High-wear-resistance improved H13 steel and heat treatment process method thereof

Abstract

The invention belongs to the technical field of metal materials, and relates to high-wear-resistance improved H13 steel and a heat treatment process method thereof. The high-wear-resistance improved H13 steel is prepared from the following components in percentage by weight: 0.55 to 0.75 percent of C, 4.75 to 5.5 percent of Cr, 1.10 to 1.75 percent of Mo, 1.0 to 1.2 percent of V, 0.8 to 1.2 percent of Si, 0.2 to 0.5 percent of Mn, trace elements and the balance of Fe, and the trace element is one or a combination of more of 0.05 to 0.1 weight percent of Ni (nickel), 0.005 to 0.01 weight percent of Co (cobalt), 0.05 to 0.1 weight percent of Al (aluminum), 0.001 to 0.005 weight percent of B (boron), 0.005 to 0.008 weight percent of Zr (zirconium), 0.005 to 0.01 weight percent of Nb (niobium) and 0.005 to 0.01 weight percent of Ti (titanium). Through adjustment of steel elements and cooperation of a heat treatment process, the wear resistance of the H13 steel is greatly improved, and the service life of a finished product of the H13 steel is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials and relates to a highly wear-resistant improved H13 steel and a heat treatment process method thereof. Background Art

[0002] As a hot work die steel, H13 steel plays a crucial role in industrial production. It is widely used in the manufacture of hot work dies, such as forging dies, die-casting dies, and extrusion dies. These dies are primarily used in metal forming processes such as forging, die-casting, and extrusion. In these processes, the dies must withstand complex conditions of high temperature, high pressure, and high stress. The wear resistance of traditional H13 steel has certain limitations in these demanding applications and needs further improvement.

[0003] Despite extensive research and application efforts to improve the wear resistance of H13 steel, existing technologies still have some shortcomings. For example, the current wear resistance of H13 steel does not meet operating requirements. Furthermore, certain composition adjustments and heat treatment process optimizations increase production costs and have certain environmental impacts. Wear-resistant steel primarily improves its heat resistance and high-temperature wear resistance by increasing the alloying element content. However, excessive alloying element additions increase the steel's smelting cost. Furthermore, excessive alloying elements in the steel can lead to increased segregation during solidification, resulting in the formation of large-sized liquid carbides, which reduces mechanical properties such as wear resistance. Therefore, high-carbon and high-alloy steels require high-temperature diffusion treatment and high-proportion forging deformation to improve the morphology of carbides. This significantly increases steel cost, consumes significant energy, increases steel loss, and imposes a certain environmental burden. Addressing these issues through precise composition design and process optimization tailored to actual needs remains challenging.

[0004] Therefore, there is a need for a highly wear-resistant improved H13 steel and a heat treatment process method thereof to solve the above problems. Summary of the Invention

[0005] In view of the above technical problems, the present invention provides a highly wear-resistant improved H13 steel and a heat treatment process thereof. The present invention significantly improves the wear resistance of H13 steel and increases the yield of H13 steel by adjusting the steel elements and coordinating the heat treatment process.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions.

[0007] A highly wear-resistant improved H13 steel comprising the following components: C: 0.55 - 0.75 wt%, Cr: 4.75 - 5.5 wt%, Mo: 1.10 - 1.75 wt%, V: 1.0 - 1.2wt%, Si: 0.8 - 1.2 wt%, Mn: 0.2 - 0.5 wt%, trace elements, Fe balance.

[0008] Furthermore, the trace elements are one or more combinations of Ni: 0.05 - 0.1 wt%, Co: 0.005 - 0.01 wt%, Al: 0.05 -0.1 wt%, B: 0.001 - 0.005 wt%, Zr: 0.005- 0.008 wt%, Nb: 0.005 - 0.01 wt%, and Ti: 0.005-0.01 wt%.

[0009] A heat treatment process for improved H13 steel with high wear resistance, comprising the following steps: Step 1, weighing each component according to the ratio, adding trace elements, and smelting the modified H13 steel ingot containing trace elements by vacuum induction and vacuum consumable / gas-backed electroslag; Step 2: subjecting the modified H13 steel ingot prepared in step 1 to a high-temperature diffusion treatment at a temperature of 1100-1250° C. for a holding time of 10-30 hours to uniformize the element distribution and partially dissolve the liquid carbides into the matrix; Step 3: subjecting the improved H13 steel ingot prepared in step 2 to a high-temperature deformation and drawing treatment at a temperature of 950-1200° C. for a holding time of 30-240 min to refine the eutectic carbide; Step 4: rolling the improved H13 steel ingot produced in step 3 into steel bars of required size; Step 5: Spheroidizing annealing the steel rods in step 4 and then peeling or grinding them for later use; Step 6: Machining the improved H13 steel raw material in step 5 to produce parts, leaving a 0.2-0.5mm margin on one side; Step 7: performing austempering treatment on the parts of step 6; Step 8: Controlling the phase change rate and temperature-controlled cooling after austempering; Step 9: Tempering the modified H13 steel obtained in step 8; Step 10: fine grinding the tempered modified H13 steel parts to obtain highly wear-resistant modified H13 steel.

[0010] Furthermore, in step 1, vacuum induction and vacuum consumable / gas shielded electroslag smelting are performed, with a melting temperature of 1400-1500° C. and solidification within a short time.

