A heat treatment method for high-performance mining machinery castings

Abstract

This invention discloses a heat treatment method for high-performance mining machinery castings, comprising the following steps: S1: pretreatment; S2: multi-temperature zone gradient heating; S3: precise quenching and cooling; S4: residual stress elimination; S5: surface strengthening treatment; S6: cleaning. This invention, through a multi-temperature zone gradient heating design, combined with casting classification and stacking and ceramic gasket isolation, ensures uniform heating of all parts of the casting, completely eliminating soft spot defects, while avoiding coarse grains and improving the uniformity of the casting structure. By employing a combined thermal aging and vibration aging treatment, the residual stress elimination rate of the casting is ≥90%, effectively releasing the internal thermal and structural stresses of the casting, preventing later deformation and cracking, improving the dimensional stability of the casting, and extending the service life of the casting. Through shot peening and low-temperature tempering combined treatment, the surface hardness and wear resistance of the casting are improved, preventing early wear and further extending the service life of the casting.

Description

Technical Field

[0001] This invention belongs to the field of mining machinery casting processing technology, and specifically relates to a high-performance heat treatment method for mining machinery castings. Background Technology

[0002] Mining machinery castings are core components of mining, crushing, and conveying equipment. They operate in extremely harsh environments, enduring heavy loads, strong impacts, material erosion, and dust corrosion. Therefore, the comprehensive mechanical properties of the castings are extremely important, especially hardness, wear resistance, impact resistance, and crack resistance, which directly determine the operating efficiency and service life of the mining equipment. Currently, the heat treatment process for mining machinery castings mostly adopts a single-temperature zone heating mode. The uneven heating caused by stacking castings easily leads to soft spots, hardness differences exceeding 4 HRC, and a decrease in wear resistance of more than 30%. Simultaneously, insufficient temperature control precision during heating easily results in coarse grains in the casting structure, leading to defects such as Widmanstätten structure and network carbides, reducing the casting's toughness and impact resistance. Under heavy-load impact conditions, fracture failure is likely. Furthermore, without effective residual stress relief and surface strengthening treatment after heat treatment, oil residue remains on the casting surface, making subsequent cleaning difficult, and insufficient surface hardness leads to premature wear. Summary of the Invention

[0003] In view of the problems mentioned above in the background art, the purpose of this invention is to provide a high-performance heat treatment method for mining machinery castings.

[0004] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A heat treatment method for high-performance mining machinery castings includes the following steps: S1: Pretreatment: Clean the surface of the mining machinery castings to be heat-treated, removing oxide scale, rust, casting burrs and oil stains. Rinse the surface of the castings with a high-pressure water gun, and then put the castings into a drying oven and dry them at 120-150℃ for 2-3 hours to make the moisture content of the castings ≤0.5%. After the pretreatment is completed, the castings are evenly stacked on a high-temperature resistant corundum tray. S2: Multi-temperature zone gradient heating. The tray containing the qualified castings in S1 is sent into a continuous multi-temperature zone heating furnace, and the castings in the tray are heated step by step through the four independent temperature zones of the heating furnace. S3: Precision quenching and cooling. After the multi-temperature zone heating and heat preservation in S2 is completed, the casting is pushed out of the heating furnace and transferred to the quenching drum. The casting is fully turned over 360° in the quenching drum to ensure that each casting can be in uniform contact with the quenching liquid in the quenching drum. S4: Residual stress elimination. The castings after S3 quenching are sent into an aging furnace and a combined thermal aging and vibration aging treatment is used to ensure that the residual stress elimination rate of the castings is ≥90%, thus avoiding deformation and cracking of the castings in the later stage. S5: Surface strengthening treatment. The castings after S4 to eliminate residual stress are shot peened. The high-speed impact of the shot on the casting surface causes plastic deformation of the surface layer, forming a residual compressive stress layer and improving the surface hardness. After shot peening, the castings are subjected to low-temperature tempering and then cooled to room temperature in the furnace to further stabilize the casting structure, improve the casting toughness, and prevent surface cracks after shot peening. S6: Cleaning. Place the surface-strengthened casting into a special cleaning tank and use an alkaline cleaning agent to remove quenching liquid residue, oil stains, and shot blasting dust from the surface of the casting. After cleaning, place the casting into a drying oven and dry it at 100-120℃ for 1-2 hours to ensure that the surface of the casting is dry and free of residue, and finally obtain a high-performance mining machinery casting.

