High-wear-resistance hot rolled steel ball and surface strengthening heat treatment process thereof

Abstract

The invention belongs to the technical field of steel ball machining, and discloses a high-wear-resistance hot-rolled steel ball and a surface strengthening heat treatment process thereof.The high-wear-resistance hot-rolled steel ball comprises a steel ball body, the steel ball body comprises a surface layer, a transition layer and a core layer, the surface of the core layer is covered with the transition layer, and the surface of the transition layer is covered with the surface layer. Through a reasonable heat treatment process, the uniformity and strength of the steel ball are enhanced, and good support is provided for a surface layer; the surface layer is made of high-chromium alloy steel Cr15, and the surface hardness and wear resistance of the steel ball are remarkably improved due to the high chromium content of the high-chromium alloy steel Cr15. In addition, the surface of the steel ball is further strengthened through carburizing and nitriding treatment, a hard carbonization layer and a hard nitriding layer are formed, and abrasion in the using process is effectively resisted. Through the combined action of the measures, the steel ball can still keep long service life under the severe working condition, and the replacement frequency and the use cost are remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of steel ball processing, and in particular relates to a high-wear-resistant hot-rolled steel ball and a surface strengthening heat treatment process thereof. Background Art

[0002] Steel balls can be divided into grinding steel balls, forging steel balls, casting steel balls, etc. according to the production and processing technology; they can be divided into bearing steel balls, stainless steel balls, carbon steel balls, alloy balls, etc. according to the processing materials. Among them, bearing steel balls are important basic parts of the industry, and alloy steel balls are a kind of spherical iron alloy wear-resistant body produced by forging, spinning, rolling and casting with carbon, chromium, manganese, molybdenum and other metal elements as the main additions. They are widely used in the crushing industry and the bearing industry. Traditional steel balls are limited by the material and will wear out after a period of use, which will affect the surface quality of the steel balls and increase the cost of use. Improvement is urgently needed.

[0003] When performing surface strengthening heat treatment on steel balls, insufficient hardness and uneven hardness often occur, which are mainly caused by factors such as insufficient quenching cooling speed, surface decarburization, insufficient hardenability of steel, excessive residual austenite after quenching, insufficient tempering, and uneven furnace temperature during heating. Insufficient heating temperature or insulation time are the main reasons for uneven heating. Uneven cooling may be caused by insufficient stirring of the quenching medium, bubbles attached to the surface of the workpiece, contamination of the quenching medium, or insufficient stirring of the quenching medium. At the same time, quenching cracks may also occur. The main reason is that the cracks formed by internal stress during the cooling process are called quenching cracks, which have a great impact on the quality of the steel balls and need to be improved urgently. Summary of the invention

[0004] The object of the present invention is to provide a highly wear-resistant hot-rolled steel ball and a surface strengthening heat treatment process thereof to solve the problems raised in the above-mentioned background technology.

[0005] In order to achieve the above object, the present invention provides the following technical solution: a highly wear-resistant hot-rolled steel ball, comprising a steel ball body, the steel ball body comprising a surface layer, a transition layer and a core layer, the surface of the core layer is covered with the transition layer, and the surface of the transition layer is covered with the surface layer; The surface strengthening heat treatment process includes the following steps: S1: preliminary processing; S2: Hot rolling treatment: S3: layered heat treatment; S4: surface pretreatment; S5: Carburizing treatment: S6: nitriding treatment; S7: Shot Peening: S8: Quality inspection; The surface heat treatment includes surface cleaning and surface drying, the carburizing treatment includes material preheating, material penetration and material cooling, the nitriding treatment includes nitriding pre-treatment, material nitriding and final cooling, the shot peening treatment includes surface shot peening and final cleaning, and the quality inspection includes hardness testing, microstructure inspection and wear testing.

[0006] As a further technical solution of the present invention, the core layer is made of medium carbon steel C45, and its chemical composition is C: 0.42-0.50%, Mn: 0.50-0.80%, Si: ≤0.40%, P: ≤0.035%, S: ≤0.035%; the transition layer is made of low alloy high strength steel 16MnCr5, and its chemical composition is C: 0.14-0.19%, Mn: 1.00-1.30%, Cr: 0.70-0.90%, Si: ≤0.40%, P: ≤0.035%, S: ≤0.035%; the surface layer is made of high chromium alloy steel Cr15, and its chemical composition is C: 1.40-1.60%, Cr: 12.0-14.0%.

