the following components by weight: C0.18-0.45%, Si0.1-1.8%, Mn0.4-2.0%, B0.0005-0.005%, Cr0.2-1.0%, and the balance is iron. The alloy steel of the invention has good hardenability and high toughness, overcoming the disadvantage of the existing low-carbon alloy steel that cannot be water-quenched. The steel ball made of the alloy steel has good wear resistance and a crushing rate of ≤2%. Chinese invention patent CNCN107574380A also discloses a high-hardness fine-grained large-size forged grinding ball steel, which includes the following chemical components and mass percentages: C: 0.70-0.85%, Mn: 1.0-1.3%, Cr: 0.8-0.95%, Si: 0.6-0.8%, Mo: 0.08-0.3%, Nb: 0.02-0.06%, Al: 0.01-0.06%, Cu: ≤0.01%, S: ≤0.025%, P: ≤0.025%, and the rest is iron. The forged grinding ball steel of the invention adopts the electric furnace steelmaking or converter steelmaking + LF refining + continuous casting full protection casting to produce round billets + hot rolling process to produce round steel, which has been generally built by steelmaking enterprises in my country. The steel for forging grinding balls of the invention has high hardenability, the original austenite grain size is still small under high temperature and long-term heating conditions, and the surface is not easy to decarburize. Chinese invention patent CNCN1116250A also discloses a high hardenability hot-rolled steel ball and its heat treatment method, the components of which are (weight %): C0.40-0.85, Si1.51-2.0, Mn1.81-2.9, Cr0.20-0.79, Cu0.001-0.70, Mo0.001-0.15, Ce0.0005-0.05, S≤0.05, P≤0.04, and the rest is Fe. Its manufacturing method is to carry out hot rolling or die forging after smelting and casting, and then heat treatment. The steel ball of the invention has low cost, strong resistance to temper softening, high hardenability, high hardness and small difference between surface and core hardness, good wear resistance, easy rolling (forging) and heat treatment, and energy saving. It is suitable for grinding various materials in mining, building materials, electric power and other industries. Chinese invention patent CNCN110106431A also discloses a formula of energy-saving steel balls, including steel, carbon, silicon, manganese, chromium, tungsten oxide and molybdenum oxide, the carbon content is 2.0-3.0%, the silicon content is 0.5-1.0%, the manganese content is 0.8-2.0%, the chromium content is 1.5-2.0%, the tungsten oxide content is 2-4%, the molybdenum oxide content is 0.4-0.8%, and the remainder is steel. The formula of the energy-saving steel ball and its preparation process can improve the hard layer depth and hardenability of the steel ball as a whole by adding carbon, silicon, manganese, chromium, molybdenum oxide and manganese oxide, thereby improving the overall hardness of the steel ball, thereby increasing the service life of the steel ball, reducing the consumption of the steel ball, and achieving the effect of energy saving and consumption reduction.The above steel balls have the disadvantages of low hardness and poor wear resistance, or a large amount of precious alloy elements such as tungsten, molybdenum, nickel, vanadium, cobalt, etc. are added, resulting in high production costs and poor market competitiveness.

