Nb, V, Ti alloyed light weight wear resistant steel and its preparation method and application

Abstract

This invention provides a lightweight wear-resistant steel alloyed with Nb, V, and Ti, its preparation method, and its applications, belonging to the technical field of lightweight wear-resistant steel. The lightweight wear-resistant steel of this invention, by mass percentage, comprises: Mn 23.0–26.0%, Al 7.5–8.3%, C 1.12–1.25%, Si 0.20–0.25%, Nb 0.05–0.20%, Ti 0.05–0.15%, V 0.05–0.10%, P ≤ 0.03%, S ≤ 0.01%, and the balance Fe. Experimental results show that the lightweight wear-resistant steel provided by this invention has a density ≤ 7.01 g / cm³. 3 Yield strength is 565–654 MPa, tensile strength is 901–985 MPa, elongation is 50.3–58.7%, and KV at -40℃. 2 The impact energy is 97-134J, and the wear resistance is improved by more than 30% with high impact energy.

Description

A lightweight wear-resistant steel alloyed with Nb, V, and Ti, its preparation method, and its application. Technical Field

[0001] This invention relates to the field of lightweight wear-resistant steel technology, and in particular to a lightweight wear-resistant steel alloyed with Nb, V, and Ti, its preparation method, and its application. Background Technology

[0002] Traditional metallurgical and mining operations require the use of large quantities of wear-resistant materials. With the development of technology, traditional basic high-manganese steel, namely cast Mn13, has become outdated in terms of performance requirements. Existing high-manganese steel products are heavy, lack sufficient wear resistance, and are costly, making it difficult to meet the current demands of industrial and mining enterprises for low energy consumption and lightweight development. As research into improving the performance of traditional high-manganese steel continues, research on high-manganese steel with added Al is increasing. By adding the lightweight element Al to the steel, the density is reduced, and it combines with Mn and C to form a Fe-Mn-Al-C system, resulting in a high-strength, high-impact-toughness, lightweight steel.

[0003] However, existing Fe-Mn-Al-C lightweight steels mostly rely on complex processes such as explosive hardening and shot peening to improve their strength and wear resistance. At the same time, these complex production processes increase manufacturing costs, and there are also problems such as insufficient addition of lightweight elements and excessively high density.

[0004] Therefore, providing a lightweight wear-resistant steel with low density, high strength, high plasticity and toughness, high wear resistance and low cost has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a lightweight wear-resistant steel alloyed with Nb, V, and Ti, its preparation method, and its applications. The lightweight wear-resistant steel alloyed with Nb, V, and Ti provided by this invention has low density, high strength, high ductility and toughness, high wear resistance, and low cost.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a lightweight wear-resistant steel alloyed with Nb, V, and Ti, comprising, by mass percentage: Mn 23.0–26.0%, Al 7.5–8.3%, C 1.12–1.25%, Si 0.20–0.25%, Nb 0.10–0.20%, Ti 0.05–0.15%, V 0.05–0.10%, P ≤ 0.03%, S ≤ 0.01%, and the balance Fe.

[0008] Preferably, in the Nb, V, Ti alloyed lightweight wear-resistant steel, the mass content of each element is 0.98≤(0.1Mn+5C) / Al≤1.14.

[0009] This invention provides a method for preparing the Nb, V, and Ti alloyed lightweight wear-resistant steel described in the above technical solution, comprising the following steps:

[0010] (a) The alloy raw materials are melted and then cast to obtain a billet;

[0011] (b) The billet obtained in step (a) is subjected to solution treatment to obtain a solution-treated ingot billet;

[0012] (c) The solution-treated ingot obtained in step (b) is subjected to aging treatment to obtain Nb, V and Ti alloyed lightweight wear-resistant steel.

[0013] Preferably, the casting temperature in step (a) is 1400–1430°C, and the casting time is ≤10 min.

[0014] Preferably, the solution treatment temperature in step (b) is 1070–1090°C, and the solution treatment holding time is 1–2 hours.

[0015] Preferably, the heating method for the solution treatment in step (b) is segmented heating;

[0016] The segmented heating includes a first heating, a first holding, a second heating, a second holding, and a third heating performed sequentially.

[0017] The heating rate for the first heating is 55–60 °C / h;

[0018] The second heating rate is 40–45 °C / h;

[0019] The heating rate for the third heating step is 35–40 °C / h.

[0020] Preferably, the temperature of the first heat preservation is 450-470℃, and the time of the first heat preservation is 0.5-1.5h;

[0021] The second insulation temperature is 630-650℃, and the second insulation time is 0.5-1.5h.

[0022] Preferably, the cooling method for the solution treatment in step (b) is water cooling.