[0011] Furthermore, in step 4, the size is φ5-200 mm.

[0012] Furthermore, in step 5, the preheating temperature of the spheroidizing annealing is 700-750°C, the preheating time is 2-3h, and then the steel is heated to 790-860°C and kept at this temperature for 6-7h. The steel is then cooled with the furnace to 700-740°C and kept at this temperature for 11-12h. The steel is then cooled to 650°C at a rate of 20°C / h, and then cooled with the furnace to 500-550°C and air-cooled.

[0013] Furthermore, in step 7, the austempering heat treatment can be performed in two ways. The first way is salt bath austempering. The modified H13 steel after spheroidizing annealing is placed in a furnace with gas protection function and isothermal salt bath quenching function, and first heated to 780-820°C at a rate of 8-10°C / min, and kept at this temperature for 30-40min to austenitize the steel. At the same time, some carbides of the components are dissolved, and then the sample is heated to 1000-1020°C at a rate of 5-8°C / min and kept warm for 30-40min. Then, the sample is heated to 1030-1080°C at a rate of 3-5°C / min and kept warm for 10-20min. After the insulation is completed, it is taken out of the furnace for quenching and quenched into a salt bath with a furnace temperature of 200-250°C for 2-4h. It is required to run from the heat treatment furnace to the salt bath furnace and fully immersed in the salt bath for less than 20 seconds to ensure that the parts can cool down less after heating and control the precipitation of carbides before quenching. The salt bath furnace should have a stirring function and the salt bath flow direction is required to flow from the bottom to the top of the material frame to form an effective flow to ensure that the parts can be cooled evenly and the salt furnace temperature is uniform. The second method is vacuum isothermal quenching. The modified H13 steel after spheroidizing annealing is placed in a vacuum gas quenching furnace. The furnace is first evacuated to 5×10 - 1 Pa-5×10 -2 Pa, the temperature is started to rise, first at a rate of 8-10℃ / min to 780-820℃, and kept at this temperature for 30-40min, then at a rate of 3-6℃ / min, the sample is heated to 1030-1080℃, austenitized and kept for 30-40min, then 2-12bar nitrogen is filled into the furnace, the fan is started for stirring, the surface of the improved H13 steel sample is quickly cooled to 180-220℃, and isothermal for 1-4h, then the inflation pressure and stirring speed are adjusted, and the workpiece is cooled to 40-50℃ in the range of 40-60min and taken out of the furnace.

[0014] Furthermore, in step 8, the phase transformation rate and temperature-controlled cooling after austempering are controlled by removing the component from the salt bath and placing it in a heat treatment furnace or insulated box with a heat-insulating function. The cooling rate of the steel is controlled so that the time required to cool from the quenching temperature to 40°C is 30-60 minutes. By controlling the cooling rate, the rate at which austenite in the steel transforms into martensite is controlled, thereby controlling the residual stress in the component.

[0015] Furthermore, in step 9, the tempering requirement is: after quenching, the steel should be cooled to below 40°C before tempering can be carried out. After quenching, the time interval between the first tempering should be within 5 hours. There is no strict time requirement between the second and third tempering treatments and the first tempering treatment. Tempering is carried out in a gas-shielded furnace or a vacuum furnace with a vacuum degree of 5×10 -1 -5×10 -2 Pa, heat to 450-600℃ at a rate of 6-10℃ / min, hold for 2-5h, cool to below 40℃ with air cooling at a pressure of 0.6bar-1.5bar. Cool in air during tempering in a gas-shielded furnace. Temper 2-3 times.

[0016] Compared with the prior art, the present invention has the following beneficial effects.