[0007] As a further technical solution of the present invention, the preliminary processing includes cutting the raw material into the required rough size and performing preliminary turning or milling to adjust the basic shape of the steel ball, the hot rolling treatment includes heating the rough to the hot rolling temperature, the temperature range is controlled at 1100-1200°C, and rolling on a hot rolling mill to gradually shape the steel ball, controlling the rolling speed and temperature to maintain the required steel ball diameter and shape, and finally cooling the hot-rolled steel ball naturally or rapidly in the air to room temperature.

[0008] As a further technical solution of the present invention, the layered heat treatment includes core layer treatment, transition layer treatment and surface layer treatment, that is, the steel ball is heated to an appropriate temperature, the temperature is controlled at 870-900°C, and uniform heating is performed, and the steel ball is quickly immersed in oil or water for quenching to form a hardened layer, and finally tempered at 500-550°C to release internal stress and enhance toughness. The transition layer treatment includes heating the steel ball to a normalizing temperature, the temperature is controlled at 850-900°C, and then uniformly heated, uniformly After heating, it is cooled to room temperature to improve the uniformity and strength of the steel ball, and the steel ball is quenched, usually at 830-860°C, quickly cooled after heating, and finally tempered at 500-550°C to improve strength and wear resistance. The surface layer treatment includes heating the steel ball to the quenching temperature, the temperature is controlled at 830-860°C, and the steel ball is quickly immersed in oil or water for quenching to increase the surface hardness, and finally tempered at 150-200°C to enhance the wear resistance and reduce the brittleness of the surface layer.

[0009] As a further technical solution of the present invention, the surface cleaning includes using deionized water or solvent to clean the surface of the steel ball to remove grease and dirt, using a brush or ultrasonic cleaning equipment to ensure thorough cleaning, and the surface drying includes wiping with a clean cloth or using a drying device to accelerate drying.

[0010] As a further technical solution of the present invention, the material preheating includes preheating using an electric furnace, the temperature is controlled at 600-700°C, the time is controlled at 1 hour, and the steel ball is preheated to reduce the internal stress generated in the subsequent processing process. The material penetration includes using static carburizing treatment to ensure that the atmosphere is evenly distributed, and the gas flow rate is usually controlled at 5-10 L / min to ensure uniform penetration, wherein the atmosphere uses methane CH4 and acetylene C2H2 and a charge containing carbon powder, and is stably controlled at 930-980°C. The insulation time needs to be adjusted according to the size of the steel ball and the required carbonized layer thickness. The final cooling includes cooling using compressed air at a rate of no more than 100°C per hour until room temperature to avoid excessive cooling that causes an increase in internal stress.

[0011] As a further technical solution of the present invention, the nitriding pretreatment includes cleaning the surface of the steel ball to ensure that it is free of pollution, and preheating the steel ball, the temperature is controlled to 500°C, the time is 1 hour, for further preparation of nitriding treatment, the material nitriding includes gas nitriding treatment in a nitriding furnace, keeping the atmosphere stable and ensuring uniform distribution, wherein the atmosphere adopts a nitrogen-hydrogen mixed gas, the gas flow rate is usually 10-20 L / min, the temperature is controlled to 500-550°C, the holding time is adjusted according to the required hardness of the nitrided layer, the final cooling adopts air cooling, and the temperature is reduced at a rate of no more than 100°C per hour until room temperature, maintaining the hardness and stability of the nitrided layer.

[0012] As a further technical solution of the present invention, the surface shot peening is performed using a shot peening machine, the shot peening medium is silicon steel sand, the particle size range is controlled to be 0.3-0.6 mm, the shot peening pressure is controlled to be 4-6 bar, and the shot peening time is adjusted according to the size and surface state of the steel ball. The final cleaning includes using compressed air to thoroughly clean the residual particles after shot peening, and the air pressure is controlled to be 5-7 bar.