[0023] Preferably, in step (c), the aging treatment temperature is 450–480°C, the aging treatment time is 4–6°C / h, and the heating rate to the aging treatment temperature is 40–45°C / h.

[0024] This invention provides the application of the Nb, V, Ti alloyed lightweight wear-resistant steel described in the above technical solution or the Nb, V, Ti alloyed lightweight wear-resistant steel prepared by the preparation method described in the above technical solution in large mining machinery and transportation equipment.

[0025] This invention provides a lightweight wear-resistant steel alloyed with Nb, V, and Ti, comprising, by mass percentage: Mn 23.0–26.0%, Al 7.5–8.3%, C 1.12–1.25%, Si 0.20–0.25%, Nb 0.10–0.20%, Ti 0.05–0.15%, V 0.05–0.10%, P ≤ 0.03%, S ≤ 0.01%, and the balance Fe. The Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention optimizes and regulates the precipitation behavior of κ carbides by adding Si, Nb, and V elements; the composite addition of Nb and V elements inhibits the precipitation of grain boundary carbides; the addition of Si element produces a high solid solution strengthening effect, improving the mechanical properties of the wear-resistant steel; the composite addition of Nb, V, and Ti elements can generate an appropriate amount of (Nb,V)(C,N) to inhibit the precipitation of grain boundary carbides, forming hard TiC carbide particles, optimizing the precipitation morphology of κ carbides, and avoiding the formation of network N by excessive addition. The Nb, V, and Ti alloys enhance surface impact fatigue resistance and wear resistance under high impact conditions. Controlling the lightweight elements Al, C, Si, V, Ti, and Mn significantly reduces the steel's density, alters the morphology and distribution of carbides, and simultaneously ensures high strength, ductility, toughness, wear resistance, and good overall mechanical properties. By adjusting the composition and content of the lightweight wear-resistant steel, this hardness and high wear resistance can be achieved without complex surface hardening processes such as explosive hardening and shot peening, thus reducing the cost of lightweight wear-resistant steel. Example results show that the Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention has a density ρ ≤ 7.01 g / cm³. 3 Yield strength R eL The tensile strength is 565–654 MPa, and the tensile strength R is... m It has a strength of 901-985 MPa, an elongation of A5 of 50.3-58.7%, and an impact energy of 97-134 J at -40℃. The high impact energy improves wear resistance by more than 30%, and it has low density, high strength, high plasticity and toughness, high wear resistance and low cost. Attached Figure Description

[0026] Figure 1 is a metallographic microstructure of the Nb, V, and Ti alloyed lightweight wear-resistant steel in Example 1 of the present invention;

[0027] Figure 2 is a microstructure of the side of the Nb, V and Ti alloyed lightweight wear-resistant steel after impact wear in Example 1 of the present invention;

[0028] Figure 3 is a SEM image of the high impact energy (4J) wear surface of the Nb, V, Ti alloyed lightweight wear-resistant steel in Example 1 of the present invention.

[0029] Figure 4 is a SEM image of the high-impact energy (4J) wear surface of the high-manganese steel in Comparative Example 1 of the present invention. Detailed Implementation

[0030] This invention provides a lightweight wear-resistant steel alloyed with Nb, V, and Ti, comprising, by mass percentage: Mn 23.0–26.0%, Al 7.5–8.3%, C 1.12–1.25%, Si 0.20–0.25%, Nb 0.10–0.20%, Ti 0.05–0.15%, V 0.05–0.10%, P ≤ 0.03%, S ≤ 0.01%, and the balance Fe.

[0031] The Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, comprises 23.0% to 26.0% Mn, preferably 24.0% to 26.0%, and more preferably 24.5% to 25.0%. In this invention, Mn can expand the austenite phase region, control the ferrite phase region, and improve austenite stability. Excessive brittle phase formation can also play a role in solid solution strengthening, correspondingly increasing the work hardening rate of the steel. High manganese content is beneficial for improving the ductility and toughness of the steel and inhibiting the formation of dual phases. However, as the manganese content increases, grains grow, thermal conductivity decreases, and the steel generates greater internal stress when heated, making it more prone to cracking. Limiting the Mn content to the above-mentioned range ensures that the steel possesses good ductility, toughness, and corrosion resistance.

[0032] The Nb, V, Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, comprises 7.5-8.3% Al, preferably 7.80-8.30%, and more preferably 8.0-8.2%. In this invention, Al can significantly reduce the density of the steel while significantly improving its corrosion resistance and strength. However, Al is a ferrite-forming element; excessively high Al content will narrow the austenite range and promote the brittle δ and κ phases, thus reducing ductility, toughness, and corrosion resistance. Limiting the Al content to the above-mentioned range ensures that the steel possesses good ductility, toughness, and corrosion resistance.