[0003] In order to further improve the performance of steel balls, Chinese invention patent CNCN110527888A discloses a method for producing high hardenability steel balls, including the following specific steps: prepare C, Mn, Ni, Si and Cr raw materials according to the ratio; put the prepared raw materials into a smelting furnace for heating and melting, and after smelting, add acetic acid and formaldehyde to the molten metal; quickly inject the molten metal into a metal casting mold to cast a semi-finished steel ball; the semi-finished steel ball is heat-treated after grinding and cleaning, and the steel ball is obtained after cooling to room temperature. The steel balls produced by this invention have high strength, permeability and wear resistance. However, the addition of acetic acid and formaldehyde to high-temperature molten metal is prone to explosion accidents, which seriously affects production safety. Chinese invention patent CNCN110923425A also discloses a water space intermittent quenching equipment and method for quenching wear-resistant steel balls in mines. The water space intermittent quenching equipment includes an external water pool, a peripheral water pipe system, a quenching tank, a quenching frame structure, a gate mechanism, an upper water channel and a lower water channel; the quenching frame structure is arranged directly above the quenching tank, and includes rollers, a lifting frame, a guide column, a top plate, an upper hydraulic cylinder, a lower hydraulic cylinder, a supporting device, and a quenching workpiece frame. The water space intermittent quenching equipment can realize the alternating quenching treatment of the steel ball by water and air, and can effectively ensure that the cooling rate of the steel ball is greater than the critical cooling rate, obtain more martensitic structure, and maintain the toughness of its core, and can significantly improve the hardenability, hardness, wear resistance and impact toughness of the steel ball, so as to ensure the continuous construction work, improve the work efficiency, and reduce the production cost. Chinese invention patent CN115852131A also discloses a method for producing a high hardenability steel ball, which includes the following steps: S1, forging steel balls: the raw material of the steel balls is cylindrical steel material; it is placed in a heating furnace and heated to 1050-1200°C, kept warm for 20 minutes, placed in a forging machine to forge into steel balls, and then quenched with oil; S2, when the surface temperature of the steel balls drops to 60-80°C, the temperature is raised to 800-900°C, kept warm for 50-60 minutes, quenched with water at a temperature of 30-40°C for 5-8s, the steel balls are tempered, and then the tempering temperature is controlled between 200-260°C for 1-2h; S3, air cooling: the steel balls are air cooled to the design temperature, and the steel balls are pre-cooled, so that the cooling rate curves of different areas of the steel balls are relatively gentle and the hardening depth is greater.Chinese utility model patent CN218435875U also discloses a high hardenability heat treatment device for forged steel balls, including a water quenching pool and a tempering pool, a tempering pool is arranged on one side of the water quenching pool, and a material shunting rack is arranged between the water quenching pool and the tempering pool through a leg frame, and a material shunting trough is provided on the top surface of the material shunting rack, a first conveying trough and a second conveying trough are respectively fixedly installed obliquely inside the water quenching pool and the tempering pool, and the first conveying trough and the second conveying trough are of the same structure, and an auger is arranged inside the first conveying trough, one end of the auger is rotatably connected to the inner wall of one end of the first conveying trough through a rotating connector, and a discharge port is provided on the bottom surface of one end of the first conveying trough, and the other end of the auger penetrates the water quenching pool and is rotatably connected to the water quenching pool through a sealed bearing. Beneficial effects: The device improves the convenience of water quenching and tempering of forged steel balls, improves the heat treatment efficiency of forged steel balls, and thus improves production efficiency, and has a wide range of applications, is easy to adjust, and is suitable for large-scale promotion and use. Chinese utility model patent CN212102933U also discloses a water space intermittent quenching equipment for quenching wear-resistant steel balls in mines. The water space intermittent quenching equipment includes an external water pool, a peripheral water pipe system, a quenching tank, a quenching frame structure, a gate mechanism, an upper water channel and a lower water channel; the quenching frame structure is arranged directly above the quenching tank, and includes rollers, a lifting frame, a guide column, a top plate, an upper hydraulic cylinder, a lower hydraulic cylinder, a supporting device, and a quenching workpiece frame. The water space intermittent quenching equipment can realize alternating quenching treatment of steel balls by water and air, and can effectively ensure that the cooling rate of the steel balls is greater than the critical cooling rate, obtain more martensitic structure, and maintain the toughness of its core, which can significantly improve the hardenability, hardness, wear resistance and impact toughness of the steel balls. The production process of steel balls using the above method is complicated, and the performance stability of the steel balls is poor. Summary of the invention

[0004] In view of the low hardness, poor hardenability and wear resistance of commonly used wear-resistant steel balls, in order to improve the hardenability of steel balls, it is necessary to add more precious alloy elements such as tungsten, molybdenum, nickel, vanadium, cobalt, etc., resulting in high production costs and poor market competitiveness of steel balls, or the use of complex equipment and processes to manufacture steel balls, resulting in poor performance stability of steel balls. The present invention adds a small amount of titanium, nitrogen, aluminum, boron, magnesium and rare earth elements to the manganese-silicon alloyed steel balls to achieve a significant improvement in the hardness, hardenability and wear resistance of the steel balls.

[0005] A high hardenability wear-resistant steel ball and a preparation method thereof, the specific preparation process steps are:

[0006] ① Use electric furnace to melt wear-resistant steel. First, mix scrap steel, high nitrogen ferrochrome FeCrN10 and carburizer and heat to melt. After the molten steel is melted, add ferrosilicon and ferromanganese nitride in turn. After the temperature is quickly raised to 1649-1665℃, add metal aluminum, and control the chemical composition and mass fraction of the molten steel in the furnace to: 0.92-1.06% C, 1.69-1.86% Mn, 0.72-0.91% Si, 0.85-0.98% Cr, 0.18-0.25% N, 0.68-0.77% Al, ≤0.040% P, ≤0.035% S, the balance is Fe and inevitable impurity elements; after keeping warm for 8-12 minutes, the high-temperature molten steel is taken out of the furnace into a ladle, and a rare earth-magnesium-silicon-barium-calcium multi-element alloy preheated at 730-780°C for 120-150 minutes is placed at the bottom of the ladle in advance, the particle size of the rare earth-magnesium-silicon-barium-calcium multi-element alloy is 3-7mm, and the amount of the rare earth-magnesium-silicon-barium-calcium multi-element alloy added accounts for 1.2-1.4% of the mass fraction of the high-temperature molten steel entering the ladle;

[0007] ② Using a medium frequency induction furnace to melt boron-titanium alloy molten steel; first heat and melt Q235 scrap steel, then raise the temperature to 1603-1622°C, and sequentially add ferrotitanium and ferroboron preheated at 900-980°C for 2-3 hours, and control the chemical composition and mass fraction of the boron-titanium alloy molten steel obtained in the furnace to 8.35-8.82% Ti, 7.21-7.75% B, and the balance is Fe and inevitable residual elements; continue to raise the temperature to 1624-1637°C, and take the boron-titanium alloy molten steel in the medium frequency induction furnace out of the furnace into the ladle containing high-temperature molten steel and rare earth-magnesium-silicon-barium-calcium multi-element alloy in step ①; the amount of boron-titanium alloy molten steel added accounts for 9.2-9.5% of the mass fraction of the high-temperature molten steel entering the ladle;