[0013] As a further technical solution of the present invention, the hardness test includes using a Rockwell hardness tester to test on the surface and different positions of the steel ball to ensure uniform hardness, with a target hardness range of HRC 62-65. The microstructure inspection includes observing the uniformity of the carbide layer and the nitride layer under a metallographic microscope, and preparing the sample using cutting, grinding and etching techniques to ensure that a clear hierarchical structure is observed. The wear test includes simulating the wear environment according to actual use conditions, namely, abrasive wear test and friction test, and recording the wear amount and performance changes to verify the wear resistance of the steel ball.

[0014] The beneficial effects of the present invention are as follows: 1. The present invention significantly improves the wear resistance of the steel ball by adopting a multi-layer structure design and a sophisticated heat treatment process. The core layer adopts medium carbon steel C45 to ensure the basic strength and toughness of the steel ball; the transition layer adopts low-alloy high-strength steel 16MnCr5, and through a reasonable heat treatment process, the uniformity and strength of the steel ball are enhanced, providing good support for the surface layer; the surface layer adopts high-chromium alloy steel Cr15, and its high chromium content significantly improves the surface hardness and wear resistance of the steel ball. In addition, carburizing and nitriding treatments further strengthen the surface of the steel ball, forming a hard carbide layer and a nitride layer, which effectively resist wear during use. These measures work together to enable the steel ball of the present invention to maintain a long service life under harsh working conditions, significantly reducing the replacement frequency and use cost.

[0015] 2. The present invention ensures the stability of the performance of the steel ball by finely controlling each link of the heat treatment process. The layered heat treatment process formulates different heating temperatures, holding times and cooling methods according to the characteristics of each layer of material, which not only ensures the full performance of the performance of each layer of material, but also avoids performance defects caused by uneven heating or improper cooling speed. At the same time, during the carburizing and nitriding process, the uniformity and quality of the carburized layer and the nitrided layer are ensured by precisely controlling parameters such as atmosphere composition, flow rate, temperature and holding time. In addition, surface shot peening further improves the roughness and stress state of the steel ball surface and improves its fatigue resistance. These optimization measures jointly ensure that the steel ball has stable performance after heat treatment and improve the reliability and consistency of the product.

[0016] 3. The present invention has established a comprehensive quality control system, from raw material selection, preliminary processing, hot rolling treatment, layered heat treatment, surface pretreatment, carburizing treatment, nitriding treatment, shot peening treatment to final quality inspection, each link is strictly controlled and inspected. The application of quality inspection methods such as hardness testing, microstructure inspection and wear testing ensures that the steel ball meets the design requirements in terms of hardness, organizational structure and wear resistance. This comprehensive quality control system not only improves the product qualification rate, but also enables the product to maintain stable performance during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a layered schematic diagram of the steel ball body structure of the present invention; Figure 2 This is a schematic diagram of the surface strengthening heat treatment process of the present invention; Figure 3 This is a schematic diagram of the process flow of surface pretreatment of the present invention; Figure 4It is a schematic diagram of the process flow of the infiltration treatment of the present invention; Figure 5 It is a schematic diagram of the process flow of nitriding treatment of the present invention; Figure 6 It is a schematic diagram of the process flow of shot peening treatment of the present invention; Figure 7 It is a schematic diagram of the process flow of quality inspection of the present invention.

[0018] In the figure: 1, steel ball body; 11, surface layer; 12, transition layer; 13, core layer. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] like Figures 1 to 7 As shown, in an embodiment of the present invention, a highly wear-resistant hot-rolled steel ball comprises a steel ball body 1, wherein the steel ball body 1 comprises a surface layer 11, a transition layer 12 and a core layer 13, wherein the surface of the core layer 13 is covered with the transition layer 12, and the surface of the transition layer 12 is covered with the surface layer 11; The surface strengthening heat treatment process includes the following steps: S1: preliminary processing; S2: Hot rolling treatment: S3: layered heat treatment; S4: surface pretreatment; S5: Carburizing treatment: S6: nitriding treatment; S7: Shot Peening: S8: Quality inspection; Surface heat treatment includes surface cleaning and surface drying, carburizing includes material preheating, material penetration and material cooling, nitriding includes nitriding pretreatment, material nitriding and final cooling, shot peening includes surface shot peening and final cleaning, quality inspection includes hardness test, microstructure inspection and wear test.