[0033] The Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, comprises 1.12–1.25% C, preferably 1.12–1.20%, and more preferably 1.15–1.17%. In this invention, C is an austenite stabilizing and solid solution strengthening element. Increasing the C content can expand the austenite phase region, improving the hardness and strength of the matrix. However, excessively high C content will generate a large amount of brittle κ phase, which precipitates along grain boundaries, reducing its ductility and toughness. Limiting the C content to the above-mentioned range in this invention ensures that the steel has sufficient wear resistance and a fully austenitic structure.

[0034] The Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, comprises 0.20–0.25% Si, preferably 0.22–0.25%, and more preferably 0.23–0.24%. In this invention, Si is an effective deoxidizing and solid solution strengthening element. Increasing the Si content can improve strength and hardness. However, excessive Si reduces the solubility of C in austenite, leading to an increase in the number of various carbides, thereby reducing mechanical properties and corrosion resistance. Limiting the Si content to the above-mentioned range ensures the mechanical properties and corrosion resistance of the steel.

[0035] The Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, comprises 0.05–0.20% Nb, preferably 0.10–0.20%, and more preferably 0.15–0.20%. In this invention, Nb is a strong carbide-forming element, readily forming fine Nb(C,N) ions at high temperatures. This refines the grains by pinning grain boundaries, thereby improving ductility and toughness. However, excessive Nb can lead to network carbide precipitation at grain boundaries, significantly reducing mechanical properties. Limiting the Nb content to the above-mentioned range ensures the ductility and toughness of the steel.

[0036] The Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, comprises 0.05–0.15% Ti, preferably 0.05–0.10%, and more preferably 0.05–0.08%. In this invention, Ti combines with C, N, and O to form stable compounds, among which TiC and TiN have extremely high melting points and hardness, and can act as hard, wear-resistant phases in the steel, greatly improving the wear resistance of high-manganese steel. However, if the Ti content is too high, too many polygonal and lath-shaped titanium compounds will be formed, reducing the toughness of high-manganese steel. This invention limits the Ti content to the above-mentioned range to ensure the hardness and wear resistance of the steel.

[0037] The Nb, V, Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, comprises 0.05–0.10% V, preferably 0.07–0.10%, and more preferably 0.08–0.09%. In this invention, V can alter the precipitation shape and size of κ carbides, while simultaneously precipitating a new second phase, generating strongly precipitation-strengthened vanadium carbide, offsetting the weakening effect of κ carbide dispersion strengthening. V can also refine grains, producing a fine-grain strengthening effect, thereby improving the mechanical properties of the steel. Limiting the V content to the above-mentioned range in this invention can improve the mechanical properties of the steel.

[0038] The Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, contains P ≤ 0.03%, preferably P ≤ 0.02%. In this invention, P is a harmful element introduced during steelmaking. High carbon content in steel reduces the solubility of P in austenite, easily leading to intergranular precipitation, increasing the likelihood of hot cracking in the workpiece, and reducing the steel's ductility and toughness. Limiting the P content to the above-mentioned range in this invention improves the steel's ductility and toughness.

[0039] The Nb, V, Ti alloyed lightweight wear-resistant steel provided by this invention, by mass percentage, contains S ≤ 0.01%, preferably ≤ 0.005%. In this invention, S readily forms MnS inclusions, increasing hot brittleness and reducing ductility and toughness. Limiting the S content to the above-mentioned range in this invention can improve the ductility and toughness of the steel.

[0040] In this invention, the mass content of Mn, C, and Al is preferably 0.98 ≤ (0.1Mn + 5C) / Al ≤ 1.14, more preferably 1.00 ≤ (0.1Mn + 3C) / Al ≤ 1.10, based on the mass content of each element. In this invention, a stable single-phase austenite temperature range of 1070–1900℃ can be obtained through the compositional control formula between Mn, Al, and C, thereby obtaining a room-temperature fully austenitic structure through quenching at high temperatures. The austenitic structure undergoes work hardening after being subjected to impact loads. The fully austenitic structure can improve the work hardening rate, significantly enhancing the wear resistance of the material under high impact energy.