[0017] 1. In the existing H13 steel modification technology, by precisely adjusting the content of each element, its overall performance can be effectively improved, thus showing many significant advantages in fields such as mold manufacturing: On the one hand, a reasonable increase in carbon content improves the matrix hardness of H13 steel, which enhances the mold's ability to withstand high stresses during operation, reduces mold failure due to plastic deformation, and effectively extends the mold's service life. For example, in some large die-casting molds, appropriately increasing the carbon content reduces surface collapse and excessive wear under repeated high-temperature and high-pressure die-casting environments, allowing for the continuous and stable production of thousands of high-quality die-cast products. On the other hand, when the amount of chromium added is optimized, it forms an alloy matrix with elements such as iron, which can form a dense and uniform chromium oxide film on its surface. This oxide film has extremely strong oxidation resistance. During heat treatment and in the high-temperature environment when the mold is operating, it can effectively prevent further oxidation of the mold surface, ensuring that the mold's dimensional accuracy and surface roughness remain good after long-term use. This is particularly critical for the production of precision molds with extremely high dimensional accuracy requirements, such as electronic component molds, to ensure product accuracy and consistency. At the same time, the moderate increase in molybdenum content further enhances the toughness of H13 steel, making the mold less susceptible to brittle fracture under impact loads. When producing large automotive parts molds, H13 steel molds with added molybdenum can better withstand the impact of molten metal and mechanical collisions during mold opening and closing, reducing sudden fractures caused by localized stress concentration and improving production safety. Properly controlling the vanadium content, due to its grain refinement, makes the microstructure of H13 steel more uniform and dense, not only improving the material's strength but also further enhancing its wear resistance. In molds used to process high-hardness, high-strength materials, such as milling cutter molds used to process high-strength alloys, vanadium-added H13 steel effectively resists the intense friction and impact of the processed material, extending the life of the mold cutting edge and ensuring sustained machining precision. Furthermore, the addition of trace elements like boron, aluminum, cobalt, and titanium has an unexpected synergistic effect. Boron improves the hardenability of H13 steel. During the quenching process of large molds, it ensures uniform hardening throughout the mold core, avoiding uneven hardness gradients. This is crucial for improving the quality of thick and large molds. Furthermore, boron promotes bainite formation, shortening the incubation period and increasing the amount of bainite formed. The trace addition of aluminum helps form a high-performance alumina film on the mold surface, further enhancing its corrosion resistance and effectively extending its service life, especially in humid, acidic, or alkaline working environments. The addition of cobalt enhances the high-temperature hardness of the H13 steel matrix, ensuring that the mold retains its hardness even under high-temperature conditions. This can significantly improve production efficiency for molds operating in high-temperature environments, such as hot extrusion dies. The addition of titanium forms stable carbonitrides with carbon, nitrogen and other elements, which are dispersed in the H13 steel matrix, playing a good precipitation strengthening role, further refining the grains, and taking the comprehensive performance of the mold to a higher level. In summary, the technology of the present invention accurately controls the content of elements such as carbon (C), chromium (Cr), molybdenum (Mo), and vanadium (V) by appropriately increasing the content of each element, thereby improving the hardenability and hardness of the steel and enhancing the wear resistance. These alloying elements can promote the formation of fine and evenly distributed carbides, which can effectively prevent the deformation of the matrix after heat treatment and improve the wear resistance of the steel; and by adding trace elements such as boron (B), aluminum (Al), cobalt (Co), and titanium (Ti), the chemical composition of H13 steel is optimized; these trace elements refine the grains, improve the strength and toughness of the steel, make the carbides finer and more evenly distributed, thereby significantly improving the hardness and wear resistance of the steel. The present invention comprehensively optimizes H13 steel in multiple aspects, including hardness, toughness, oxidation resistance, wear resistance, corrosion resistance, and high-temperature performance, making it a high-quality material that meets the needs of high-end mold manufacturing. This has brought significant benefits in improving mold production efficiency, reducing production costs, and ensuring product quality stability. In actual applications, the wear resistance of the improved H13 steel is improved by approximately 30% to 60% compared to traditional H13 steel.

[0018] 2. Improved H13 steel boasts increased hardness, enhanced wear resistance, and improved plasticity. This is due to the optimized microstructure formed during austempering, which imparts greater stability and deformation resistance under high stress. Austempering results in a more uniform metallographic structure in the improved H13 steel, significantly improving carbide morphology, resulting in smaller and more evenly distributed carbides. This not only enhances the material's microstructural stability but also improves its plasticity, toughness, and resistance to friction and wear.

[0019] 3. Compared with the traditional quenching process, the austempering process of the present invention accelerates the cooling rate in the high temperature stage and controls the cooling rate in the low temperature stage, so that the thermal stress is greatly released during the holding period, which significantly reduces the quenching stress and reduces the risk of workpiece deformation and cracking.

[0020] 4. Expanded Application Areas: The improved H13 steel significantly enhances its overall performance, expanding its application scope. It can meet higher standards in tool and die manufacturing, which requires high wear resistance, such as in aerospace, automotive manufacturing, and precision forging. In summary, this invention significantly improves the wear resistance and overall performance of H13 steel through chemical composition adjustment and heat treatment process optimization, reduces production costs, and has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The microstructures of the H13 steel of Comparative Example 1 and the improved H13 steel of Example 1 after quenching (a is Comparative Example 1, b is Example 1).

[0022] Figure 2The microstructures of the H13 steel of Comparative Example 1 and the improved H13 steel of Example 1 after quenching and tempering (a is Comparative Example 1, b is Example 1). DETAILED DESCRIPTION

[0023] The technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0024] A highly wear-resistant improved H13 steel comprising the following components: C: 0.55 - 0.75 wt%, Cr: 4.75 - 5.5 wt%, Mo: 1.10 - 1.75 wt%, V: 1.0 - 1.2wt%, Si: 0.8 - 1.2 wt%, Mn: 0.2 - 0.5 wt%, trace elements, Fe balance.

[0025] Furthermore, the trace elements are one or more combinations of Ni: 0.05 - 0.1 wt%, Co: 0.005 - 0.01 wt%, Al: 0.05 -0.1 wt%, B: 0.001 - 0.005 wt%, Zr: 0.005- 0.008 wt%, Nb: 0.005 - 0.01 wt%, and Ti: 0.005-0.01 wt%.