[0021] The highly wear-resistant hot-rolled steel ball has significantly improved its wear resistance through a precise layered structure and multi-step heat treatment process. From the core layer to the surface layer, the layer-by-layer strengthening design ensures the high strength and durability of the steel ball as a whole. In particular, through surface treatment technologies such as carburizing and nitriding, the hardness and wear resistance of the steel ball surface are effectively enhanced. Combined with shot peening, the surface roughness is further optimized and the wear resistance is improved. Finally, strict quality inspection ensures that each steel ball meets high standards, is suitable for high wear conditions, prolongs service life, reduces replacement frequency, and has significant economic benefits.

[0022] Among them, the core layer 13 is made of medium carbon steel C45, and its chemical composition is C: 0.42-0.50%, Mn: 0.50-0.80%, Si: ≤0.40%, P: ≤0.035%, S: ≤0.035%; the transition layer 12 is made of low alloy high strength steel 16MnCr5, and its chemical composition is C: 0.14-0.19%, Mn: 1.00-1.30%, Cr: 0.70-0.90%, Si: ≤0.40%, P: ≤0.035%, S: ≤0.035%; the surface layer 11 is made of high chromium alloy steel Cr15, and its chemical composition is C:1.40-1.60%, Cr: 12.0-14.0%.

[0023] C45 medium carbon steel is used as the core layer 13 to ensure the basic strength and toughness of the steel ball; the transition layer 12 uses 16MnCr5 low alloy high strength steel, and by adding appropriate amounts of manganese and chromium, the hardness and wear resistance of the steel ball are improved while maintaining good processing performance; the surface layer 11 uses high chromium alloy steel Cr15, whose high chromium content significantly enhances the corrosion resistance and wear resistance of the steel ball, allowing the steel ball to maintain excellent performance in harsh environments. This layered design combines the advantages of different materials and greatly improves the overall performance and service life of the steel ball.

[0024] Among them, the preliminary processing includes cutting the raw materials into the required rough size and performing preliminary turning or milling to adjust the basic shape of the steel ball. The hot rolling treatment includes heating the rough to the hot rolling temperature, the temperature range is controlled at 1100-1200°C, and rolling on a hot rolling mill to gradually shape the steel ball. The rolling speed and temperature are controlled to maintain the required steel ball diameter and shape. Finally, the hot-rolled steel ball is naturally cooled in the air or quickly cooled to room temperature.

[0025] The initial processing lays the foundation for the basic shape of the steel ball through precise cutting and turning / milling, providing a standardized starting point for subsequent processes. Hot rolling is a key step. Through high-temperature heating and precisely controlled rolling processes, the steel ball is not only gradually formed, but also the accuracy of the diameter and shape of the steel ball is ensured by regulating the rolling speed and temperature. The final natural or rapid cooling process stabilizes the organizational structure of the steel ball, laying a solid foundation for subsequent heat treatment and strengthening processes, and overall improving the processing efficiency and finished product quality of the steel ball.

[0026] The layered heat treatment includes core layer treatment, transition layer treatment and surface layer treatment, that is, the steel ball is heated to an appropriate temperature, the temperature is controlled at 870-900°C, and uniform heating is performed, and the steel ball is quickly immersed in oil or water for quenching to form a hardened layer, and finally tempered at 500-550°C to release internal stress and enhance toughness. The transition layer treatment includes heating the steel ball to the normalizing temperature, the temperature is controlled at 850-900°C, and then uniformly heated. After uniform heating, it is cooled to Room temperature to improve the uniformity and strength of the steel ball, and quench the steel ball, usually at 830-860°C, quickly cool it after heating, and finally temper it at 500-550°C to improve strength and wear resistance. The surface layer treatment includes heating the steel ball to the quenching temperature, the temperature is controlled at 830-860°C, and the steel ball is quickly immersed in oil or water for quenching to increase the surface hardness, and finally tempered at 150-200°C to enhance the wear resistance and reduce the brittleness of the surface layer.