[0041] The Nb, V, and Ti alloyed lightweight wear-resistant steel provided by this invention optimizes and regulates the precipitation behavior of κ carbides by adding Si, Nb, and V elements; the composite addition of Nb and V elements inhibits the precipitation of grain boundary carbides; the addition of Si element produces a high solid solution strengthening effect, improving the mechanical properties of the wear-resistant steel; the composite addition of Nb, V, and Ti elements can generate an appropriate amount of (Nb,V)(C,N) to inhibit the precipitation of grain boundary carbides, forming hard TiC carbide particles, optimizing the precipitation morphology of κ carbides, and avoiding the formation of network N by excessive addition. b. Carbides and polygonal TiC are used to improve the surface's resistance to impact fatigue and enhance its wear resistance under high impact conditions. By controlling the lightweight elements Al, C, Si, V, Ti and Mn, the density of the steel is significantly reduced, and the morphology and distribution of carbides are changed, while ensuring that the steel has high strength, ductility, toughness, high wear resistance and good comprehensive mechanical properties. By adjusting the composition and content of lightweight wear-resistant steel, the hardness and high wear resistance can be achieved without using complex surface hardening processes such as explosive hardening and shot peening, thus reducing the cost of lightweight wear-resistant steel.

[0042] This invention also provides a method for preparing the Nb, V, Ti alloyed lightweight wear-resistant steel described in the above technical solution, comprising the following steps:

[0043] (a) The alloy raw materials are melted and then cast to obtain a billet;

[0044] (b) The billet obtained in step (a) is subjected to solution treatment to obtain a solution-treated ingot billet;

[0045] (c) The solution-treated ingot obtained in step (b) is subjected to aging treatment to obtain Nb, V and Ti alloyed lightweight wear-resistant steel.

[0046] This invention involves melting alloy raw materials and then casting them to obtain a cast billet.

[0047] In this invention, the preferred alloy raw materials are high-carbon ferromanganese alloy with a ferromanganese content of 65%, metallic manganese with a purity of 99%, metallic aluminum with a purity of 99.95%, a carbon raiser with a carbon content of 98.5% to 99.0%, titanium particles with a purity of 99%, metallic niobium with a purity of 99% (main content 99%), metallic vanadium with a purity of 99%, and industrial pure iron with a purity of 99.99%. Limiting the types and purities of the alloy raw materials to the above-mentioned ranges in this invention can reduce impurities in the alloy.

[0048] In this invention, the melting is preferably vacuum induction melting.

[0049] In this invention, the preferred order of adding the alloy raw materials during smelting is as follows: industrial pure iron and high-carbon ferromanganese alloy are melted, followed by the addition of metallic manganese for further melting, then the addition of a carbon raiser for melting, followed by the sequential addition of titanium granules, metallic niobium, and metallic vanadium for further melting, and finally the addition of metallic aluminum after complete melting. This invention limits the addition of raw materials to the above-mentioned order to ensure a high smelting yield under high Al content conditions.

[0050] In this invention, the aluminum is preferably added in two batches; the amount of the first batch added in the two batches is preferably 45-55% of the total mass of the aluminum; the amount of the second batch added in the two batches is preferably 45-55% of the total mass of the aluminum. This invention, by adding Al in batches for smelting, allows for maximum control over the Al content range.

[0051] In this invention, the casting temperature is preferably 1400–1430°C, more preferably 1410–1420°C; the casting time is preferably ≤10 min, more preferably 5–8 min. This invention obtains the desired billet through casting.

[0052] The present invention does not impose any special limitation on the casting method; any casting method commonly used by those skilled in the art can be used.

[0053] In this invention, the cooling method after casting is preferably air cooling; the air cooling rate is preferably 1-4°C / s. By limiting the cooling method and cooling rate to the above range, this invention can avoid excessively rapid cooling that could cause precipitation of the microstructure, resulting in stress concentration and matrix cracking.

[0054] After obtaining the cast billet, the present invention performs a solution treatment on the cast billet to obtain a solution-treated ingot billet.

[0055] In this invention, the riser of the ingot is preferably removed before solution treatment. There are no special limitations on the riser removal operation; it can be performed using conventional methods employed by those skilled in the art.

[0056] In this invention, the solution treatment temperature is preferably 1070-1090℃, more preferably 1075-1085℃; the solution treatment holding time is preferably 1-2h, more preferably 1.5-2h.

[0057] In this invention, the solution treatment is preferably performed using a segmented heating method. The segmented heating preferably includes a first heating, a first holding, a second heating, a second holding, and a third heating performed sequentially. The heating rate of the first heating is preferably 55–60 °C / h, more preferably 58 °C / h; the heating rate of the second heating is preferably 40–45 °C / h, more preferably 43 °C / h; and the heating rate of the third heating is preferably 35–40 °C / h, more preferably 38 °C / h. This invention reduces the heating rate by approximately 10 °C as the temperature increases during segmented heating, thereby minimizing cracking and segregation that may result from uneven internal and external temperatures during the ingot heating process.