[0026] A heat treatment process for improved H13 steel with high wear resistance, comprising the following steps: Step 1: Weigh each component according to the proportion, add trace elements, and use vacuum induction and vacuum consumable / gas-backed electroslag to smelt the modified H13 steel ingot containing trace elements at a melting temperature of 1400-1500°C and solidify in a short time; Step 2: subjecting the modified H13 steel ingot prepared in step 1 to a high-temperature diffusion treatment at a temperature of 1100-1250° C. for a holding time of 10-30 hours to uniformize the element distribution and partially dissolve the liquid carbides into the matrix; Step 3: subjecting the improved H13 steel ingot prepared in step 2 to a high-temperature deformation and drawing treatment at a temperature of 950-1200° C. for a holding time of 30-240 min to refine the eutectic carbide; Step 4: rolling the improved H13 steel ingot produced in step 3 into steel bars of required size, with a size of φ5-200mm; Step 5, spheroidizing annealing the steel bar in step 4 and then peeling or grinding it for standby use; the preheating temperature of spheroidizing annealing is 700-750℃, the preheating time is 2-3h, then heating to 790-860℃, holding time is 6-7h, then cooling with the furnace to 700-740℃, holding time is 11-12h, then cooling to 650℃ at a rate of 20℃ / h, then cooling with the furnace to 500-550℃ and air cooling; Step 6: Machining the improved H13 steel raw material in step 5 to produce parts, leaving a 0.2-0.5mm margin on one side; Step 7, perform austempering treatment on the parts of step 6; austempering heat treatment can be performed in two ways. The first way is salt bath austempering. The improved H13 steel after spheroidizing annealing is placed in a furnace with gas protection function and isothermal salt bath quenching function. The temperature is first raised to 780-820°C at a rate of 8-10°C / min, and kept at this temperature for 30-40min to austenitize the steel. At the same time, some carbides of the components are dissolved. Then, the sample is heated to 1000-1020°C at a rate of 5-8°C / min and kept warm for 30-40min. Then, the sample is heated to 1030-1080°C at a rate of 3-5°C / min and kept warm for 10-20min. After the insulation is completed, it is taken out of the furnace for quenching and quenched into a salt bath with a furnace temperature of 200-250°C for 2-4h. It is required to run from the heat treatment furnace to the salt bath furnace and fully immersed in the salt bath for less than 20 seconds to ensure that the parts can cool down less after heating and control the precipitation of carbides before quenching. The salt bath furnace should have a stirring function and the salt bath flow direction is required to flow from the bottom to the top of the material frame to form an effective flow to ensure that the parts can be cooled evenly and the salt furnace temperature is uniform. The second method is vacuum isothermal quenching. The modified H13 steel after spheroidizing annealing is placed in a vacuum gas quenching furnace. The furnace is first evacuated to 5×10 -1 Pa-5×10 -2 After the sample reaches 300-400°C, the temperature is raised to 780-820°C at a rate of 8-10°C / min, and the sample is kept at this temperature for 30-40 minutes. Then, the sample is heated to 1030-1080°C at a rate of 3-6°C / min, austenitized and kept for 30-40 minutes. Then, 2-12 bar nitrogen is filled into the furnace, and the fan is started for stirring. The surface of the modified H13 steel sample is quickly cooled to 180-220°C, and the temperature is kept isothermal for 1-4 hours. Then, the charging pressure and stirring speed are adjusted, and the workpiece is cooled to 40-50°C in the range of 40-60 minutes and then taken out of the furnace. Step 8: After austempering, control the phase transformation rate and temperature-controlled cooling. This involves removing the component from the salt bath and placing it in a heat treatment furnace or insulated box with insulation function. The cooling rate of the steel is controlled so that the time required to cool from the quenching temperature to 40°C is 30-60 minutes. By controlling the cooling rate, the rate at which austenite in the steel transforms into martensite is controlled, and the residual stress in the component is controlled. Step 9: Temper the modified H13 steel from step 8. Tempering requirements: After quenching, the steel must be cooled to below 40°C before tempering can be performed. After quenching, the time interval between the first tempering should be within 5 hours. There is no strict time requirement between the second and third tempering treatments and the first tempering treatment. Tempering is performed in a gas-shielded furnace or a vacuum furnace with a vacuum degree of 5×10 -1 -5×10 -2 Pa, heat to 450-600℃ at a rate of 6-10℃ / min, keep warm for 2-5h, cool to below 40℃ with air cooling pressure of 0.6bar-1.5bar. Cool in air during tempering in gas shielded furnace. Tempering times are 2-3 times; Step 10: performing fine grinding on the tempered modified H13 steel parts to obtain highly wear-resistant modified H13 steel parts.

[0027] Example 1.