[0005] Further specifying that in S1, after drying, non-destructive testing is performed to remove castings with defects such as cracks, porosity, and shrinkage cavities, and qualified castings are classified according to size specifications to avoid uneven heating caused by mixing castings of different sizes.

[0006] Further specified, in S1, an alumina ceramic gasket with a thickness of 5-8 mm is laid at the bottom of the tray to avoid direct contact between the casting and the tray, resulting in adhesion and local overheating.

[0007] Further specified, in S2, the first temperature zone is set at 550-600℃ and held for 1.5-2.5 hours to eliminate casting stress in the casting; the second temperature zone is set at 650-750℃ and held for 1.5-2.5 hours to achieve initial homogenization of the casting structure; the third temperature zone is set at 800-900℃ and held for 1.5-2.5 hours to allow full diffusion of alloying elements in the casting; and the fourth temperature zone is set at 950-1020℃ and held for 1.5-2.5 hours to achieve complete austenitization of the casting. The heating rate of all four temperature zones is controlled at 5-8℃ / min, and the total holding time is 6-10 hours to ensure uniform heating of all parts of the casting and avoid the occurrence of soft spots.

[0008] Further specified, in S3, the quenching fluid is an oil-like quenching fluid, the initial temperature of the quenching fluid is preheated to 40-50℃, the quenching time is controlled to 8-12 minutes, the temperature of the quenching fluid is monitored in real time during the quenching process, and when the temperature exceeds 50℃, circulating cooling water is introduced to reduce the temperature of the quenching fluid to 30-50℃.

[0009] Further specifying that in S4, firstly, a thermal aging treatment is performed, with the aging temperature set at 200-250℃ and held for 4-6 hours. The heating rate is controlled at 3-5℃ / min. Subsequently, the furnace is cooled to room temperature. Atomic diffusion is promoted through a thermal activation mechanism to achieve initial stress release. Then, a vibration aging treatment is performed. The resonant frequency of the casting is determined through finite element analysis. The excitation force is controlled at 0.5-1.5 times the weight of the casting, and the vibration time is 20-30 minutes. Dislocation reorganization is promoted through mechanical energy conversion to further release the residual stress inside the casting.

[0010] Further specified, in S5, cast steel shot is used as the projectile, the projectile diameter is 0.8 to 1.2 mm, the shot peening pressure is 0.4 to 0.6 MPa, the shot peening time is 15 to 20 minutes, and the shot peening coverage is ≥200%.

[0011] Further specified, in S5, the tempering temperature is 180-220°C, the holding time is 2-3 hours, and the heating rate is controlled at 2-4°C / min.

[0012] Further specifying that in S6, the alkaline cleaning agent is a mixture of sodium hydroxide and sodium carbonate in a weight ratio of 2:1, with a concentration of 5-8%, a cleaning temperature of 60-70°C, and a cleaning time of 15-20 minutes.

[0013] The beneficial effects of this invention are as follows: 1. This invention uses a multi-temperature zone gradient heating design, combined with casting classification and stacking and ceramic gasket isolation, to ensure uniform heating of all parts of the casting, completely eliminate soft spot defects, avoid coarse grains, and improve the uniformity of the casting structure.

[0014] 2. This invention employs a combined thermal aging and vibration aging treatment method to achieve a residual stress elimination rate of ≥90% in castings, effectively releasing internal thermal and structural stresses, preventing later deformation and cracking, improving dimensional stability, and extending the service life of castings.

[0015] 3. This invention uses alkaline cleaning agents to quickly remove oil and impurities from the surface of castings, reducing cleaning difficulty and avoiding corrosion caused by residual impurities. Through shot peening and low-temperature tempering combined treatment, the surface hardness and wear resistance of the castings are improved, preventing premature wear and further extending the service life of the castings. Attached Figure Description