[0058] In this invention, the temperature of the first heat preservation is preferably 450–470°C, more preferably 455–465°C; the time of the first heat preservation is preferably 0.5–1.5 h, more preferably 1 h; the temperature of the second heat preservation is preferably 630–650°C, more preferably 635–645°C; and the time of the second heat preservation is preferably 0.5–1.5 h, more preferably 1 h. By setting the temperature and heat preservation time of each stage of the solution treatment within the above ranges, this invention can improve the effect of solution strengthening and enhance the performance of the steel.

[0059] In this invention, the cooling method for the solution treatment is preferably water cooling; the cooling rate of the water cooling is preferably 15-20°C / s; and the water cooling time is preferably 1-2 minutes. By using water cooling and setting the cooling rate and time within the above ranges, this invention can obtain a uniform austenitic structure, thereby improving the strength and toughness of the steel.

[0060] After obtaining the solution-treated ingot, the present invention performs an aging treatment on the solution-treated ingot to obtain a lightweight wear-resistant steel alloyed with Nb, V and Ti.

[0061] In this invention, the aging treatment temperature is preferably 450–480°C, more preferably 460–470°C; the aging treatment time is preferably 4–6 hours, more preferably 5 hours; and the heating rate to the aging treatment temperature is preferably 40–45°C / hour. Setting the aging treatment time, temperature, and heating rate within the above ranges allows for better aging effects, thereby improving the steel's properties.

[0062] In this invention, the cooling method for the aging treatment is preferably air cooling; the air cooling rate is preferably 1–4 °C / s; and the air cooling time is preferably 6–8 min. This invention improves the strength and toughness of steel by using air cooling and setting the air cooling rate and time within the above ranges.

[0063] This invention can effectively improve the initial hardness of the matrix and enhance the strength, toughness, and wear resistance of Nb, V, and Ti alloyed lightweight wear-resistant steel through solution treatment and aging treatment.

[0064] The present invention also provides the application of the Nb, V, Ti alloyed lightweight wear-resistant steel described in the above technical solution or the Nb, V, Ti alloyed lightweight wear-resistant steel prepared by the preparation method described in the above technical solution in large mining machinery and transportation equipment.

[0065] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0066] Example 1

[0067] A lightweight wear-resistant steel alloyed with Nb, V, and Ti has the following composition by mass percentage: Mn 23.0%, Al 7.5%, C 1.25%, Si 0.20%, Nb 0.10%, Ti 0.1%, V 0.05%, P 0.03%, S 0.01%, and the balance Fe; wherein (0.1Mn+5C) / Al=1.14;

[0068] The method for preparing the Nb, V, Ti alloyed lightweight wear-resistant steel comprises the following steps:

[0069] (a) The steel is smelted in a vacuum induction furnace. According to the chemical composition of the steel, before smelting, 99.99% pure industrial iron and 65% high carbon ferromanganese alloy are added. The temperature is raised by electricity. After the raw materials are melted, 99% pure metallic manganese is added. After the metallic manganese is melted, a carbon raiser is added and melted. Then, 99% pure titanium particles, 99% pure metallic niobium (main content 99%), and 99% pure metallic vanadium are added. After the melting is complete, 50% of the total mass of metallic aluminum and 99.95% pure metallic aluminum are added. Half an hour before the steel is tapped, 50% of the total mass of metallic aluminum and 99.95% pure metallic aluminum are added. After all the raw materials are melted, the temperature of the molten steel is controlled at 1420°C and cast into a billet. The casting time is 7 minutes. After the casting is completed and the billet solidifies, it is demolded and air-cooled to room temperature at a cooling rate of 4°C / s.

[0070] (b) After removing the riser from the billet obtained in step (a), heat it to 460°C at a heating rate of 58°C / h and hold it for 1 hour, then heat it to 640°C at a heating rate of 43°C / h and hold it for 1 hour, then heat it to 1080°C at a heating rate of 38°C / h and hold it for 2 hours. After the billet is completely homogeneous, it is taken out of the furnace and sent to a water tank for water cooling. The cooling rate of the water cooling is 18°C / s and the water cooling time is 1 minute to obtain a solution-treated ingot.

[0071] (c) The solution-treated billet obtained in step (b) is heated to 465°C at a heating rate of 43°C / h and held for 5 hours, then air-cooled to room temperature at a cooling rate of 4°C / s for 6 minutes to obtain Nb, V and Ti alloyed lightweight wear-resistant steel.

[0072] The performance data of the Nb, V, and Ti alloyed lightweight wear-resistant steel in Example 1 are shown in Table 1. The high impact energy (4J) wear resistance is 10.21g. -1 This represents a 31% increase compared to control 1.