[0028] Step 1, modifying H13 steel, the element composition is as follows: C: 0.55wt%, Cr: 4.9wt%, Mo: 1.3wt%, V: 1.0wt%, Si: 0.9wt%, Mn: 0.4wt%, Ni: 0.05wt%, Co: 0.005wt%, Al: 0.05wt%, B: 0.001wt%, Zr: 0.005wt%, Nb: 0.005wt%, Ti: 0.005wt%, Fe balance; using vacuum induction and vacuum consumable smelting, the melting temperature is 1500℃, and solidification is carried out in a short time; Step 2: subjecting the steel ingot to a high-temperature diffusion treatment at 1200°C for 10 hours to uniformly distribute the elements and partially dissolve the liquid carbides into the matrix; Step 3: The steel ingot is subjected to high-temperature deformation and drawing treatment at a temperature of 1150° C. for a holding time of 120 min to refine the eutectic carbide; Step 4: rolling the ingot into a steel bar with a size of φ20 mm; Step 5: The preheating temperature of spheroidizing annealing is 730°C, the preheating time is 3 hours, then heated to 800°C, the holding time is 7 hours, then cooled to 725°C with the furnace, the holding time is 12 hours, then cooled to 650°C at a rate of 20°C / h, then cooled to 550°C with the furnace and air-cooled; Step 6: Machining the improved H13 steel raw material to produce parts, leaving a 0.2 margin on one side; Step 7, the processed parts made of improved H13 steel are subjected to salt bath austempering, and the improved H13 steel after spheroidizing annealing is placed in a furnace with gas protection function and isothermal salt bath quenching function, first heated to 780℃ at a rate of 8-10℃ / min, and kept at this temperature for 30min to austenitize the steel, while some carbides are dissolved, and then the sample is heated to 1000℃ at a rate of 5℃ / min and kept warm for 30min, and then heated to 1040℃ at a rate of 5℃ / min and kept warm for 20min. After the insulation is completed, the parts are taken out of the furnace for quenching, the salt bath furnace temperature is 240℃, and the insulation time is 2-4h. It is required to run from the heat treatment furnace to the salt bath furnace and be completely immersed in the salt bath for 10S. The salt bath has a stirring function, and the salt bath flows from the bottom to the top of the material frame to form an effective flow, ensuring that the parts can be evenly cooled and the salt furnace temperature is uniform. Step 8: After austempering, control the phase transformation rate and temperature-controlled cooling. Remove the component from the salt bath and place it in a heat treatment furnace or an insulation box with a heat preservation function. Control the cooling rate of the steel so that it takes 40 minutes to cool from the quenching temperature to 40°C. By controlling the cooling rate, the rate at which austenite in the steel transforms into martensite is controlled, and the residual stress in the component is controlled. Step 9: After quenching, cool to below 40°C before tempering. After quenching, the first tempering should be carried out within 5 hours. There is no strict time requirement between the second and third tempering treatments and the first tempering treatment. Tempering is carried out in a gas-shielded furnace, heating to 550°C at a rate of 6-10°C / min, keeping the temperature for 2-5 hours, and then cooling in air to below 40°C before the second tempering. A total of 2 temperings are carried out; Step 10: performing fine grinding on the tempered modified H13 steel part to obtain the modified H13 steel part.

[0029] A Vickers hardness tester was used to measure the modified H13 steel after austempering and tempering, revealing a Vickers hardness of 685 HV. Using a reciprocating friction and wear tester, under a pressure of 1000 N, a displacement speed of 10 mm / min, and a slip distance of 6 mm, the friction and wear weight loss was 3.72 mg. The tensile strength was 1411 MPa, the yield strength was 1010 MPa, and the elongation was 11.29%.

[0030] Example 2.

[0031] Step 1, modifying H13 steel, the element composition is as follows: C: 0.75wt%, Cr: 4.9wt%, Mo: 1.3wt%, V: 1.2wt%, Si: 0.9wt%, Mn: 0.4wt%, Ni: 0.05wt%, Co: 0.005wt%, Al: 0.05wt%, B: 0.001wt%, Zr: 0.005wt%, Nb: 0.005wt%, Ti: 0.005wt%, Fe balance; using vacuum induction and gas shielded electroslag smelting, the melting temperature is 1500℃, and solidification is carried out in a short time; Step 2: subjecting the steel ingot to a high-temperature diffusion treatment at 1210°C for 12 hours to uniformly distribute the elements and partially dissolve the liquid carbides into the matrix; Step 3: The steel ingot is subjected to high temperature deformation and drawing treatment at a temperature of 1140° C. for a holding time of 200 min to refine the eutectic carbide; Step 4: rolling the ingot into a steel bar with a size of φ50 mm; Step 5: The preheating temperature of spheroidizing annealing is 720°C, the preheating time is 2h, then heated to 800°C, the holding time is 6h, then cooled to 725°C with the furnace, the holding time is 11h, then cooled to 650°C at a rate of 20°C / h, then cooled to 550°C with the furnace and air-cooled; Step 6: Machining the improved H13 steel raw material to produce parts, leaving a 0.3 margin on one side; Step 7, the processed parts made of improved H13 steel are subjected to salt bath austempering, and the improved H13 steel after spheroidizing annealing is placed in a furnace with gas protection function and isothermal salt bath quenching function, first heated to 800 ° C at a rate of 9 ° C / min, and kept at this temperature for 30 minutes to austenitize the steel, while some carbides are dissolved, and then the sample is heated to 1010 ° C at a rate of 5 ° C / min, and kept warm for 30 minutes, and then heated to 1050 ° C at a rate of 5 ° C / min, and kept warm for 20 minutes. After the insulation is completed, the sample is taken out of the furnace for quenching, the salt bath furnace temperature is 220 ° C, and the insulation time is 3 hours. It is required to run from the heat treatment furnace to the salt bath furnace and be completely immersed in the salt bath for 15 seconds. The salt bath has a stirring function, and the salt bath flows from the bottom to the top of the material frame to form an effective flow, ensuring that the parts can be evenly cooled and the salt furnace temperature is uniform. Step 8: After austempering, control the phase transformation rate and temperature-controlled cooling. Remove the component from the salt bath and place it in a heat treatment furnace or an insulation box with a heat preservation function. Control the cooling rate of the steel so that the time required to cool from the quenching temperature to 40°C is 35 minutes. By controlling the cooling rate, the rate at which austenite in the steel transforms into martensite is controlled, and the residual stress in the component is controlled. Step 9: After quenching, the steel is cooled to below 40°C before tempering. After quenching, the time interval for the first tempering is within 5 hours. There is no strict time requirement between the second and third tempering treatments and the first tempering treatment. Tempering is carried out in a gas-protected furnace, heating to 550°C at a rate of 8°C / min, keeping the temperature for 2.5 hours, and then cooling in air to below 40°C, and then tempering for the second time. A total of 2 temperings are carried out. Step 10: performing fine grinding on the tempered modified H13 steel part to obtain the modified H13 steel part.