[0016] The present invention can be further illustrated by the non-limiting embodiments given in the accompanying drawings; Figure 1 This is a schematic flowchart of a heat treatment method for high-performance mining machinery castings according to an embodiment of the present invention; Detailed Implementation To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0017] like Figure 1 As shown, a high-performance mining machinery casting heat treatment method of the present invention includes the following steps: S1: Pretreatment: Clean the surface of the mining machinery castings to be heat-treated, removing oxide scale, rust, casting burrs and oil stains. Rinse the surface of the castings with a high-pressure water gun, and then put the castings into a drying oven and dry them at 120-150℃ for 2-3 hours to make the moisture content of the castings ≤0.5%. After the pretreatment is completed, the castings are evenly stacked on a high-temperature resistant corundum tray. S2: Multi-temperature zone gradient heating. The tray containing the qualified castings in S1 is sent into a continuous multi-temperature zone heating furnace, and the castings in the tray are heated step by step through the four independent temperature zones of the heating furnace. S3: Precision quenching and cooling. After the multi-temperature zone heating and heat preservation in S2 is completed, the casting is pushed out of the heating furnace and transferred to the quenching drum. The casting is fully turned over 360° in the quenching drum to ensure that each casting can be in uniform contact with the quenching liquid in the quenching drum. S4: Residual stress elimination. The castings after S3 quenching are sent into an aging furnace and a combined thermal aging and vibration aging treatment is used to ensure that the residual stress elimination rate of the castings is ≥90%, thus avoiding deformation and cracking of the castings in the later stage. S5: Surface strengthening treatment. The castings after S4 to eliminate residual stress are shot peened. The high-speed impact of the shot on the casting surface causes plastic deformation of the surface layer, forming a residual compressive stress layer and improving the surface hardness. After shot peening, the castings are subjected to low-temperature tempering and then cooled to room temperature in the furnace to further stabilize the casting structure, improve the casting toughness, and prevent surface cracks after shot peening. S6: Cleaning. Place the surface-strengthened casting into a special cleaning tank and use an alkaline cleaning agent to remove quenching liquid residue, oil stains, and shot blasting dust from the surface of the casting. After cleaning, place the casting into a drying oven and dry it at 100-120℃ for 1-2 hours to ensure that the surface of the casting is dry and free of residue, and finally obtain a high-performance mining machinery casting.

[0018] Preferably, in S1, non-destructive testing is performed on the dried castings to remove those with defects such as cracks, porosity, and shrinkage cavities. The qualified castings are classified according to their size and specifications to avoid uneven heating caused by mixing castings of different sizes.

[0019] Preferably, in S1, an alumina ceramic gasket with a thickness of 5-8 mm is laid at the bottom of the tray to prevent the casting from directly contacting the tray and causing adhesion and local overheating.

[0020] Preferably, in S2, the first temperature zone is set at 550–600℃ and held for 1.5–2.5 hours to eliminate casting stress in the casting; the second temperature zone is set at 650–750℃ and held for 1.5–2.5 hours to achieve initial homogenization of the casting structure; the third temperature zone is set at 800–900℃ and held for 1.5–2.5 hours to allow for full diffusion of alloying elements in the casting; and the fourth temperature zone is set at 950–1020℃ and held for 1.5–2.5 hours to achieve complete austenitization of the casting. The heating rate of all four temperature zones is controlled at 5–8℃ / min, and the total holding time is 6–10 hours to ensure uniform heating of all parts of the casting and avoid soft spots.

[0021] Preferably, in S3, the quenching fluid is an oil-like quenching fluid, the initial temperature of the quenching fluid is preheated to 40-50℃, the quenching time is controlled to be 8-12 minutes, the temperature of the quenching fluid is monitored in real time during the quenching process, and when the temperature exceeds 50℃, circulating cooling water is introduced to reduce the temperature of the quenching fluid to 30-50℃.

[0022] Preferably, in step S4, a thermal aging treatment is first performed, with the aging temperature set at 200–250°C and held for 4–6 hours. The heating rate is controlled at 3–5°C / min. Subsequently, the furnace is cooled to room temperature. The thermal activation mechanism promotes atomic diffusion, achieving initial stress release. Then, a vibration aging treatment is performed. The resonant frequency of the casting is determined through finite element analysis. The excitation force is controlled at 0.5–1.5 times the weight of the casting, and the vibration time is 20–30 minutes. The mechanical energy conversion promotes dislocation reorganization, further releasing the residual stress inside the casting.