[0027] Layered heat treatment strengthens each layer of the steel ball in a targeted manner by precisely controlling the temperature and cooling method. The core layer treatment enhances the overall toughness, the transition layer treatment improves the uniformity and strength, and the surface layer treatment significantly improves the wear resistance and hardness. This series of heat treatment processes not only ensures the balanced performance of the steel ball from the inside to the outside, but also greatly improves its wear resistance and service life, providing a solid guarantee for the stable operation of the steel ball under harsh working conditions.

[0028] Among them, surface cleaning includes using deionized water or solvent to clean the surface of the steel ball to remove grease and dirt, using a brush or ultrasonic cleaning equipment to ensure thorough cleaning, and surface drying includes wiping it dry with a clean cloth or using drying equipment to accelerate drying.

[0029] Surface cleaning and drying are important steps in the pretreatment of steel ball surfaces. Deionized water or high-efficiency solvents, combined with brushes or ultrasonic cleaning equipment, can thoroughly remove grease, dirt and tiny impurities on the surface of the steel ball, providing a clean base for subsequent surface treatment. Subsequent surface drying ensures that there is no residual moisture to avoid adverse effects on subsequent processes. This series of operations not only improves the cleanliness of the steel ball surface, but also creates ideal conditions for subsequent strengthening treatments such as carburizing and nitriding, thereby ensuring the overall improvement of the steel ball performance.

[0030] Among them, material preheating includes using an electric furnace for preheating, the temperature is controlled at 600-700°C, the time is controlled at 1 hour, and the steel ball is preheated to reduce the internal stress generated in the subsequent processing process. Material penetration includes using static carburizing treatment to ensure that the atmosphere is evenly distributed. The gas flow rate is usually controlled at 5-10 L / min to ensure uniform penetration. The atmosphere uses methane CH4 and acetylene C2H2 and a charge containing carbon powder, which is stably controlled at 930-980°C. The insulation time needs to be adjusted according to the size of the steel ball and the required carbonized layer thickness. The final cooling includes using compressed air for cooling, cooling at a rate of no more than 100°C per hour until room temperature, to avoid excessive cooling and increased internal stress.

[0031] Material preheating and penetration treatment are key links in carburizing and strengthening of steel balls. Preheating controls the temperature and time through an electric furnace, effectively reducing the internal stress in subsequent treatments and laying a good foundation for the carburizing process. Static carburizing treatment ensures uniform distribution of the atmosphere, promotes carbon elements to penetrate into the steel ball, and forms a solid carburized layer. The carefully controlled cooling process avoids the surge in internal stress and ensures the stability and improvement of the performance of the steel ball. This series of operations significantly enhances the surface hardness and wear resistance of the steel ball, providing reliable guarantee for its long-term service under harsh working conditions.

[0032] Among them, the nitriding pre-treatment includes cleaning the surface of the steel ball to ensure that there is no pollution, and preheating the steel ball with a temperature controlled at 500°C for 1 hour for further preparation for nitriding treatment. The material nitriding includes gas nitriding treatment in a nitriding furnace to keep the atmosphere stable and ensure uniform distribution. The atmosphere uses a nitrogen-hydrogen mixed gas with a gas flow rate of typically 10-20 L / min and a temperature control of 500-550°C. The holding time is adjusted according to the required hardness of the nitrided layer. The final cooling uses air cooling and is cooled at a rate of no more than 100°C per hour until it reaches room temperature to maintain the hardness and stability of the nitrided layer.

[0033] Nitriding pretreatment and nitriding treatment are key steps to improve the surface performance of steel balls. Pretreatment ensures the cleanliness and preheating of the steel ball surface, creating good conditions for the subsequent nitriding process. During the nitriding process, the stable nitrogen-hydrogen mixed gas atmosphere and the precisely controlled temperature promote the uniform formation of the nitriding layer, significantly improving the hardness and wear resistance of the steel ball surface. The slow cooling process maintains the stability of the nitriding layer and prevents performance degradation. This series of operations comprehensively improves the surface performance of the steel ball, making it more adaptable to high-wear and high-load working environments.

[0034] Among them, the surface shot peening is carried out by a shot peening machine, the shot peening medium is silicon steel sand, the particle size range is controlled to be 0.3-0.6 mm, the shot peening pressure is controlled to be 4-6 bar, and the shot peening time is adjusted according to the size and surface condition of the steel ball. The final cleaning includes using compressed air to thoroughly clean the residual particles after shot peening, and the air pressure is controlled to be 5-7 bar.

