A niobium microalloyed high-performance wear-resistant steel and a preparation method thereof

Abstract

The application discloses niobium microalloyed high-performance wear-resistant steel and a preparation method thereof, and belongs to the technical field of wear-resistant steel production. The alloy raw material is used for smelting, casting, heating, rolling, cooling, high-pressure treatment, quenching, high-pressure treatment and tempering, so that the grains are refined and the carbides with a diameter of 1-3 microns are precipitated under the premise of guaranteeing the high-strength martensite structure. The niobium microalloyed high-performance wear-resistant steel prepared has a hardness of greater than or equal to 1150HV and a tensile strength of greater than or equal to 1550MPa. The wear-resistant steel has high wear resistance and excellent mechanical properties, is suitable for large-scale industrial production and popularization and use, and can be widely applied in engineering fields and manufacturing industries.

Description

Technical Field

[0001] The invention belongs to the technical field of wear-resistant steel production, and particularly relates to a niobium microalloyed high-performance wear-resistant steel and a preparation method thereof. Background Art

[0002] Wear-resistant steel, characterized by high strength and wear resistance, is widely used as a component in mining machinery, construction machinery, metallurgical equipment, coal mining machinery, and other fields. Currently, there are three main types of wear-resistant steel used in mining machinery both domestically and internationally: high-manganese steel, high-chromium cast iron, and alloy wear-resistant steel. High-manganese steel offers excellent toughness but a short lifespan; high-chromium cast iron offers excellent wear resistance but poor machinability; and low-alloy wear-resistant steel offers excellent machinability and wear resistance, with a service life several times that of traditional structural steel plates. The production process is simple, typically employing post-rolling quenching and tempering, or strengthening through controlled rolling and controlled cooling.

[0003] Low cost, short process, and high performance are the inevitable trends in the development of the steel industry. However, existing low-alloy wear-resistant steels generally use a combination of two or more alloying elements, especially precious alloying elements such as Mo, Cr, and Ni. Although this improves performance, it also increases production costs, making it unfavorable for large-scale production. Therefore, microalloying of wear-resistant steels is an important development trend.

[0004] Chinese patent application CN103789655A discloses a method for producing Nb-alloyed high-strength wear-resistant steel plate by in-line quenching, with a carbon content of 0.25-0.45 wt.%, a quenching temperature of 800-900°C, and a tempering temperature of 100-300°C. While this method improves the strength and toughness of NM500 wear-resistant steel plate, achieving a surface Brinell hardness of at least 520 HB, the addition of multiple alloying elements, including Mn, Ti, B, Cr, and Nb, results in high production costs, hindering the widespread application of wear-resistant steel.

[0005] Chinese patent application CN101775545A discloses a low-alloy, high-strength, high-toughness wear-resistant steel plate and its manufacturing method. The steel has a carbon content of 0.15-0.27 wt.%. The steel is prepared using a composite microalloying process involving Cr, Mo, Nb, and Ti, through smelting, casting, heating, rolling, cooling, quenching, and tempering. The quenching temperature is Ac3+0-100°C, and the tempering temperature is 150-350°C. This method effectively improves the strength and toughness of the wear-resistant steel, achieving a hardness greater than 450 HB. However, the addition of multiple precious alloying elements increases the difficulty of controlling the smelting process, raising the alloy cost and making it unsuitable for large-scale industrial production.

[0006] Chinese patent application CN1033845A discloses a high-strength and toughness low-carbon microalloyed cast steel, wherein the carbon content is 0.06-0.18wt.%, and the cast steel is prepared by normalizing-tempering or homogenizing annealing-normalizing-tempering process using Mn, Ti, Nb, rare earth elements, etc. The cast steel has high tensile strength and yield strength, high plasticity and toughness, and good processing properties. However, due to the low carbon content, there are problems such as low strength, low hardness, and poor wear resistance. In addition, the cast steel uses Mn, Ti, Nb, rare earth elements, etc. as alloying elements, resulting in high production costs and being unfavorable for industrial production.