[0073] Example 2

[0074] A lightweight wear-resistant steel alloyed with Nb, V, and Ti has the following composition by mass percentage: Mn 24.5%, Al 8.0%, C 1.17%, Si 0.20%, Nb 0.05%, Ti 0.15%, V 0.10%, P 0.03%, S 0.01%, and the balance Fe; wherein (0.1Mn+5C) / Al=1.04;

[0075] The method for preparing the Nb, V, Ti alloyed lightweight wear-resistant steel comprises the following steps:

[0076] (a) The steel is smelted in a vacuum induction furnace. According to the chemical composition of the steel, before smelting, 99.99% pure industrial iron and 65% high carbon ferromanganese alloy are added. The temperature is raised by electricity. After the raw materials are melted, 99% pure metallic manganese is added. After the metallic manganese is melted, a carbon raiser is added and melted. Then, 99% pure titanium particles, 99% pure metallic niobium (main content 99%), and 99% pure metallic vanadium are added. After the melting is complete, 50% of the total mass of metallic aluminum and 99.95% pure metallic aluminum are added. Half an hour before the steel is tapped, 50% of the total mass of metallic aluminum and 99.95% pure metallic aluminum are added. After all the raw materials are melted, the temperature of the molten steel is controlled at 1420°C and cast into a billet. The casting time is 7 minutes. After the casting is completed and the billet solidifies, it is demolded and air-cooled to room temperature at a cooling rate of 4°C / s.

[0077] (b) After removing the riser from the billet obtained in step (a), heat it to 460°C at a heating rate of 58°C / h and hold it for 1 hour, then heat it to 640°C at a heating rate of 43°C / h and hold it for 1 hour, then heat it to 1080°C at a heating rate of 38°C / h and hold it for 2 hours. After the billet is completely homogeneous, it is taken out of the furnace and sent to a water tank for water cooling. The cooling rate of the water cooling is 18°C / s and the water cooling time is 1 minute to obtain a solution-treated ingot.

[0078] (c) The solution-treated billet obtained in step (b) is heated to 465°C at a heating rate of 43°C / h and held for 5 hours, then air-cooled to room temperature at a cooling rate of 4°C / s for 7 minutes to obtain Nb, V and Ti alloyed lightweight wear-resistant steel.

[0079] The performance data of the Nb, V, and Ti alloyed lightweight wear-resistant steel in Example 2 are shown in Table 1. The high impact energy (4J) wear resistance is 10.34g. -1 This represents a 33% increase compared to control 1.

[0080] Example 3

[0081] A lightweight wear-resistant steel alloyed with Nb, V, and Ti has the following composition by mass percentage: Mn 26.0%, Al 8.3%, C 1.12%, Si 0.25%, Nb 0.2%, Ti 0.05%, V 0.1%, P 0.028%, S 0.01%, and the balance Fe; wherein, (0.1Mn+5C) / Al=0.988;

[0082] The method for preparing the Nb, V, Ti alloyed lightweight wear-resistant steel comprises the following steps:

[0083] (a) The steel is smelted in a vacuum induction furnace. According to the chemical composition of the steel, before smelting, 99.99% pure industrial iron and 65% high carbon ferromanganese alloy are added. The temperature is raised by electricity. After the raw materials are melted, 99% pure metallic manganese is added. After the metallic manganese is melted, a carbon raiser is added and melted. Then, 99% pure titanium particles, 99% pure metallic niobium (main content 99%), and 99% pure metallic vanadium are added. After the melting is complete, 50% of the total mass of metallic aluminum and 99.95% pure metallic aluminum are added. Half an hour before the steel is tapped, 50% of the total mass of metallic aluminum and 99.95% pure metallic aluminum are added. After all the raw materials are melted, the temperature of the molten steel is controlled at 1420°C and cast into a billet. The casting time is 2 minutes. After the casting is completed and the billet solidifies, it is demolded and air-cooled to room temperature at a cooling rate of 4°C / s.

[0084] (b) After removing the riser from the billet obtained in step (a), heat it to 460°C at a heating rate of 58°C / h and hold it for 1 hour, then heat it to 640°C at a heating rate of 43°C / h and hold it for 1 hour, then heat it to 1080°C at a heating rate of 38°C / h and hold it for 2 hours. After the billet is completely homogeneous, it is taken out of the furnace and sent to a water tank for water cooling. The cooling rate of the water cooling is 18°C / s and the water cooling time is 1 minute to obtain a solution-treated ingot.