[0023] Preferably, in S5, cast steel shot is used as the projectile, with a projectile diameter of 0.8 to 1.2 mm, a shot peening pressure of 0.4 to 0.6 MPa, a shot peening time of 15 to 20 minutes, and a shot peening coverage of ≥200%.

[0024] Preferably, in S5, the tempering temperature is 180-220℃, the holding time is 2-3 hours, and the heating rate is controlled at 2-4℃ / min.

[0025] Preferably, in step S6, the alkaline cleaning agent is a mixture of sodium hydroxide and sodium carbonate in a weight ratio of 2:1, with a concentration of 5-8%, a cleaning temperature of 60-70°C, and a cleaning time of 15-20 minutes.

[0026] In this embodiment, the surface of the mining machinery castings to be heat-treated is washed with a high-pressure water gun to remove surface oxide scale, rust, casting burrs, and oil stains. They are then placed in a drying oven and dried at 130°C for 2.5 hours, resulting in a moisture content of 0.3%. Ultrasonic non-destructive testing equipment is used to inspect the castings, rejecting defective ones. Qualified castings are sorted by size and evenly stacked on high-temperature corundum trays. A 6mm thick alumina ceramic pad is placed at the bottom of the tray to ensure no direct contact between the castings and the tray. The trays containing qualified castings are then conveyed via a conveyor chain into a continuous multi-temperature zone heating furnace. This furnace is divided into four independent temperature zones, each independently controlled by a PID temperature control system with a temperature control accuracy of ±2°C. The temperature zones are separated by a [missing information - likely a typo, should be "set"]. The ceramic fiber insulation layer has four temperature zones: Zone 1 at 580℃ for 2 hours, Zone 2 at 700℃ for 2 hours, Zone 3 at 850℃ for 2 hours, and Zone 4 at 980℃ for 2 hours. The heating rate for each zone is controlled at 6℃ / min, with a total holding time of 8 hours. A thermocouple array collects temperature data every 10 seconds, adjusting the heating power in real time to ensure temperature fluctuations in each zone do not exceed ±3℃. After heating and holding, the castings are removed from the furnace and transferred to a quenching drum, where they are rotated 360° to ensure uniform contact between each casting and the quenching liquid. The quenching liquid is preheated to 45℃, and the quenching time is controlled at 10 minutes. During the process, the temperature of the quenching fluid was monitored in real time using a platinum resistance temperature sensor. When the temperature reached 52℃, 18℃ circulating cooling water was introduced into the cooling jacket outside the quenching drum at a flow rate of 12L / min to lower the quenching fluid temperature to 42℃. The quenched casting was then sent to an aging furnace for initial thermal aging treatment. The aging temperature was set at 220℃, the heating rate was controlled at 4℃ / min, and the holding time was 5 hours. Subsequently, the casting was cooled to room temperature in the furnace and then subjected to vibration aging treatment. Finite element analysis determined the resonant frequency of the casting to be 85Hz. The excitation force was controlled at 1.0 times the weight of the casting, and the vibration time was 25 minutes. After the treatment, the residual stress elimination rate of the casting was found to be 92%. Finally, the casting was shot-peened with cast steel shot with a shot diameter of 1 mm. The shot peening process was as follows: 0mm diameter, shot peening pressure 0.5MPa, shot peening time 18 minutes, shot peening gun angle with casting surface 50°, distance 180mm, shot peening coverage 220%. After shot peening, the casting was sent to a tempering furnace, tempering temperature set to 200℃, heating rate controlled at 3℃ / min, held for 2.5 hours, and then cooled to room temperature with the furnace. Infrared thermometer was used to detect the surface temperature of the casting to ensure uniform cooling. The surface-strengthened casting was placed in a special cleaning tank and cleaned with an alkaline cleaning agent of sodium hydroxide and sodium carbonate mixed in a weight ratio of 2:1, concentration 6%, cleaning temperature 65℃, cleaning time 18 minutes. After cleaning, the casting was placed in a drying oven and dried at 110℃ for 1.5 hours to ensure the surface was dry and without residue.