[0007] In summary, wear-resistant steel is generally prepared by adding multiple alloying elements to low-carbon steel and combining it with a quenching and tempering process. The resulting wear-resistant steel has a low Vickers hardness (less than 600HV), a complex production process, and high alloy costs. Furthermore, carbon is the most basic strengthening element in steel, and interstitial solid solution strengthening of carbon atoms is the primary mechanism for strengthening quenched martensite in quenched steel. However, under the existing wear-resistant steel composition system and heat treatment process conditions, the hardness and strength of high-carbon steel are not significantly improved. Summary of the Invention

[0008] To address the shortcomings of the prior art, the present invention provides a niobium microalloyed high-performance wear-resistant steel and its preparation method. This invention incorporates high-pressure technology and Nb microalloying techniques based on high-carbon steel, combined with traditional quenching and tempering processes to address the current issues of high alloying element consumption, complex manufacturing processes, and low hardness levels in wear-resistant steel.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A method for preparing niobium microalloyed high-performance wear-resistant steel, comprising:

[0011] (1) preparing the ingredients according to the chemical composition of niobium microalloyed high performance wear-resistant steel, then smelting and casting into ingots;

[0012] (2) subjecting the ingot to homogenization treatment, rolling treatment, and cooling in sequence to obtain a wear-resistant steel plate;

[0013] (3) Apply pressure to the six sides of the wear-resistant steel plate at the same time and heat it to the quenching temperature and keep it warm. After the end, quench it to room temperature;

[0014] (4) Applying pressure to the six sides of the quenched wear-resistant steel plate simultaneously and heating it to the tempering temperature and keeping it warm, and then air-cooling it to room temperature to obtain niobium microalloyed high-performance wear-resistant steel.

[0015] As a preferred embodiment of the present invention, the niobium microalloyed high performance wear-resistant steel comprises the following elements in percentage by mass: C: 0.70-0.90 wt.%, Nb: 0.01-0.05 wt.%, and the remainder being Fe and unavoidable impurities.

[0016] In the present invention, the C content is lower than 0.70wt.%, which will lead to a decrease in performance hardness and tensile strength. Too high a C content will promote the formation of secondary cementite, reduce plastic toughness, and make the material brittle, so the C content should not be greater than 0.90wt.%. In the present invention, the Nb content is less than 0.01wt.%, which is difficult to play a significant role and does not improve the wear resistance and plastic toughness of wear-resistant steel. Compared with other elements (Ti, V, etc.), the present invention adopts a single Nb element for microalloying, combined with high pressure technology and high carbon, and a small amount of carbide particles precipitated at high temperature can also pin the original austenite grain boundaries to a large extent to inhibit the growth of austenite grains; and it is not easy to form inclusions or alloy cementite, which will reduce the plastic toughness of the material and make it brittle. Too high a Nb content will increase the undissolved phase formed at the quenching temperature and make it coarse in size, which will have an adverse effect on the wear resistance and plastic toughness of wear-resistant steel, and cause a waste of niobium iron resources. Moreover, the coarsening of niobium-containing carbides will increase the occurrence of defects such as cracks and reduce the processing performance and plastic toughness of steel. Therefore, the Nb content should not exceed 0.05 wt.%.

[0017] As a preferred embodiment of the present invention, in steps (3) and (4), the applied pressure is 3-5 GPa.

[0018] The present invention employs a pressure of 3-5 GPa to modify the atomic-scale crystal structure and physicochemical properties, thereby improving the hardness and ductility of the steel. However, applying a pressure less than 3 GPa fails to affect the atomic-scale crystal structure and physicochemical properties, resulting in insignificant improvements in the steel's hardness and strength. Pressures greater than 5 GPa further promote carbide precipitation, resulting in coarsening and reducing the material's ductility.

[0019] As a preferred embodiment of the present invention, the temperature of the homogenization treatment is 1200-1250° C., and the holding time is 1-3 hours.

[0020] As a preferred embodiment of the present invention, the rolling process is multi-pass rolling, the starting rolling temperature is 1000-1050°C, the finishing rolling temperature is 760-800°C, and the deformation amount is 70%-90%.

[0021] As a preferred embodiment of the present invention, the quenching temperature is 950-1150° C., the holding time is 0.5-1 h, and the cooling rate of quenching is above 50° C. / s.