[0085] (c) The solution-treated billet obtained in step (b) is heated to 465°C at a heating rate of 43°C / h and held for 5 hours, then air-cooled to room temperature at a cooling rate of 4°C / s for 7 minutes to obtain Nb, V and Ti alloyed lightweight wear-resistant steel.

[0086] The performance data of the Nb, V, and Ti alloyed lightweight wear-resistant steel in Example 3 are shown in Table 1. The high impact energy (4J) wear resistance is 10.70g. -1 This represents a 37% increase compared to control 1.

[0087] Comparative Example 1

[0088] A high-manganese steel, by mass percentage, has the following composition: Mn 13.3%, C 1.1%, Si 0.35%, Cr 0.5%, Mo 1.0%, P 0.03%, S 0.01%, and the balance Fe;

[0089] The method for preparing the high-manganese steel comprises the following steps:

[0090] (a) The steel is smelted in a vacuum induction furnace. According to the chemical composition of the steel, before smelting, 99.99% pure industrial iron and 65% high carbon ferromanganese alloy are added. The temperature is raised by electricity. After the raw materials are melted, 99% pure metallic manganese is added. After the metallic manganese is melted, 63% molybdenum alloy and 95% micro carbon ferrochrome alloy are added. After all the raw materials are melted, the temperature of the molten steel is controlled at 1440°C and cast into a billet. The casting time is 8 minutes. After the billet solidifies, it is demolded and air-cooled to room temperature at a cooling rate of 4°C / s.

[0091] (b) After removing the riser from the billet obtained in step (a), heat it to 480°C at a heating rate of 45°C / h and hold it for 1 hour. Then heat it to 650°C at a heating rate of 25°C / h and hold it for 2 hours. Then heat it to 1080°C at a heating rate of 40°C / h and hold it for 2 hours. After the billet is completely homogeneous, it is taken out of the furnace and sent to a water tank for water cooling. First, it is cooled to 650°C at a cooling rate of 10°C / s, and then cooled to room temperature at a cooling rate of 15°C / s to obtain a solution-treated ingot.

[0092] (c) The solution-treated billet obtained in step (b) is heated to 350°C at a heating rate of 40°C / h and held for 4 hours, then air-cooled to room temperature at a cooling rate of 3°C / s for 6 minutes to obtain high-manganese steel.

[0093] The performance data of the high-manganese steel in Comparative Example 1 are shown in Table 1. The high impact energy (4J) and wear resistance are 7.77g. -1 .

[0094] The wear-resistant steels prepared in Examples 1-3 and Comparative Example 1 were tested for tensile strength, yield strength, elongation, impact performance at -40℃, and wear resistance. The specific testing methods are as follows: Tensile strength, yield strength, and elongation were tested according to national standards GB / T 1231-2006 and GB / T 228.1-2010 "Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method". Round bar tensile specimens were taken from one-quarter of the ingot's length from the core, and a tensile test was conducted at room temperature on a tensile testing machine at a tensile rate of 3 mm / min. Impact performance was tested according to GB / T 229-2007 "Metallic Materials - Charpy Pendulum Impact Test Method". Standard impact specimens were taken from one-quarter of the ingot's length from the core, and an impact test was conducted at -40℃. Wear resistance was tested using an MLD-10 impact wear testing machine at room temperature with an impact load of 4 J and a flow rate of 20 kg / h.

[0095] The properties of the Nb, V, Ti alloyed lightweight wear-resistant steels prepared in Examples 1-4 and Comparative Example 1 are shown in Table 1:

[0096] Table 1. Properties of Nb, V, Ti alloyed lightweight wear-resistant steels prepared in Examples 1-3 and Comparative Example 1

[0097]

[0098] Figure 1 shows the metallographic microstructure of the Nb, V, and Ti alloyed lightweight wear-resistant steel in Example 1 of this invention; Figure 2 shows the microstructure of the side surface of the Nb, V, and Ti alloyed lightweight wear-resistant steel after impact wear in Example 1; Figure 3 shows the SEM image of the high impact energy (4J) wear surface of the Nb, V, and Ti alloyed lightweight wear-resistant steel in Example 1; Figure 4 shows the SEM image of the high impact energy (4J) wear surface of the high manganese steel in Comparative Example 1.

[0099] After heat treatment, the matrix structure of the embodiments was austenitic with a small amount of κ carbides. Taking Example 1 as an example, under aging conditions, the metallographic microstructure was austenitic with a small amount of κ carbides and other dispersed carbides (Figure 1). Under high impact load, the aged new lightweight wear-resistant steel underwent plastic deformation, and the surface morphology contained pits caused by fatigue spalling (Figure 3). Its main wear mechanism was plastic deformation and fatigue spalling. Comparative Example 1 was a traditional high-manganese steel (Mn13). After being subjected to high impact load, a small number of microcracks were generated inside. When these microcracks extended to the surface, spalling pits were generated. Therefore, the comparative example had poor plastic deformation resistance, the surface was prone to spalling, the hardened layer lasted for a shorter time, and the wear resistance decreased. Its wear mechanism was fatigue spalling and crack propagation (Figure 4). Therefore, the wear resistance of the comparative example was much lower than that of the embodiments of the present invention.