[0027] High-pressure rinsing removes oxide scale, oil stains, and other impurities from the casting surface, preventing these impurities from forming oxide inclusions during heating and affecting the uniformity of the casting structure. Drying removes internal moisture from the casting, preventing moisture from vaporizing and causing defects such as porosity during heating. Non-destructive testing allows for the early rejection of unqualified castings, avoiding waste of subsequent heat treatment resources. The classification and stacking of castings, along with the isolation of ceramic gaskets, prevents uneven heating caused by mixing castings of different sizes and also prevents castings from sticking to the tray and causing localized overheating, laying the foundation for uniform heating in the future. Employing a multi-temperature zone independent heating structure, the heating process is divided into four gradient temperature zones. Each zone is independently controlled by a PID temperature control system. Combined with multi-point temperature measurement and real-time feedback from a thermocouple array, precise temperature control with an accuracy of ±2℃ is achieved, solving the problem of insufficient temperature control accuracy in traditional single-temperature zone heating. The ceramic fiber insulation layer between each temperature zone effectively reduces thermal coupling effects and avoids temperature gradient disorder caused by heat transfer between temperature zones. The gradient heating and segmented heat preservation design allows the casting to be heated gradually. First, the casting stress is eliminated in the low-temperature zone, then the microstructure is homogenized and alloy element diffusion is achieved in the medium-temperature zone, and finally, complete austenitization is achieved in the high-temperature zone. This ensures uniform heating and grain refinement in all parts of the casting, fundamentally preventing defects such as soft spots and coarse grains, and providing a guarantee for the improvement of subsequent quenching performance. The casting is in uniform contact with the quenching fluid, which solves the problem of excessive hardness difference caused by uneven local cooling of the casting during the traditional quenching process. The selection of oil-like quenching fluid can take into account both cooling speed and toughness protection, avoid the generation of quenching cracks, and maintain the temperature of the quenching fluid through the cooling jacket to ensure the consistency of quenching quality. A combination of thermal aging and vibration aging is employed. Thermal aging involves heating the casting to a low temperature range of 200–250°C, which enhances atomic diffusion through thermal activation, promoting dislocation slip and climb, and achieving initial release of internal thermal and structural stresses. Vibration aging involves applying an excitation force that matches the resonant frequency of the casting, converting mechanical energy into internal energy, which promotes the dislocation lines to unpin and redistribute, further releasing residual stress. The synergistic effect of both methods can achieve a residual stress elimination rate of ≥90%, preventing later deformation and cracking of the casting, and improving the dimensional stability and crack resistance of the casting. Shot peening utilizes high-speed impact of cast steel shot on the surface of castings, causing cyclic plastic deformation of the surface layer. This results in grain breakage and lattice distortion, forming a residual compressive stress layer with a depth of 0.1–0.7 mm. This transforms the tensile stress on the surface into compressive stress, effectively inhibiting the initiation and propagation of fatigue cracks. At the same time, it increases the surface hardness by 15–20%. Subsequent low-temperature tempering can eliminate the surface stress generated during shot peening, stabilize the casting structure, prevent the formation of surface cracks, and balance surface hardness and toughness, further improving the wear resistance and impact resistance of the casting. Alkaline cleaning agents can chemically react with quenching fluid residue and oil stains on the surface of castings, quickly removing surface impurities and avoiding surface corrosion and potential problems in subsequent processing caused by impurity residue; drying treatment can ensure that the surface of the casting is dry and prevent moisture residue from causing rust.

[0028] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A heat treatment method for high-performance mining machinery castings, characterized in that: Includes the following steps: S1: Pretreatment: Clean the surface of the mining machinery castings to be heat-treated, removing oxide scale, rust, casting burrs and oil stains. Rinse the surface of the castings with a high-pressure water gun, and then put the castings into a drying oven and dry them at 120-150℃ for 2-3 hours to make the moisture content of the castings ≤0.5%. After the pretreatment is completed, the castings are evenly stacked on a high-temperature resistant corundum tray. S2: Multi-temperature zone gradient heating. The tray containing the qualified castings in S1 is sent into a continuous multi-temperature zone heating furnace, and the castings in the tray are heated step by step through the four independent temperature zones of the heating furnace. S3: Precision quenching and cooling. After the multi-temperature zone heating and heat preservation in S2 is completed, the casting is pushed out of the heating furnace and transferred to the quenching drum. The casting is fully turned over 360° in the quenching drum to ensure that each casting can be in uniform contact with the quenching liquid in the quenching drum. S4: Residual stress elimination. The castings after S3 quenching are sent into an aging furnace and a combined thermal aging and vibration aging treatment is used to ensure that the residual stress elimination rate of the castings is ≥90%, thus avoiding deformation and cracking of the castings in the later stage. S5: Surface strengthening treatment. The castings after S4 to eliminate residual stress are shot peened. The high-speed impact of the shot on the casting surface causes plastic deformation of the surface layer, forming a residual compressive stress layer and improving the surface hardness. After shot peening, the castings are subjected to low-temperature tempering and then cooled to room temperature in the furnace to further stabilize the casting structure, improve the casting toughness, and prevent surface cracks after shot peening. S6: Cleaning. Place the surface-strengthened casting into a special cleaning tank and use an alkaline cleaning agent to remove quenching liquid residue, oil stains, and shot blasting dust from the surface of the casting. After cleaning, place the casting into a drying oven and dry it at 100-120℃ for 1-2 hours to ensure that the surface of the casting is dry and free of residue, and finally obtain a high-performance mining machinery casting.