[0008] ③ After the molten steel in step ② is deslagging and standing, when the temperature drops to 1503-1519°C, the molten steel is poured into a crystallizer on a continuous casting machine to be continuously cast into a cylindrical billet with a diameter of Φ520-550mm, and the cylindrical billet is directly rolled into a cylindrical steel with a diameter of Φ110-130mm on a rolling mill;

[0009] ④ The cylindrical steel with a diameter of Φ110-130mm obtained in step ③ is heated to 1120-1180℃ by a walking natural gas heating furnace, kept warm for 160-200 minutes, and then sheared into a cylinder with a length of 215-240mm required for a single ball by a rod shearing machine, and the cylinder is rough forged by a CNC hammer, and the deformation amount is controlled at 11-12% each time. After 4-6 deformations, a blank steel ball is obtained; then the blank steel ball is finely forged by an air hammer to obtain a Φ160mm-180mm steel ball;

[0010] ⑤ Step ④ After fine forging, the surface temperature of the steel ball drops to 875-897°C, and it enters a water pool for quenching. The temperature of the water in the water pool is 58-67°C, and the mass ratio of water to the steel ball in the water pool is greater than 15:1; after the steel ball is cooled in the water pool for 220-240 seconds, the steel ball is taken out; and the quenched steel ball is tempered at 180-200°C for 16-18 hours, furnace cooled to a temperature below 150°C, and air cooled to room temperature after being taken out of the furnace, a highly hardenable and wear-resistant steel ball can be obtained.

[0011] As mentioned above, the chemical composition and mass fraction of the rare earth-magnesium-silicon-barium-calcium multi-element alloy are: 8.26-8.71% RE, 4.84-5.27% Mg, 28.60-29.75% Si, 4.38-4.66% Ba, 5.08-5.79% Ca, and the remainder is Fe and unavoidable impurity elements; the rare earth elements include any one or two of lanthanum (La) and cerium (Ce).

[0012] In view of the shortcomings of commonly used wear-resistant steel balls such as low hardness, poor hardenability and wear resistance, the present invention proposes adding a small amount of titanium, nitrogen, aluminum, boron, magnesium and lanthanum-cerium rare earth elements to manganese-silicon alloyed steel balls to significantly improve the hardness, hardenability and wear resistance of the steel balls. A high-hardenability wear-resistant steel ball and a preparation method thereof. The specific preparation process steps are: firstly, an electric furnace is used to smelt wear-resistant steel, scrap steel, high nitrogen ferrochrome FeCrN10 and a carburizer are mixed and heated to melt, ferrosilicon and ferromanganese nitride are added in sequence after the molten steel is melted, and metal aluminum is added after the temperature is quickly raised to 1649-1665°C, and the chemical composition and mass fraction of the molten steel in the furnace are controlled to be: 0.92-1.06% C, 1.69-1.86% Mn, 0.72-0.91% Si, 0.85-0.98% Cr, 0.18-0.25% N, 0.68-0.77% Al, ≤0.040% P, ≤0.035% S, and the remainder is Fe and unavoidable impurity elements. The wear-resistant steel ball of the present invention contains 1.69-1.86% Mn. Manganese is an element that significantly expands the λ phase region. Manganese can reduce the martensitic transformation temperature of steel and the speed of phase transformation in steel, thereby significantly improving the hardenability of steel. However, if the manganese content is too high, the residual austenite content will be significantly increased, which will reduce the hardness and wear resistance of the steel ball. The manganese content in the steel ball is controlled to 1.69-1.86% Mn. In the present invention, 0.72-0.91% Si is added. In addition to having a deoxidizing effect, silicon is solid-dissolved in the iron matrix, which has a good solid solution strengthening effect on iron.

[0013] The wear-resistant steel of the present invention contains 0.18-0.25% N and 0.68-0.77% Al. Nitrogen and aluminum react easily at high temperature to generate AlN wear-resistant hard phase with a melting point of up to 2800-3000°C and a hardness of up to 2300-3300 HV, which is evenly distributed in the steel matrix and can significantly improve the wear resistance of the steel ball. The nitrogen element dissolved in the steel can also significantly improve the hardenability of the wear-resistant steel ball. The present invention also adds 0.85-0.98% Cr. On the one hand, the addition of chromium element can improve the hardenability of the steel ball. On the other hand, chromium element can be combined with the subsequently added boron element to generate a high-hardness M (M = Cr, Fe) 2B phase, which significantly improves the wear resistance of the steel ball.