[0032] A Vickers hardness tester was used to measure the modified H13 steel after austempering and tempering, revealing a Vickers hardness of 693 HV. Using a reciprocating friction and wear tester, under a pressure of 1000 N, a displacement speed of 10 mm / min, and a slip distance of 6 mm, the friction and wear weight loss was 1.74 mg. The tensile strength was 1875 MPa, the yield strength was 1411 MPa, and the elongation was 13.2%.

[0033] Example 3.

[0034] Step 1, modifying H13 steel, the element composition is as follows: C: 0.65wt%, Cr: 4.9wt%, Mo: 1.3wt%, V: 1.2wt%, Si: 0.9wt%, Mn: 0.4wt%, Ni: 0.1wt%, Co: 0.01wt%, Al: 0.1wt%, B: 0.005wt%, Zr: 0.005wt%, Nb: 0.005wt%, Ti: 0.005wt%, Fe balance; using vacuum induction and vacuum consumable smelting, the melting temperature is 1500℃, and solidification is in a short time; Step 2: subjecting the steel ingot to a high-temperature diffusion treatment at 1230°C for 8 hours to uniformly distribute the elements and partially dissolve the liquid carbides into the matrix; Step 3: The steel ingot is subjected to high-temperature deformation and drawing treatment at a temperature of 1130° C. for a holding time of 240 min to refine the eutectic carbide; Step 4: rolling the ingot into a steel bar with a size of φ20 mm; Step 5: The preheating temperature for spheroidizing annealing is 750°C, the preheating time is 2 hours, then heated to 820°C, the holding time is 6 hours, then cooled to 720°C with the furnace, the holding time is 9 hours, then cooled to 650°C at a rate of 20°C / h, then cooled to 550°C with the furnace and air-cooled; Step 6: Machining the improved H13 steel raw material to produce parts, leaving a 0.3 margin on one side; Step 7, the processed parts made of improved H13 steel are subjected to salt bath austempering, and the improved H13 steel after spheroidizing annealing is placed in a furnace with gas protection function and isothermal salt bath quenching function, first heated to 800 ° C at a rate of 9 ° C / min, and kept at this temperature for 30 minutes to austenitize the steel, while some carbides are dissolved, and then the sample is heated to 1010 ° C at a rate of 5 ° C / min, and kept warm for 30 minutes, and then heated to 1050 ° C at a rate of 5 ° C / min, and kept warm for 20 minutes. After the insulation is completed, the sample is taken out of the furnace for quenching, the salt bath furnace temperature is 220 ° C, and the insulation time is 3 hours. It is required to run from the heat treatment furnace to the salt bath furnace and be completely immersed in the salt bath for 15 seconds. The salt bath has a stirring function, and the salt bath flows from the bottom to the top of the material frame to form an effective flow, ensuring that the parts can be evenly cooled and the salt furnace temperature is uniform. Step 8: After austempering, control the phase transformation rate and temperature-controlled cooling. Remove the component from the salt bath and place it in a heat treatment furnace or insulated box with insulation function. Control the cooling rate of the steel so that it takes 35 minutes to cool from the quenching temperature to 40°C. By controlling the cooling rate, the rate at which austenite in the steel transforms into martensite is controlled, and the residual stress in the component is controlled. Step 9: After quenching, the steel is cooled to below 40°C before tempering. After quenching, the time interval for the first tempering is within 5 hours. There is no strict time requirement between the second and third tempering treatments and the first tempering treatment. Tempering is carried out in a gas-protected furnace, heating to 550°C at a rate of 8°C / min, keeping the temperature for 2.5 hours, and then cooling in air to below 40°C, and then tempering for the second time. A total of 2 temperings are carried out. Step 10: performing fine grinding on the tempered modified H13 steel part to obtain the modified H13 steel part.

[0035] The Vickers hardness of the modified H13 steel after austempering and tempering was 640.3 HV using a Vickers hardness tester. Using a reciprocating friction and wear tester, under a pressure of 1000 N, a displacement speed of 10 mm / min, and a slip distance of 6 mm, the friction and wear weight loss was 2.61 mg. The tensile strength was 1850 MPa, the yield strength was 1450 MPa, and the elongation was 15.2%.

[0036] Comparative Example 1.