[0022] As a preferred embodiment of the present invention, the tempering temperature is 200-300° C., and the holding time is 0.5-1 h.

[0023] The present invention also claims protection for the niobium microalloyed high-performance wear-resistant steel prepared by the preparation method of the niobium microalloyed high-performance wear-resistant steel, wherein the microstructure of the niobium microalloyed high-performance wear-resistant steel comprises tempered martensite and carbides.

[0024] As a preferred embodiment of the present invention, the carbide particle size is 1-3 μm.

[0025] As a preferred embodiment of the present invention, the niobium microalloyed high performance wear-resistant steel has a hardness of ≥1150 HV and a tensile strength of ≥1550 MPa.

[0026] Compared with existing technologies, the present invention offers the following advantages: It combines high-carbon steel, high-pressure technology, and microalloying of the single alloying element Nb with traditional quenching and tempering processes to refine grains and promote the precipitation of carbides with diameters of 1-3 μm, while maintaining a high-strength martensitic structure. This results in a niobium-microalloyed, high-performance wear-resistant steel with significantly improved hardness and tensile strength, achieving a hardness of ≥1150 HV and a tensile strength of ≥1550 MPa. This wear-resistant steel exhibits high wear resistance and excellent mechanical properties, making it suitable for large-scale industrial production and widespread use, with potential applications in engineering and manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the metallographic structure morphology of the niobium microalloyed high performance wear-resistant steel prepared in Example 1.

[0028] Figure 2 This is the metallographic structure morphology of the niobium microalloyed wear-resistant steel prepared in Comparative Example 1. DETAILED DESCRIPTION

[0029] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0030] Example 1

[0031] The chemical composition of a niobium microalloyed high-performance wear-resistant steel is as follows: C: 0.86 wt.%, Nb: 0.03 wt.%, and the rest is Fe and inevitable impurities.

[0032] A method for preparing niobium microalloyed high-performance wear-resistant steel comprises the following steps:

[0033] S1. Smelting and casting process:

[0034] The raw materials were weighed, mixed, and smelted according to the chemical composition mass percentage of the niobium microalloyed high-performance wear-resistant steel described in this embodiment. After smelting, the steel was cast into 150×150 mm continuous casting billets.

[0035] S2. Homogenization process:

[0036] The continuous casting billet in step S1 is subjected to heating homogenization treatment, with a heating temperature of 1250° C. and a holding time of 1 h, and the microstructure is austenite.

[0037] S3, rolling process:

[0038] The continuous casting billet after the heating and homogenization treatment in step S2 is subjected to multiple rolling passes, with the starting rolling temperature being 1050° C., the finishing rolling temperature being 800° C., and the deformation amount being 80%, to obtain a wear-resistant steel plate.

[0039] S4, cooling process:

[0040] The wear-resistant steel plate in step S3 is air-cooled to room temperature.

[0041] S5, quenching process:

[0042] The wear-resistant steel plate in step S4 is placed in a six-sided press and pressure is applied to all six sides at the same time. The applied pressure is 5 GPa, and it is heated to 1100°C in the six-sided press and kept warm for 0.5h. After the end, it is quenched to room temperature and the cooling rate is controlled at 100°C / s.

[0043] S6, tempering process:

[0044] The wear-resistant steel plate quenched in step S5 was heated to 250° C. under a high pressure of 5 GPa in a six-sided top press, tempered and kept warm for 0.5 h, and then air-cooled to room temperature to obtain niobium microalloyed high-performance wear-resistant steel.

[0045] like Figure 1 As shown in FIG, the microstructure of the niobium microalloyed high performance wear-resistant steel is tempered martensite and carbide, the carbide particle size is 1-3 μm, the hardness is ≥1310 HV, and the tensile strength is ≥1800 MPa.

[0046] Example 2

[0047] The chemical composition of a niobium microalloyed high-performance wear-resistant steel is as follows: C: 0.82 wt.%, Nb: 0.03 wt.%, and the rest is Fe and inevitable impurities.

[0048] The only difference between the method for preparing niobium microalloyed high-performance wear-resistant steel and Example 1 is that the ingredients in S1 are prepared according to the chemical composition of the niobium microalloyed high-performance wear-resistant steel described in Example 2.