[0014] After the molten steel is kept warm for 8-12 minutes, the high-temperature molten steel is taken out of the furnace into the ladle. The rare earth-magnesium-silicon-barium-calcium multi-element alloy preheated at 730-780℃ for 120-150 minutes is placed at the bottom of the ladle. The rare earth elements include any one or two of lanthanum (La) and cerium (Ce). Its chemical composition and mass fraction are: 8.26-8.71% RE, 4.84-5.27% Mg, 28.60-29.75% Si, 4.38-4.66% Ba, 5.08-5.79% Ca, and the balance is Fe and unavoidable impurity elements. The particle size of the rare earth-magnesium-silicon-barium-calcium multi-element alloy is 3-7mm, and the amount of rare earth-magnesium-silicon-barium-calcium multi-element alloy added accounts for 1.2-1.4% of the mass fraction of the high-temperature molten steel entering the ladle. Steel smelted with only the above-mentioned ingredients still has low hardness, poor wear resistance and hardenability that need to be further improved. The present invention also uses a medium-frequency induction furnace to melt boron-titanium alloy molten steel; first heat and melt Q235 scrap steel, then heat it to 1603-1622°C, and add ferrotitanium and ferroboron preheated at 900-980°C for 2-3 hours in sequence, and control the chemical composition and mass fraction of the boron-titanium alloy molten steel in the furnace to 8.35-8.82% Ti, 7.21-7.75% B, and the remainder is Fe and inevitable residual elements; continue to heat it to 1624-1637°C, and take the boron-titanium alloy molten steel in the medium-frequency induction furnace out of the furnace into a ladle containing high-temperature molten steel and rare earth-magnesium-silicon-barium-calcium multi-element alloy; the amount of boron-titanium alloy molten steel added accounts for 9.2-9.5% of the mass fraction of the high-temperature molten steel entering the ladle. The boron and titanium in the boron-titanium alloy steel are easily combined to form TiB2 particles with a melting point of 3060°C and a hardness of 2800-3500HV. The TiB2 particles are evenly distributed on the steel matrix, which can significantly improve the hardness and wear resistance of the steel ball. In addition, part of the boron element is dissolved in the steel matrix, which can significantly improve the hardenability of the steel.

[0015] The density of TiB2 is only 4.52g / cm 3, significantly lower than the density of molten steel. In order to ensure that the TiB2 particles are evenly distributed in the molten steel, the present invention pre-adds a rare earth-magnesium-silicon-barium-calcium multi-element alloy accounting for 1.2-1.4% of the mass fraction of the high-temperature molten steel entering the ladle at the bottom of the ladle. The rare earth-magnesium-silicon-barium-calcium multi-element alloy contains 4.84-5.27% Mg. The melting point of magnesium is 648.8°C and the boiling point is 1107°C. It is an active metal and is very easy to gasify under the action of high-temperature molten steel, causing the molten steel in the ladle to churn and promote the uniform distribution of TiB2 particles in the molten steel. In addition, after adding more silicon and manganese elements to the steel, the cast steel structure is significantly coarse, which will significantly reduce the plasticity and toughness of the steel ball. In order to overcome the adverse effects brought by the addition of silicon and manganese elements, part of the titanium element in the steel of the present invention is combined with carbon to generate fine TiC solidification particles with high melting points. The fine TiC solidification particles with high melting points can be used as the primary austenite solidification crystallization core, which has a significant effect of refining the wear-resistant cast steel solidification structure. The present invention pre-adds rare earth-magnesium-silicon-barium-calcium multi-element alloy to the bottom of the ladle, which contains 8.26-8.71% RE, 4.38-4.66% Ba, 5.08-5.79% Ca in addition to 4.84-5.27% Mg. The rare earth elements include any one or two of lanthanum (La) and cerium (Ce). The addition of these micro-alloy elements has the effect of significantly purifying molten steel and improving the morphology and distribution of inclusions, and has the effect of significantly improving the strength and toughness of wear-resistant steel.

[0016] After the molten steel in the ladle of the present invention is deslagging and standing, when the temperature drops to 1503-1519°C, the molten steel is poured into a crystallizer on a continuous casting machine, and continuously cast into a cylindrical billet with a diameter of Φ520-550mm, and the cylindrical billet is directly rolled into a cylindrical steel with a diameter of Φ110-130mm on a rolling mill. Directly rolling the cylindrical billet with a diameter of Φ520-550mm on a rolling mill into a cylindrical steel with a diameter of Φ110-130mm can make the steel structure finer and denser, and also promote the high-hardness M (M = Cr, Fe) 2B phase from large block and mesh distribution to isolated fine ball distribution, significantly improving the toughness and impact fatigue resistance of the wear-resistant steel ball processed subsequently. The invention also heats the obtained cylindrical steel with a diameter of Φ110-130 mm to 1120-1180° C. by a stepping natural gas heating furnace, keeps the temperature for 160-200 minutes, and then cuts it into a cylinder with a length of 215-240 mm required for a single ball by a rod shearing machine, and roughly forges the cylinder by a numerical control hammer, controls the deformation amount at 11-12% each time, and obtains a blank steel ball after 4-6 deformations. The blank steel ball contains more elements such as manganese, nitrogen, boron, chromium and silicon that improve hardenability and has excellent hardenability. Then, the blank steel ball is finely forged by an air hammer to obtain a Φ160mm-180mm steel ball.