[0100] The Nb, V, and Ti alloyed lightweight wear-resistant steel prepared by this invention has a density ρ ≤ 7.01 g / cm³. 3 The matrix structure is austenite + carbides (Figure 1), and the yield strength R eL With a tensile strength of 565–654 MPa and a tensile strength R m The strength is 901–985 MPa, the elongation A5 is 50.3–58.7%, and the KV2 at -40℃ is 97–134 J. After impact wear, the surface undergoes work hardening, and the hardness is significantly increased. The microstructure shows obvious dislocation line pile-up (Figure 2). The wear resistance is more than 30% higher than that of the comparative example. It has the characteristics of low density, high strength, high plasticity and toughness, and high wear resistance. Moreover, it is low in cost and simple in production process.

[0101] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lightweight wear-resistant steel alloyed with Nb, V, and Ti, comprising, by mass percentage: Mn 23.0~26.0%, Al 7.5~8.3%, C 1.12~1.25%, Si 0.20~0.25%, Nb 0.05~0.20%, Ti 0.05~0.15%, V 0.05~0.10%, P≤0.03%, S≤0.01%, and the balance Fe; the method for preparing the Nb, V, and Ti alloyed lightweight wear-resistant steel includes the following steps: (a) The alloy raw materials are melted and cast to obtain a billet; (b) The billet obtained in step (a) is subjected to solution treatment to obtain a solution-treated ingot; (c) The solution-treated ingot obtained in step (b) is subjected to aging treatment to obtain a lightweight wear-resistant steel alloyed with Nb, V, and Ti; the heating method for the solution treatment in step (b) is segmented heating; the segmented heating includes a first heating, a first holding, a second heating, a second holding, and a third heating in sequence; the heating rate of the first heating is 55~60℃ / h; The second heating rate is 40~45℃ / h; the third heating rate is 35~40℃ / h; the first holding temperature is 450~470℃, and the first holding time is 0.5~1.5h; the second holding temperature is 630~650℃, and the second holding time is 0.5~1.5h; the aging treatment temperature in step (c) is 450~480℃, the aging treatment time is 4~6h, and the heating rate to the aging treatment temperature is 40~45℃ / h.

2. The Nb, V, Ti alloyed lightweight wear-resistant steel according to claim 1, characterized in that, In the Nb, V, Ti alloyed lightweight wear-resistant steel, the mass content of each element is 0.98≤(0.1Mn+5C) / Al≤1.

14.

3. A method for preparing the Nb, V, Ti alloyed lightweight wear-resistant steel according to claim 1 or 2, comprising the following steps: (a) The alloy raw materials are melted and cast to obtain a billet; (b) The billet obtained in step (a) is subjected to solution treatment to obtain a solution-treated ingot; (c) The solution-treated ingot obtained in step (b) is subjected to aging treatment to obtain a lightweight wear-resistant steel alloyed with Nb, V, and Ti; the heating method for the solution treatment in step (b) is segmented heating; the segmented heating includes a first heating, a first holding, a second heating, a second holding, and a third heating in sequence; the heating rate of the first heating is 55~60℃ / h; The second heating rate is 40~45℃ / h; the third heating rate is 35~40℃ / h; the first holding temperature is 450~470℃, and the first holding time is 0.5~1.5h; the second holding temperature is 630~650℃, and the second holding time is 0.5~1.5h; the aging treatment temperature in step (c) is 450~480℃, the aging treatment time is 4~6h, and the heating rate to the aging treatment temperature is 40~45℃ / h.

4. The preparation method according to claim 3, characterized in that, In step (a), the casting temperature is 1400~1430℃ and the casting time is ≤10min.

5. The preparation method according to claim 3, characterized in that, The solution treatment temperature in step (b) is 1070~1090℃, and the heat treatment time is 1~2h.

6. The preparation method according to claim 3, characterized in that, The cooling method for the solution treatment in step (b) is water cooling.

7. The application of the Nb, V, Ti alloyed lightweight wear-resistant steel according to claim 1 or 2, or the Nb, V, Ti alloyed lightweight wear-resistant steel prepared by the preparation method according to any one of claims 3 to 6, in large mining machinery and transportation equipment.

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