[0049] The microstructure of the niobium microalloyed high-performance wear-resistant steel is tempered martensite and carbide, the carbide particle size is 1-3 μm, the hardness is ≥1270 HV, and the tensile strength is ≥1700 MPa.

[0050] Example 3

[0051] The chemical composition of a niobium microalloyed high-performance wear-resistant steel is as follows: C: 0.77 wt.%, Nb: 0.03 wt.%, and the rest is Fe and inevitable impurities.

[0052] The only difference between the method for preparing niobium microalloyed high-performance wear-resistant steel and Example 1 is that the ingredients in S1 are prepared according to the chemical composition of the niobium microalloyed high-performance wear-resistant steel described in Example 3.

[0053] The microstructure of the niobium microalloyed high-performance wear-resistant steel is tempered martensite and carbide, the carbide particle size is 1-3 μm, the hardness is ≥1220 HV, and the tensile strength is ≥1600 MPa.

[0054] Example 4

[0055] The chemical composition of a niobium microalloyed high-performance wear-resistant steel is as follows: C: 0.70 wt.%, Nb: 0.05 wt.%, and the rest is Fe and inevitable impurities.

[0056] A method for preparing niobium microalloyed high-performance wear-resistant steel comprises the following steps:

[0057] S1. Smelting and casting process:

[0058] The raw materials were weighed, mixed, and smelted according to the chemical composition mass percentage of the niobium microalloyed high-performance wear-resistant steel described in this embodiment. After smelting, the steel was cast into 150×150 mm continuous casting billets.

[0059] S2. Homogenization process:

[0060] The continuous casting billet in step S1 is subjected to heating homogenization treatment, with a heating temperature of 1200° C. and a holding time of 3 hours, and the microstructure is austenite.

[0061] S3, rolling process:

[0062] The continuous casting billet after the heating and homogenization treatment in step S2 is subjected to multiple rolling passes, with the starting rolling temperature being 1000° C., the finishing rolling temperature being 760° C., and the deformation amount being 70%, to obtain a wear-resistant steel plate.

[0063] S4, cooling process:

[0064] The wear-resistant steel plate in step S3 is air-cooled to room temperature.

[0065] S5, quenching process:

[0066] The wear-resistant steel plate in step S4 is placed in a six-sided press and pressure is applied to all six sides at the same time. The applied pressure is 5 GPa, and it is heated to 1150°C in the six-sided press and kept warm for 0.8h. After the end, it is quenched to room temperature and the cooling rate is controlled at 50°C / s.

[0067] S6, tempering process:

[0068] The wear-resistant steel plate quenched in step S5 is heated to 200° C. under a high pressure of 5 GPa in a six-sided top press, tempered and kept warm for 1 hour, and then air-cooled to room temperature to obtain niobium microalloyed high-performance wear-resistant steel.

[0069] The microstructure of the niobium microalloyed high-performance wear-resistant steel is tempered martensite and carbide, the carbide particle size is 1-3 μm, the hardness is ≥1180 HV, and the tensile strength is ≥1570 MPa.

[0070] Example 5

[0071] The chemical composition of a niobium microalloyed high-performance wear-resistant steel is as follows: C: 0.90 wt.%, Nb: 0.01 wt.%, and the rest is Fe and inevitable impurities.

[0072] A method for preparing niobium microalloyed high-performance wear-resistant steel comprises the following steps:

[0073] S1. Smelting and casting process:

[0074] The raw materials were weighed, mixed, and smelted according to the chemical composition mass percentage of the niobium microalloyed high-performance wear-resistant steel described in this embodiment. After smelting, the steel was cast into 150×150 mm continuous casting billets.

[0075] S2. Homogenization process:

[0076] The continuous casting billet in step S1 is subjected to heating homogenization treatment, with a heating temperature of 1250° C. and a holding time of 1 h, and the microstructure is austenite.

[0077] S3, rolling process:

[0078] The continuous casting billet after the heating and homogenization treatment in step S2 is subjected to multiple rolling passes, with the starting rolling temperature being 1050° C., the finishing rolling temperature being 800° C., and the deformation amount being 90%, to obtain a wear-resistant steel plate.