[0037] Step 1: H13 steel, elemental composition is as follows: C: 0.4 wt%, Cr: 5.0 wt%, Mo: 1.45 wt%, V: 1.0 wt%, Si: 0.9 wt%, Mn: 0.4 wt%, Fe balance; vacuum induction and gas shielded electroslag smelting is adopted, the melting temperature is 1500 ° C, and solidification is carried out in a short time; Step 2: subjecting the steel ingot to a high-temperature diffusion treatment at 1200°C for 8 hours to uniformly distribute the elements and partially dissolve the liquid carbides into the matrix; Step 3: The steel ingot is subjected to high-temperature deformation and drawing treatment at a temperature of 1130° C. for a holding time of 240 min to refine the eutectic carbide; Step 4: rolling the ingot into a steel bar with a size of φ80 mm; Step 5: The preheating temperature for spheroidizing annealing is 750°C, the preheating time is 2 hours, then heated to 820°C, the holding time is 6 hours, then cooled to 720°C with the furnace, the holding time is 9 hours, then cooled to 650°C at a rate of 20°C / h, then cooled to 550°C with the furnace and air-cooled; Step 6: Machining the H13 steel raw material to produce parts, leaving a 0.3 margin on one side; Step 7, the processed H13 steel parts are subjected to salt bath austempering, and the H13 steel after spheroidizing annealing is placed in a furnace with gas protection function and isothermal salt bath quenching function, first heated to 800 ℃ at a rate of 9 ℃ / min, and kept at this temperature for 30 min to austenitize the steel, while some carbides are dissolved, and then the sample is heated to 1010 ℃ at a rate of 5 ℃ / min, and kept warm for 30 min, and then heated to 1050 ℃ at a rate of 5 ℃ / min, and kept warm for 20 min. After the insulation is completed, the parts are taken out of the furnace for quenching, the salt bath furnace temperature is 220 ℃, and the insulation time is 3 h. The time from the heat treatment furnace to the salt bath furnace and completely immersed in the salt bath is 15 s. The salt bath has a stirring function, and the salt bath flows from the bottom to the top of the material frame to form an effective flow, ensuring that the parts can be evenly cooled and the temperature of the salt furnace is uniform. Step 8: After austempering, control the phase transformation rate and temperature-controlled cooling. Remove the component from the salt bath and place it in a heat treatment furnace or an insulation box with a heat preservation function. Control the cooling rate of the steel so that the time required to cool from the quenching temperature to 40°C is 35 minutes. By controlling the cooling rate, the rate at which austenite in the steel transforms into martensite is controlled, and the residual stress in the component is controlled. Step 5: After quenching, the steel is cooled to below 40°C before tempering. After quenching, the time interval for the first tempering is within 5 hours. There is no strict time requirement between the second and third tempering treatments and the first tempering treatment. Tempering is carried out in a gas-protected furnace, heating to 550°C at a rate of 8°C / min, keeping the temperature for 2.5 hours, and then cooling in air to below 40°C, and then tempering for the second time. A total of 2 temperings are carried out. Step 6: Perform fine grinding on the tempered H13 steel part to obtain the H13 steel part.

[0038] A Vickers hardness tester was used to measure the Vickers hardness of H13 steel after austempering and tempering to be 615.5 HV. Using a reciprocating friction and wear tester, under a pressure of 1000 N, a displacement speed of 10 mm / min, and a slip distance of 6 mm, the friction and wear weight loss was 4.8 mg. The tensile strength was 2045 MPa, the yield strength was 1693 MPa, and the elongation was 9.54%.

[0039] Figure 1 (a) shows the microstructure of H13 steel after quenching in Comparative Example 1. The grain size in the steel is relatively large, and the bainite structure formed in the steel is long and has no rod-shaped carbides. Figure 2 As shown in (a), after adjusting the main elements and adding trace elements, the microstructure of the improved H13 steel of Example 1 after quenching has a large amount of undissolved granular carbides distributed inside the grains and at the grain boundaries. The carbides are small in size, smooth and granular, with a size of about 2-5 μm. Compared with the H13 steel of Comparative Example 1, the grains are significantly refined. After quenching, obvious grain boundary characteristics are observed, and rod-shaped carbides are precipitated at the grain boundaries.

[0040] H13 steel without adjusting basic composition and adding trace elements precipitates granular carbides after tempering, and the bainite characteristics formed are not obvious after tempering. Figure 2 (a) As shown. After tempering, H13 steel with adjusted matrix composition and added trace elements forms more bainite structure compared to the structure without adding trace elements. More fine carbides are precipitated on the matrix and the arrangement is more regular, as shown in the attached figure. Figure 2 (b)

[0041] The hardness of the H13 steel in Comparative Example 1 was 615 HV, while the improved H13 steel in Example 1 reached a maximum hardness of 693 HV. In wear resistance testing, under the same stress and time conditions, the weight loss of the H13 steel in Comparative Example 1 was 4.80 mg, while the weight loss of the improved H13 steel in Example 1 was 1.74 mg. This demonstrates that the improved H13 steel significantly improves its hardness and wear resistance.

Claims

1. A high wear-resistant improved H13 steel, characterized in that: It consists of the following components: C： 0.55 - 0.75 wt%, Cr: 4.75 - 5.5 wt%, Mo: 1.10 - 1.75 wt%, V: 1.0 - 1.2 wt%, Si: 0.8 - 1.2 wt%, Mn: 0.2 - 0.5 wt%, trace elements, Fe balance.

2. The high wear resistance improved H13 steel according to claim 1, characterized in that The trace elements are one or more combinations of Ni: 0.05-0.1 wt%, Co: 0.005-0.01 wt%, Al: 0.05-0.1 wt%, B: 0.001-0.005 wt%, Zr: 0.005-0.008 wt%, Nb: 0.005-0.01 wt%, and Ti: 0.005-0.01 wt%.