[0017] In the present invention, when the surface temperature of the steel ball after fine forging drops to 875-897°C, it enters the water pool for quenching, mainly to obtain a high-hardness martensitic matrix and improve the wear resistance of the steel ball. However, the steel ball of the present invention contains more carbon and boron elements, which are prone to cracking during the quenching process, and the water temperature and cooling time in the quenching water pool need to be strictly controlled. The temperature of the water in the water pool is 58-67°C, and the mass ratio of water to steel balls in the water pool is greater than 15:1; after the steel balls are cooled in the water pool for 220-240 seconds, the steel balls are taken out. In order to eliminate the residual stress inside the steel balls and prevent the steel balls from peeling and breaking during use, the quenched steel balls need to be tempered at 180-200°C for 16-18 hours, furnace cooled to a temperature below 150°C, and air cooled to room temperature after being taken out of the furnace, so as to obtain highly hardenable and wear-resistant steel balls.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The wear-resistant steel ball of the present invention uses cheap Si and Mn as main alloying elements and does not contain expensive alloying elements such as molybdenum, nickel, tungsten, vanadium, and niobium, so the cost is low.

[0020] (2) The wear-resistant steel ball of the present invention contains a large amount of elements such as manganese, nitrogen and boron that significantly improve the hardenability. The hardenability of the steel ball is significantly improved through the interaction of the elements, and the large-diameter steel ball of Φ160mm-180mm can be fully hardened, reducing the hardness difference between the surface and the center of the steel ball, thereby improving the wear resistance of the steel ball during use.

[0021] (3) The wear-resistant steel ball of the present invention contains a large amount of high-hardness M (M = Cr, Fe) 2B phase, TiB 2 and AlN, which significantly improves the wear resistance of the steel ball. Compared with commonly used wear-resistant steel balls, the wear resistance is improved by more than 40%, and the production cost is similar. The promotion and application of the steel ball of the present invention has good economic and social benefits.

[0022] (4) The wear-resistant steel ball of the present invention has excellent comprehensive mechanical properties. The surface hardness of the large diameter steel ball of Φ160mm-180mm exceeds 65HRC, the core hardness exceeds 62HRC, and the impact toughness is greater than 35J / cm 2 .

[0023] (5) The wear-resistant steel ball of the present invention realizes residual heat treatment after forging, has a wide process adjustable range, is easy to control quality, and is cooled by water quenching, which is energy-saving and environmentally friendly. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the examples, but the present invention is not limited to the following examples.

[0025] Embodiment 1:

[0026] A high-hardening wear-resistant steel ball and a preparation method thereof, wherein two electric furnaces are used to melt high-temperature molten steel of wear-resistant steel and molten steel of boron-titanium alloy, and the specific preparation process steps are:

[0027] ① Use electric furnace to melt wear-resistant steel. First, mix scrap steel, high nitrogen ferrochrome FeCrN10 and carburizer and heat to melt. After the molten steel is clear, add ferrosilicon and ferromanganese nitride in turn. After rapidly heating to 1658℃, add metal aluminum. The chemical composition and mass fraction of the molten steel in the furnace are controlled at: 0.99% C, 1.81% Mn, 0.88% Si, 0.90% Cr, 0.23% N, 0.71% Al, 0.039% P, 0.030% S, and the balance is Fe and unavoidable impurity elements; after keeping warm for 10 minutes, the high-temperature molten steel is taken out of the furnace to the steel ladle, a rare earth-magnesium-silicon-barium-calcium multi-element alloy preheated at 750° C. for 140 minutes is placed in advance at the bottom of the ladle (the chemical composition and mass fraction of the rare earth-magnesium-silicon-barium-calcium multi-element alloy are: 8.54% Ce, 4.90% Mg, 28.93% Si, 4.52% Ba, 5.69% Ca, and the balance is Fe and unavoidable impurity elements), the particle size of the rare earth-magnesium-silicon-barium-calcium multi-element alloy is 3-7 mm, and the amount of the rare earth-magnesium-silicon-barium-calcium multi-element alloy added accounts for 1.3% of the mass fraction of the high-temperature molten steel entering the ladle;

[0028] ② Use a 1000 kg medium frequency induction furnace to melt boron-titanium alloy molten steel; first heat and melt Q235 scrap steel, then raise the temperature to 1617°C, and add ferrotitanium and ferroboron preheated at 950°C for 2.5 hours in sequence, and control the chemical composition and mass fraction of the boron-titanium alloy molten steel in the furnace to 8.64% Ti, 7.58% B, and the balance is Fe and unavoidable residual elements; continue to raise the temperature to 1633°C, and take the boron-titanium alloy molten steel in the medium frequency induction furnace out of the furnace into the ladle containing high-temperature molten steel and rare earth-magnesium-silicon-barium-calcium multi-element alloy in step ①; the amount of boron-titanium alloy molten steel added accounts for 9.4% of the mass fraction of the high-temperature molten steel entering the ladle;