[0079] S4, cooling process:

[0080] The wear-resistant steel plate in step S3 is air-cooled to room temperature.

[0081] S5, quenching process:

[0082] The wear-resistant steel plate in step S4 is placed in a six-sided press and pressure is applied to all six sides at the same time. The applied pressure is 5 GPa, and it is heated to 950°C in the six-sided press and kept warm for 1 hour. After the end, it is quenched to room temperature and the cooling rate is controlled at 150°C / s.

[0083] S6, tempering process:

[0084] The wear-resistant steel plate quenched in step S5 is heated to 300° C. under a high pressure of 5 GPa in a six-sided top press, tempered and kept warm for 0.5 h, and then air-cooled to room temperature to obtain niobium microalloyed high-performance wear-resistant steel.

[0085] The microstructure of the niobium microalloyed high-performance wear-resistant steel is tempered martensite and carbide, the carbide particle size is 1-3 μm, the hardness is ≥1350 HV, and the tensile strength is ≥1850 MPa.

[0086] Comparative Example 1

[0087] The chemical composition of a niobium microalloyed wear-resistant steel is as follows: C: 0.86 wt.%, Nb: 0.03 wt.%, and the rest is Fe and inevitable impurities.

[0088] A method for preparing niobium microalloyed wear-resistant steel comprises the following steps:

[0089] S1. Smelting and casting process:

[0090] The raw materials were weighed, mixed, and smelted according to the chemical composition mass percentage of the niobium microalloyed wear-resistant steel described in this embodiment. After smelting, the steel was cast into 150×150 mm continuous casting billets.

[0091] S2. Homogenization process:

[0092] The continuous casting billet in step S1 is subjected to a heating homogenization treatment, with a heating temperature of 1250° C. and a holding time of 1 hour, and the microstructure is austenite.

[0093] S3, rolling process:

[0094] The continuous casting billet after the heating and homogenization treatment in step S2 is subjected to multiple rolling passes, with the starting rolling temperature being 1050° C., the finishing rolling temperature being 800° C., and the deformation amount being 80%, to obtain a wear-resistant steel plate.

[0095] S4, cooling process:

[0096] The wear-resistant steel plate in step S3 is air-cooled to room temperature.

[0097] S5, quenching process:

[0098] The wear-resistant steel plate in step S4 is heated to 1100° C. and kept at this temperature for 0.5 h. After heating, it is quenched to room temperature, and the cooling rate is controlled at 100° C. / s.

[0099] S6, tempering process:

[0100] The wear-resistant steel plate after quenching in step S5 is heated to 250° C. and tempered and kept at this temperature for 0.5 h. After tempering, the plate is air-cooled to room temperature to obtain niobium microalloyed wear-resistant steel.

[0101] The microstructure of the niobium microalloyed wear-resistant steel prepared in this comparative example is as follows: Figure 2 As shown, the structure is tempered martensite, the hardness is ≥970HV, and the tensile strength is ≥1240MPa.

[0102] Comparative Example 2

[0103] The chemical composition of a niobium microalloyed wear-resistant steel is as follows: C: 0.82 wt.%, Nb: 0.03 wt.%, and the rest is Fe and inevitable impurities.

[0104] A method for preparing niobium microalloyed wear-resistant steel comprises the following steps:

[0105] S1. Smelting and casting process:

[0106] The raw materials were weighed, batched, and smelted according to the chemical composition mass percentage of the niobium microalloyed wear-resistant steel described in this example. After smelting, the steel was cast into 150×150 mm continuous casting billets.

[0107] S2. Homogenization process:

[0108] The continuous casting billet in step S1 is subjected to a heating homogenization treatment, with a heating temperature of 1250° C. and a holding time of 1 hour.

[0109] S3, rolling process:

[0110] The continuous casting billet after the heating and homogenization treatment in step S2 is subjected to multiple rolling passes, with the starting rolling temperature being 1000-1050° C., the finishing rolling temperature being 760-800° C., and the deformation amount being 80%, to obtain a wear-resistant steel plate.