3. A heat treatment process for high wear resistance improved H13 steel, characterized in that: The following steps are involved: Step 1, weighing each component according to the ratio, adding trace elements, and smelting the modified H13 steel ingot containing trace elements by vacuum induction and vacuum consumable / gas-backed electroslag; Step 2: subjecting the modified H13 steel ingot prepared in step 1 to a high-temperature diffusion treatment at a temperature of 1100-1250° C. for a holding time of 10-30 hours to uniformize the element distribution and partially dissolve the liquid carbides into the matrix; Step 3: subjecting the improved H13 steel ingot prepared in step 2 to a high-temperature deformation and drawing treatment at a temperature of 950-1200° C. for a holding time of 30-240 min to refine the eutectic carbide; Step 4: rolling the improved H13 steel ingot produced in step 3 into steel bars of required size; Step 5: Spheroidizing annealing the steel rods in step 4 and then peeling or grinding them for later use; Step 6: Machining the improved H13 steel raw material in step 5 to produce parts, leaving a 0.2-0.5mm margin on one side; Step 7: performing austempering treatment on the parts of step 6; Step 8: Controlling the phase change rate and temperature-controlled cooling after austempering; Step 9: Tempering the modified H13 steel obtained in step 8; Step 10: fine grinding the tempered modified H13 steel parts to obtain highly wear-resistant modified H13 steel.

4. The heat treatment process for high wear resistance improved H13 steel according to claim 3, characterized in that: In the step 1, the melting temperature of vacuum induction and vacuum consumable / gas shielded electroslag smelting is 1400-1500° C., and solidification occurs in a short time.

5. The heat treatment process for improved H13 steel with high wear resistance according to claim 3, characterized in that: In step 4, the size is φ5-200mm.

6. The heat treatment process for improved H13 steel with high wear resistance according to claim 3, characterized in that: In the step 5, the preheating temperature of the spheroidizing annealing is 700-750°C, the preheating time is 2-3h, then the steel is heated to 790-860°C, the holding time is 6-7h, then the steel is cooled with the furnace to 700-740°C, the holding time is 11-12h, then cooled to 650°C at a rate of 20°C / h, then cooled with the furnace to 500-550°C and air-cooled.

7. The heat treatment process for high wear resistance improved H13 steel according to claim 3, characterized in that: In the step 7, the isothermal quenching heat treatment is carried out in two ways. The first way is salt bath isothermal quenching. The improved H13 steel after spheroidizing annealing is placed in a furnace with gas protection function and isothermal salt bath quenching function. The temperature is first raised to 780-820°C at a rate of 8-10°C / min and kept at this temperature for 30-40min to austenitize the steel and dissolve some carbides. Then, the sample is heated to 1000-1020°C at a rate of 5-8°C / min and kept warm for 30-40min. Then, the sample is heated to 1030-1080°C at a rate of 3-5°C / min and kept warm for 10- 20min, after the end of the heat preservation, it is taken out of the furnace for quenching and quenched into a salt bath with a furnace temperature of 200-250℃. The heat preservation time is 2-4h. It is required to run from the heat treatment furnace to the salt bath furnace and be completely immersed in the salt bath for less than 20S to ensure that the heated parts can cool down less and control the precipitation of carbides before quenching. The salt bath furnace should have a stirring function. The salt bath flow direction is required to flow from the bottom to the top of the material frame to form an effective flow to ensure that the parts can be evenly cooled and the salt furnace temperature is uniform. The second method is vacuum isothermal quenching. The improved H13 steel after spheroidizing annealing is placed in a vacuum gas quenching furnace. The furnace is first evacuated to 5×10 -1 Pa-5×10 -2 Pa, the temperature is started to rise, first at a rate of 8-10℃ / min to 780-820℃, and kept at this temperature for 30-40min, then at a rate of 3-6℃ / min, the sample is heated to 1030-1080℃, austenitized and kept for 30-40min, then 2-12bar nitrogen is filled into the furnace, the fan is started for stirring, the surface of the improved H13 steel sample is quickly cooled to 180-220℃, and isothermal for 1-4h, then the inflation pressure and stirring speed are adjusted, and the workpiece is cooled to 40-50℃ in the range of 40-60min and taken out of the furnace.

8. The heat treatment process for improved H13 steel with high wear resistance according to claim 3, characterized in that: In step 8, the phase transformation rate is controlled and the temperature-controlled cooling is performed after austempering. The component is removed from the salt bath and then placed in a heat treatment furnace or an insulation box with an insulation function. The cooling rate of the steel is controlled so that the time required to cool from the quenching temperature to 40°C is 30-60 minutes. By controlling the cooling rate, the rate at which austenite in the steel transforms into martensite is controlled, and the residual stress in the component is controlled.

9. The heat treatment process for improved H13 steel with high wear resistance according to claim 3, characterized in that: In step 9, the tempering requirements are as follows: after quenching, the tempering treatment can be carried out only after cooling to below 40°C. After quenching, the time interval for the first tempering treatment is within 5 hours; there is no strict time requirement between the second and third tempering treatments and the first tempering treatment; tempering is carried out in a gas-shielded furnace or a vacuum furnace with a vacuum degree of 5×10 -1 -5×10 -2 Pa, heat to 450-600℃ at a rate of 6-10℃ / min, keep warm for 2-5h, air cooling pressure is 0.6bar-1.5bar, cool to below 40℃, cool in air during tempering in gas shielded furnace, tempering times are 2-3 times.

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