[0035] Surface shot peening uses a shot peening machine and selected silicon steel sand media to precisely strike the surface of the steel ball, effectively improving its surface roughness and stress state, and enhancing the surface's fatigue resistance and wear resistance. During the shot peening process, precisely controlled particle size, pressure and time ensure the uniformity of the treatment effect. The subsequent final cleaning step completely removes residual particles and keeps the surface of the steel ball clean and smooth. This series of operations not only improves the comprehensive performance of the steel ball, but also provides a more reliable quality guarantee for its subsequent applications.

[0036] Among them, the hardness test includes using a Rockwell hardness tester to test on the surface and different positions of the steel ball to ensure uniform hardness, with a target hardness range of HRC 62-65. The microstructure inspection includes observing the uniformity of the carbide layer and nitride layer under a metallographic microscope, and preparing the samples using cutting, grinding and etching techniques to ensure that a clear hierarchical structure is observed. The wear test includes simulating the wear environment according to actual use conditions, namely abrasive wear test and friction test, and recording the wear amount and performance changes to verify the wear resistance of the steel ball.

[0037] Hardness testing, microstructure inspection and wear testing together constitute a complete system for steel ball performance verification. Hardness testing ensures the uniformity of the surface and internal hardness of the steel ball to meet specific application requirements. Microstructure inspection reveals the microstructure of the carbide layer and nitride layer, verifying its uniformity and quality. Wear testing evaluates the wear resistance of the steel ball by simulating actual working conditions, providing direct evidence for the reliability of product quality. This series of testing methods ensures the quality control of steel balls during the manufacturing process and lays a solid foundation for their excellent performance in various applications.

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A highly wear-resistant hot-rolled steel ball, comprising a steel ball body (1), characterized in that: The steel ball body (1) comprises a surface layer (11), a transition layer (12) and a core layer (13); the surface of the core layer (13) is covered with the transition layer (12), and the surface of the transition layer (12) is covered with the surface layer (11); Surface strengthening heat treatment process, The following steps are involved: S1: preliminary processing; S2: Hot rolling treatment: S3: layered heat treatment; S4: surface pretreatment; S5: Carburizing treatment: S6: nitriding treatment; S7: Shot Peening: S8: Quality inspection; The surface heat treatment includes surface cleaning and surface drying, the carburizing treatment includes material preheating, material penetration and material cooling, the nitriding treatment includes nitriding pre-treatment, material nitriding and final cooling, the shot peening treatment includes surface shot peening and final cleaning, and the quality inspection includes hardness testing, microstructure inspection and wear testing.

2. A highly wear-resistant hot-rolled steel ball according to claim 1, characterized in that: The core layer (13) is made of medium carbon steel C45, and its chemical composition is C: 0.42-0.50%, Mn: 0.50-0.80%, Si: ≤0.40%, P: ≤0.035%, S: ≤0.035%. The transition layer (12) is made of low alloy high strength steel 16MnCr5, and its chemical composition is C: 0.14-0.19%, Mn: 1.00-1.30%, Cr: 0.70-0.90%, Si: ≤0.40%, P: ≤0.035%, S: ≤0.035%. The surface layer (11) is made of high chromium alloy steel Cr15, and its chemical composition is C: 1.40-1.60%, Cr: 12.0-14.0%.

3. The highly wear-resistant hot-rolled steel ball and the surface strengthening heat treatment process thereof according to claim 1, characterized in that: The preliminary processing includes cutting the raw material into the required rough size and performing preliminary turning or milling to adjust the basic shape of the steel ball. The hot rolling treatment includes heating the rough to the hot rolling temperature, the temperature range is controlled at 1100-1200°C, and rolling on a hot rolling mill to gradually shape the steel ball, controlling the rolling speed and temperature to maintain the required steel ball diameter and shape, and finally cooling the hot-rolled steel ball naturally or rapidly in the air to room temperature.