[0111] S4, cooling process:

[0112] The wear-resistant steel plate in step S3 is air-cooled to room temperature.

[0113] S5, quenching process:

[0114] The wear-resistant steel plate after air cooling in step S4 is heated to 1100° C. and kept at this temperature for 0.5 h. After the heating, the plate is quenched to room temperature, and the cooling rate is controlled at 100° C. / s.

[0115] S6, tempering process:

[0116] The wear-resistant steel plate quenched in step S5 is heated to 250° C. and kept at this temperature for 0.5 h, and then air-cooled to room temperature to obtain niobium microalloyed wear-resistant steel.

[0117] The microstructure of the niobium microalloyed wear-resistant steel prepared in this comparative example is tempered martensite, the hardness is ≥930 HV, and the tensile strength is ≥1160 MPa.

[0118] Comparative Example 3

[0119] The chemical composition of a niobium microalloyed wear-resistant steel is as follows: C: 0.77 wt.%, Nb: 0.03 wt.%, and the rest is Fe and inevitable impurities.

[0120] A method for preparing niobium microalloyed wear-resistant steel comprises the following steps:

[0121] S1. Smelting and casting process:

[0122] The raw materials were weighed, batched, and smelted according to the chemical composition mass percentage of the niobium microalloyed wear-resistant steel described in this example. After smelting, the steel was cast into 150×150 mm continuous casting billets.

[0123] S2. Homogenization process:

[0124] The continuous casting billet in step S1 is subjected to a heating homogenization treatment, with a heating temperature of 1250° C. and a holding time of 1 hour.

[0125] S3, rolling process:

[0126] The continuous casting billet after the heating and homogenization treatment in step S2 is subjected to multiple rolling passes, with the starting rolling temperature being 1000-1050° C., the finishing rolling temperature being 760-800° C., and the deformation amount being 80%, to obtain a wear-resistant steel plate.

[0127] S4, cooling process:

[0128] The wear-resistant steel plate in step S3 is air-cooled to room temperature.

[0129] S5, quenching process:

[0130] The wear-resistant steel plate after air cooling in step S4 is heated to 1100° C. and kept at this temperature for 0.5 h. After the heating, the plate is quenched to room temperature, and the cooling rate is controlled at 100° C. / s.

[0131] S6, tempering process:

[0132] The wear-resistant steel plate quenched in step S5 is heated to 250° C. and kept at this temperature for 0.5 h, and then air-cooled to room temperature to obtain niobium microalloyed wear-resistant steel.

[0133] The microstructure of the niobium microalloyed wear-resistant steel prepared in this comparative example is tempered martensite, the hardness is ≥910 HV, and the tensile strength is ≥1100 MPa.

[0134] Comparative Example 4

[0135] The chemical composition of a niobium microalloyed wear-resistant steel is as follows: C: 0.86 wt.%, Nb: 0.03 wt.%, and the rest is Fe and inevitable impurities.

[0136] A method for preparing niobium microalloyed wear-resistant steel comprises the following steps:

[0137] S1. Smelting and casting process:

[0138] The raw materials were weighed, mixed, and smelted according to the chemical composition mass percentage of the niobium microalloyed wear-resistant steel described in this embodiment. After smelting, the steel was cast into 150×150 mm continuous casting billets.

[0139] S2. Homogenization process:

[0140] The continuous casting billet in step S1 is subjected to heating homogenization treatment, with a heating temperature of 1250° C. and a holding time of 1 h, and the microstructure is austenite.

[0141] S3, rolling process:

[0142] The continuous casting billet after the heating and homogenization treatment in step S2 is subjected to multiple rolling passes, with the starting rolling temperature being 1050° C., the finishing rolling temperature being 800° C., and the deformation amount being 80%, to obtain a wear-resistant steel plate.

[0143] S4, cooling process:

[0144] The wear-resistant steel plate in step S3 is air-cooled to room temperature.

[0145] S5, quenching process:

[0146] The wear-resistant steel plate in step S4 is heated to 1100° C. and kept at this temperature for 0.5 h. After heating, it is quenched to room temperature, and the cooling rate is controlled at 100° C. / s.