[0029] ③ After the molten steel in step ② is slag-stripped and allowed to stand, when the temperature drops to 1512°C, the molten steel is poured into a crystallizer on a continuous casting machine to be continuously cast into a cylindrical billet with a diameter of Φ530mm, and the cylindrical billet is directly rolled into a cylindrical steel with a diameter of Φ120mm on a rolling mill;

[0030] ④ The cylindrical steel with a diameter of Φ120 mm obtained in step ③ is heated to 1150°C by a walking natural gas heating furnace, kept warm for 180 minutes, and then sheared into a cylinder with a length of 227.5 mm required for a single ball by a rod shearing machine, and the cylinder is rough-forged by a CNC hammer, and the deformation amount is controlled at 10% each time. After 5 deformations, a blank steel ball is obtained; then the blank steel ball is finely forged by an air hammer to obtain a Φ170 mm steel ball;

[0031] ⑤ Step ④ After fine forging, the surface temperature of the steel ball drops to 878-894°C, and it enters a water pool for quenching. The temperature of the water in the water pool is 61°C, and the mass ratio of water to the steel ball in the water pool is greater than 15:1; after the steel ball is cooled in the water pool for 230 seconds, the steel ball is taken out; and the quenched steel ball is tempered at 190°C for 17 hours, furnace cooled to a temperature below 150°C, and air cooled to room temperature after being taken out of the furnace, a highly hardenable and wear-resistant steel ball can be obtained, and its mechanical properties are shown in Table 1.

[0032] Embodiment 2:

[0033] A high-hardening wear-resistant steel ball and a preparation method thereof, wherein two electric furnaces are used to melt high-temperature molten steel of wear-resistant steel and molten steel of boron-titanium alloy, and the specific preparation process steps are:

[0034] ① Use electric furnace to melt wear-resistant steel. First, mix scrap steel, high nitrogen ferrochrome FeCrN10 and carburizer and heat to melt. After the molten steel is melted, add ferrosilicon and ferromanganese nitride in turn. After the temperature is quickly raised to 1649℃, add metal aluminum. The chemical composition and mass fraction of the molten steel in the furnace are controlled at: 0.92% C, 1.86% Mn, 0.72% Si, 0.98% Cr, 0.18% N, 0.68% Al, 0.037% P, 0.028% S, and the remainder is Fe and unavoidable impurity elements; after keeping warm for 12 minutes, the high-temperature molten steel is taken out of the furnace to the steel A ladle, wherein a rare earth-magnesium-silicon-barium-calcium multi-element alloy preheated at 730° C. for 150 minutes is placed in advance at the bottom of the ladle (the chemical composition and mass fraction of the rare earth-magnesium-silicon-barium-calcium multi-element alloy are: 8.26% La, 5.27% Mg, 28.60% Si, 4.66% Ba, 5.08% Ca, and the balance is Fe and unavoidable impurity elements), the particle size of the rare earth-magnesium-silicon-barium-calcium multi-element alloy is 3-7 mm, and the amount of the rare earth-magnesium-silicon-barium-calcium multi-element alloy added accounts for 1.2% of the mass fraction of the high-temperature molten steel entering the ladle;

[0035] ② Use a 2000 kg medium frequency induction furnace to melt boron-titanium alloy molten steel; first heat and melt Q235 scrap steel, then raise the temperature to 1603°C, and add ferrotitanium and ferroboron preheated at 900°C for 3 hours in sequence, and control the chemical composition and mass fraction of the boron-titanium alloy molten steel in the furnace to 8.35% Ti, 7.75% B, and the balance is Fe and unavoidable residual elements; continue to raise the temperature to 1637°C, and take the boron-titanium alloy molten steel in the medium frequency induction furnace out of the furnace into the ladle containing high-temperature molten steel and rare earth-magnesium-silicon-barium-calcium multi-element alloy in step ①; the amount of boron-titanium alloy molten steel added accounts for 9.5% of the mass fraction of the high-temperature molten steel entering the ladle;

[0036] ③ After the molten steel in step ② is deslagging and standing, when the temperature drops to 1503°C, the molten steel is poured into a crystallizer on a continuous casting machine to be continuously cast into a cylindrical billet with a diameter of Φ520mm, and the cylindrical billet is directly rolled into a cylindrical steel with a diameter of Φ110mm on a rolling mill;

[0037] ④ The cylindrical steel with a diameter of Φ110 mm obtained in step ③ is heated to 1120°C by a stepping natural gas heating furnace, kept warm for 200 minutes, and then sheared into a cylinder with a length of 225.7 mm required for a single ball by a rod shearing machine, and the cylinder is rough-forged by a CNC hammer, and the deformation amount is controlled at 11% each time. After 6 deformations, a blank steel ball is obtained; then the blank steel ball is finely forged by an air hammer to obtain a Φ160 mm steel ball;

[0038] ⑤ Step ④ After fine forging, the surface temperature of the steel ball drops to 875-891°C, and it enters a water pool for quenching. The temperature of the water in the water pool is 58°C, and the mass ratio of water to the steel ball in the water pool is greater than 15:1; after the steel ball is cooled in the water pool for 220 seconds, the steel ball is taken out; and the quenched steel ball is tempered at 180°C for 18 hours, furnace cooled to a temperature below 150°C, and air cooled to room temperature after being taken out of the furnace, a highly hardenable and wear-resistant steel ball can be obtained, and its mechanical properties are shown in Table 1.