4. The highly wear-resistant hot-rolled steel ball and the surface strengthening heat treatment process thereof according to claim 1, characterized in that: The layered heat treatment includes core layer treatment, transition layer treatment and surface layer treatment, that is, heating the steel ball to an appropriate temperature, controlling the temperature at 870-900°C, uniformly heating, and quickly immersing the steel ball in oil or water for quenching to form a hardened layer, and finally tempering at 500-550°C to release internal stress and enhance toughness. The transition layer treatment includes heating the steel ball to a normalizing temperature, controlling the temperature at 850-900°C, and then uniformly heating. After uniform heating, cooling to Room temperature to improve the uniformity and strength of the steel ball, and the steel ball is quenched, usually at 830-860°C, quickly cooled after heating, and finally tempered at 500-550°C to improve strength and wear resistance. The surface layer treatment includes heating the steel ball to the quenching temperature, the temperature is controlled at 830-860°C, and the steel ball is quickly immersed in oil or water for quenching to increase the surface hardness, and finally tempered at 150-200°C to enhance the wear resistance and reduce the brittleness of the surface layer.

5. The highly wear-resistant hot-rolled steel ball and the surface strengthening heat treatment process thereof according to claim 1, characterized in that: The surface cleaning includes cleaning the surface of the steel ball with deionized water or solvent to remove grease and dirt, using a brush or ultrasonic cleaning equipment to ensure thorough cleaning, and the surface drying includes wiping with a clean cloth or using a drying device to accelerate drying.

6. The highly wear-resistant hot-rolled steel ball and the surface strengthening heat treatment process thereof according to claim 1, characterized in that: The material preheating includes preheating with an electric furnace, the temperature is controlled at 600-700°C, the time is controlled at 1 hour, and the steel ball is preheated to reduce the internal stress generated in the subsequent processing process. The material penetration includes using static carburizing treatment to ensure uniform distribution of the atmosphere. The gas flow rate is usually controlled at 5-10 L / min to ensure uniform penetration. The atmosphere uses methane CH4 and acetylene C2H2 and a charge containing carbon powder, which is stably controlled at 930-980°C. The insulation time needs to be adjusted according to the size of the steel ball and the required carbonized layer thickness. The final cooling includes cooling with compressed air at a rate of no more than 100°C per hour until room temperature to avoid excessive cooling that causes increased internal stress.

7. The highly wear-resistant hot-rolled steel ball and the surface strengthening heat treatment process thereof according to claim 1, characterized in that: The nitriding pre-treatment includes cleaning the surface of the steel ball to ensure that it is free of pollution, and preheating the steel ball, with the temperature controlled at 500°C for 1 hour, for further preparation of the nitriding treatment. The material nitriding includes gas nitriding treatment in a nitriding furnace, maintaining a stable atmosphere and ensuring uniform distribution, wherein the atmosphere uses a nitrogen-hydrogen mixed gas, the gas flow rate is usually 10-20 L / min, the temperature is controlled at 500-550°C, and the holding time is adjusted according to the required hardness of the nitrided layer. The final cooling uses air cooling and cools at a rate of no more than 100°C per hour until room temperature to maintain the hardness and stability of the nitrided layer.

8. The highly wear-resistant hot-rolled steel ball and the surface strengthening heat treatment process thereof according to claim 1, characterized in that: The surface shot peening is performed using a shot peening machine, the shot peening medium is silicon steel sand, the particle size range is controlled to be 0.3-0.6 mm, the shot peening pressure is controlled to be 4-6 bar, and the shot peening time is adjusted according to the size and surface condition of the steel ball. The final cleaning includes using compressed air to thoroughly clean the residual particles after shot peening, and the air pressure is controlled to be 5-7 bar.

9. The highly wear-resistant hot-rolled steel ball and the surface strengthening heat treatment process thereof according to claim 1, characterized in that: The hardness test includes using a Rockwell hardness tester to test on the surface and different positions of the steel ball to ensure uniform hardness, with a target hardness range of HRC 62-65. The microstructure inspection includes observing the uniformity of the carbide layer and the nitride layer under a metallographic microscope, and preparing the sample using cutting, grinding and etching techniques to ensure that a clear hierarchical structure is observed. The wear test includes simulating the wear environment according to actual use conditions, namely abrasive wear test and friction test, and recording the wear amount and performance changes to verify the wear resistance of the steel ball.

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