[0147] S6, tempering process:

[0148] The wear-resistant steel plate quenched in step S5 was heated to 250° C. under a high pressure of 5 GPa in a six-sided top press, tempered and kept warm for 0.5 h, and then air-cooled to room temperature to obtain niobium microalloyed wear-resistant steel.

[0149] The microstructure of the niobium microalloyed wear-resistant steel prepared in this comparative example is tempered martensite and carbide particles, the hardness is ≥1030 HV, and the tensile strength is ≥1420 MPa.

[0150] Comparative Example 5

[0151] The chemical composition of a niobium microalloyed wear-resistant steel is as follows: C: 0.70 wt.%, Nb: 0.05 wt.%, and the rest is Fe and inevitable impurities.

[0152] A method for preparing niobium microalloyed wear-resistant steel comprises the following steps:

[0153] S1. Smelting and casting process:

[0154] The raw materials were weighed, mixed, and smelted according to the chemical composition mass percentage of the niobium microalloyed wear-resistant steel described in this embodiment. After smelting, the steel was cast into 150×150 mm continuous casting billets.

[0155] S2. Homogenization process:

[0156] The continuous casting billet in step S1 is subjected to heating homogenization treatment, with a heating temperature of 1250° C. and a holding time of 1 h, and the microstructure is austenite.

[0157] S3, rolling process:

[0158] The continuous casting billet after the heating and homogenization treatment in step S2 is subjected to multiple rolling passes, with the starting rolling temperature being 1050° C., the finishing rolling temperature being 800° C., and the deformation amount being 80%, to obtain a wear-resistant steel plate.

[0159] S4, cooling process:

[0160] The wear-resistant steel plate in step S3 is air-cooled to room temperature.

[0161] S5, quenching process:

[0162] The wear-resistant steel plate in step S4 is placed in a six-sided press and pressure is applied to all six sides at the same time. The applied pressure is 5 GPa, and it is heated to 1100°C in the six-sided press and kept warm for 0.5h. After the end, it is quenched to room temperature and the cooling rate is controlled at 100°C / s.

[0163] S6, tempering process:

[0164] The wear-resistant steel plate after quenching in step S5 is heated to 250° C. and tempered and kept at this temperature for 0.5 h. After tempering, the plate is air-cooled to room temperature to obtain niobium microalloyed wear-resistant steel.

[0165] The microstructure of the niobium microalloyed wear-resistant steel prepared in this comparative example is tempered martensite and carbide particles, the hardness is ≥980 HV, and the tensile strength is ≥1260 MPa.

[0166] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing niobium microalloyed high performance wear-resistant steel, characterized in that: include: (1) preparing the raw materials according to the chemical composition of niobium microalloyed high-performance wear-resistant steel, smelting the steel, and casting the steel into a billet; the niobium microalloyed high-performance wear-resistant steel comprises the following elements in percentage by weight: C: 0.70-0.90 wt.%, Nb: 0.01-0.05 wt.%, and the remainder being Fe and unavoidable impurities; (2) The ingot is subjected to homogenization treatment, rolling treatment, and cooling in sequence to obtain a wear-resistant steel plate; (3) Apply 3-5 GPa pressure to the six sides of the wear-resistant steel plate and heat it to a quenching temperature of 950-1150 ° C for 0.5-1h. After the quenching, quench it to room temperature. The cooling rate of quenching is above 50 ° C / s; (4) Applying a pressure of 3-5 GPa to the six sides of the quenched wear-resistant steel plate at the same time and heating it to a tempering temperature of 200-300°C for 0.5-1h, and then air-cooling it to room temperature to obtain niobium microalloyed high-performance wear-resistant steel.

2. The niobium microalloyed high-performance wear-resistant steel prepared by the method for preparing niobium microalloyed high-performance wear-resistant steel according to claim 1, characterized in that: The microstructure of the niobium microalloyed high-performance wear-resistant steel includes tempered martensite and carbide, and the carbide particle size is 1-3 μm.

3. The niobium microalloyed high performance wear-resistant steel according to claim 2, characterized in that: The niobium microalloyed high-performance wear-resistant steel has a hardness of ≥1150 HV and a tensile strength of ≥1550 MPa.

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