[0039] Embodiment 3:

[0040] A high-hardening wear-resistant steel ball and a preparation method thereof, wherein two electric furnaces are used to melt high-temperature molten steel of wear-resistant steel and molten steel of boron-titanium alloy, and the specific preparation process steps are:

[0041] ① Use electric furnace to melt wear-resistant steel. First, mix scrap steel, high nitrogen ferrochrome FeCrN10 and carburizer and heat to melt. After the molten steel is melted, add ferrosilicon and ferromanganese nitride in turn. After the temperature is quickly raised to 1665℃, add metal aluminum, and control the chemical composition and mass fraction of the molten steel in the furnace to: 1.06% C, 1.69% Mn, 0.91% Si, 0.85% Cr, 0.25% N, 0.77% Al, 0.032% P, 0.034% S, and the remainder is Fe and unavoidable impurity elements; after keeping warm for 8 minutes, take the high-temperature molten steel out of the furnace and put it into the ladle. A rare earth-magnesium-silicon-barium-calcium multi-element alloy preheated at 780° C. for 120 minutes is placed at the bottom of the ladle in advance (the chemical composition and mass fraction of the rare earth-magnesium-silicon-barium-calcium multi-element alloy are: 8.71% (La+Ce), 4.84% Mg, 29.75% Si, 4.38% Ba, 5.79% Ca, and the balance is Fe and unavoidable impurity elements), the particle size of the rare earth-magnesium-silicon-barium-calcium multi-element alloy is 3-7 mm, and the amount of the rare earth-magnesium-silicon-barium-calcium multi-element alloy added accounts for 1.4% of the mass fraction of the high-temperature molten steel entering the ladle;

[0042] ② Use a 1500 kg medium frequency induction furnace to melt boron-titanium alloy molten steel; first heat and melt Q235 scrap steel, then raise the temperature to 1622°C, and add ferrotitanium and ferroboron preheated at 980°C for 2 hours in sequence, and control the chemical composition and mass fraction of the boron-titanium alloy molten steel in the furnace to 8.82% Ti, 7.21% B, and the balance is Fe and unavoidable residual elements; continue to raise the temperature to 1624°C, and take the boron-titanium alloy molten steel in the medium frequency induction furnace out of the furnace into the ladle containing high-temperature molten steel and rare earth-magnesium-silicon-barium-calcium multi-element alloy in step ①; the amount of boron-titanium alloy molten steel added accounts for 9.2% of the mass fraction of the high-temperature molten steel entering the ladle;

[0043] ③ After the molten steel in step ② is deslagging and standing, when the temperature drops to 1519°C, the molten steel is poured into a crystallizer on a continuous casting machine to be continuously cast into a cylindrical billet with a diameter of Φ550mm, and the cylindrical billet is directly rolled into a cylindrical steel with a diameter of Φ130mm on a rolling mill;

[0044] ④ The cylindrical steel with a diameter of Φ130mm obtained in step ③ is heated to 1180℃ by a walking natural gas heating furnace, kept warm for 160 minutes, and then sheared into a cylinder with a length of 230mm required for a single ball by a rod shearing machine, and the cylinder is rough forged by a CNC hammer, and the deformation amount is controlled at 12% each time. After 4 deformations, a blank steel ball is obtained; then the blank steel ball is finely forged by an air hammer to obtain a Φ180mm steel ball;

[0045] ⑤ Step ④ After fine forging, the surface temperature of the steel ball drops to 883-897°C, and it enters a water pool for quenching. The temperature of the water in the water pool is 67°C, and the mass ratio of water to the steel ball in the water pool is greater than 15:1; after the steel ball is cooled in the water pool for 240 seconds, the steel ball is taken out; and the quenched steel ball is tempered at 200°C for 16 hours, furnace cooled to a temperature below 150°C, and air cooled to room temperature after being taken out of the furnace, a highly hardenable and wear-resistant steel ball can be obtained, and its mechanical properties are shown in Table 1.