2. The heat treatment method for high-performance mining machinery castings according to claim 1, characterized in that: In step S1, non-destructive testing is performed on the dried castings to remove those with defects such as cracks, porosity, and shrinkage cavities. The qualified castings are then classified according to their size specifications to avoid uneven heating caused by mixing castings of different sizes.

3. The heat treatment method for high-performance mining machinery castings according to claim 2, characterized in that: In step S1, an alumina ceramic pad with a thickness of 5-8 mm is laid at the bottom of the tray to prevent the casting from directly contacting the tray and causing adhesion and local overheating.

4. The heat treatment method for high-performance mining machinery castings according to claim 3, characterized in that: In S2, the first temperature zone is set at 550–600℃ and held for 1.5–2.5 hours to eliminate casting stress in the casting; the second temperature zone is set at 650–750℃ and held for 1.5–2.5 hours to achieve initial homogenization of the casting structure; the third temperature zone is set at 800–900℃ and held for 1.5–2.5 hours to allow for full diffusion of alloying elements in the casting; and the fourth temperature zone is set at 950–1020℃ and held for 1.5–2.5 hours to achieve complete austenitization of the casting. The heating rate of all four temperature zones is controlled at 5–8℃ / min, and the total holding time is 6–10 hours to ensure uniform heating of all parts of the casting and avoid soft spots.

5. The heat treatment method for high-performance mining machinery castings according to claim 4, characterized in that: In S3, the quenching fluid is an oil-like quenching fluid. The initial temperature of the quenching fluid is preheated to 40-50°C, and the quenching time is controlled to be 8-12 minutes. The temperature of the quenching fluid is monitored in real time during the quenching process. When the temperature exceeds 50°C, circulating cooling water is introduced to reduce the temperature of the quenching fluid to 30-50°C.

6. The heat treatment method for high-performance mining machinery castings according to claim 5, characterized in that: In step S4, thermal aging is first performed, with the aging temperature set at 200–250°C and held for 4–6 hours. The heating rate is controlled at 3–5°C / min. Subsequently, the casting is cooled to room temperature in the furnace. Atomic diffusion is promoted through a thermal activation mechanism to achieve initial stress release. Then, vibration aging is performed. The resonant frequency of the casting is determined through finite element analysis. The excitation force is controlled at 0.5–1.5 times the weight of the casting, and the vibration time is 20–30 minutes. Dislocation reorganization is promoted through mechanical energy conversion to further release the residual stress inside the casting.

7. The heat treatment method for high-performance mining machinery castings according to claim 6, characterized in that: In S5, cast steel shot is used as the projectile, with a projectile diameter of 0.8 to 1.2 mm, a shot peening pressure of 0.4 to 0.6 MPa, a shot peening time of 15 to 20 minutes, and a shot peening coverage of ≥200%.

8. The heat treatment method for high-performance mining machinery castings according to claim 7, characterized in that: In S5, the tempering temperature is 180-220℃, the holding time is 2-3 hours, and the heating rate is controlled at 2-4℃ / min.

9. A heat treatment method for high-performance mining machinery castings according to claim 8, characterized in that: In step S6, the alkaline cleaning agent is a mixture of sodium hydroxide and sodium carbonate in a weight ratio of 2:1, with a concentration of 5-8%, a cleaning temperature of 60-70°C, and a cleaning time of 15-20 minutes.

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