[0046] Table 1 Mechanical properties of high hardening wear-resistant steel balls

[0047]

[0048] The wear-resistant steel ball of the present invention uses cheap Si and Mn as the main alloying elements, and does not contain expensive alloying elements such as molybdenum, nickel, tungsten, vanadium, niobium, etc., so it has low cost. The steel ball of the present invention contains a large amount of manganese, nitrogen, boron and other elements that significantly improve the hardenability. The hardenability of the steel ball is significantly improved through the interaction of elements, which can make the Φ160mm-180mm large diameter steel balls completely hardened, reduce the hardness difference between the surface and the center of the steel ball, and thus improve the wear resistance of the steel ball during use. The wear-resistant steel ball of the present invention realizes residual heat treatment after forging, has a wide process adjustable range, is easy to control quality, is quenched and cooled with water, and is energy-saving and environmentally friendly. The wear-resistant steel ball of the present invention has excellent comprehensive mechanical properties. The surface hardness of the Φ160mm-180mm large diameter steel ball exceeds 65HRC, the core hardness exceeds 62HRC, and the impact toughness is greater than 35J / cm 2 The wear-resistant steel ball of the present invention contains a large amount of high-hardness M (M = Cr, Fe) 2B phase, TiB2 and AlN, which significantly improves the wear resistance of the steel ball. Compared with the commonly used wear-resistant steel balls, the wear resistance is improved by more than 40%, and the production cost is similar. The promotion and application of the steel ball of the present invention has good economic and social benefits.

Claims

1. A method for preparing a high hardenability wear-resistant steel ball, characterized in that: The following steps are involved: ① Use electric furnace to melt wear-resistant steel, first mix scrap steel, high nitrogen ferrochrome FeCrN10 and carburizer and heat and melt them, add ferrosilicon and ferromanganese nitride in turn after the molten steel is melted, quickly heat to 1649-1665℃ and add metal aluminum, and control the chemical composition and mass fraction of the molten steel in the furnace to: 0.92-1.06% C, 1.69-1.86% Mn, 0.72-0.91% Si, 0.85-0.98% Cr, 0.18-0.25% N, 0.68-0.77% Al, ≤0.040% P, ≤0.035% S, the balance is Fe and unavoidable impurity elements; After keeping warm for 8-12 minutes, the high-temperature molten steel is taken out of the furnace into a ladle. A rare earth-magnesium-silicon-barium-calcium multi-element alloy preheated at 730-780°C for 120-150 minutes is placed at the bottom of the ladle. The particle size of the rare earth-magnesium-silicon-barium-calcium multi-element alloy is 3-7 mm. The amount of the rare earth-magnesium-silicon-barium-calcium multi-element alloy added accounts for 1.2-1.4% of the mass fraction of the high-temperature molten steel entering the ladle. ② Using a medium frequency induction furnace to melt boron-titanium alloy molten steel; first heat and melt Q235 scrap steel, then raise the temperature to 1603-1622°C, and sequentially add ferrotitanium and ferroboron preheated at 900-980°C for 2-3 hours, and control the chemical composition and mass fraction of the boron-titanium alloy molten steel obtained in the furnace to 8.35-8.82% Ti, 7.21-7.75% B, and the balance is Fe and inevitable residual elements; continue to raise the temperature to 1624-1637°C, and take the boron-titanium alloy molten steel in the medium frequency induction furnace out of the furnace into the ladle containing high-temperature molten steel and rare earth-magnesium-silicon-barium-calcium multi-element alloy in step ①; the amount of boron-titanium alloy molten steel added accounts for 9.2-9.5% of the mass fraction of the high-temperature molten steel entering the ladle; ③ After the molten steel in step ② is deslagging and standing, when the temperature drops to 1503-1519°C, the molten steel is poured into a crystallizer on a continuous casting machine to be continuously cast into a cylindrical billet with a diameter of Φ520-550mm, and the cylindrical billet is directly rolled into a cylindrical steel with a diameter of Φ110-130mm on a rolling mill; ④ The cylindrical steel with a diameter of Φ110-130mm obtained in step ③ is heated to 1120-1180℃ by a walking natural gas heating furnace, kept warm for 160-200 minutes, and then sheared into a cylinder with a length of 215-240mm required for a single ball by a rod shearing machine, and the cylinder is rough forged by a CNC hammer, and the deformation amount is controlled at 11-12% each time. After 4-6 deformations, a blank steel ball is obtained; then the blank steel ball is finely forged by an air hammer to obtain a Φ160mm-180mm steel ball; ⑤ Step ④ After fine forging, the surface temperature of the steel ball drops to 875-897°C, and it enters a water pool for quenching. The temperature of the water in the water pool is 58-67°C, and the mass ratio of water to the steel ball in the water pool is greater than 15:1; after the steel ball is cooled in the water pool for 220-240 seconds, the steel ball is taken out; and the quenched steel ball is tempered at 180-200°C for 16-18 hours, furnace cooled to a temperature below 150°C, and air cooled to room temperature after being taken out of the furnace, a highly hardenable and wear-resistant steel ball can be obtained.

2. The method according to claim 1, characterized in that The chemical composition and mass fraction of the rare earth-magnesium-silicon-barium-calcium multi-element alloy are: 8.26-8.71% RE, 4.84-5.27% Mg, 28.60-29.75% Si, 4.38-4.66% Ba, 5.08-5.79% Ca, and the remainder is Fe and unavoidable impurity elements; the rare earth element includes any one or two of lanthanum and cerium.

3. A high hardenability wear-resistant steel ball prepared according to the method of claim 1 or 2.

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