Forging method of forge piece and forge piece

Abstract

The forging method comprises the following steps that S1, a qualified raw material is cut into a forge piece blank with the required size, the cut forge piece blank is polished, and burrs and an oxide layer on the cutting edge are removed; s2, the forging blank is preheated at a low temperature, the forging blank is heated to 400-500 DEG C, the heating speed is controlled to be 80-100 DEG C / h, and heat preservation is conducted for 1-1.5 h; s3, the forge piece blank is heated at a high temperature, the forge piece blank is heated to 1050-1150 DEG C, the heating speed is adjusted to be 120-150 DEG C / h, heat preservation is conducted for 2-3 hours at the temperature, and the forge piece blank is fully austenitized; according to the sectional heating process of raw material pretreatment and inert gas protection, the phenomena of blank surface decarburization and overheating and overburning are effectively avoided, the uniformity and stability of blank tissue are guaranteed, the internal residual stress of the forge piece can be effectively controlled according to a cooling curve set according to the characteristics of the forge piece, and deformation and cracking of the forge piece are avoided; and the size precision and stability of the forge piece are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of forgings, and in particular to a forging method and the forging. Background Art

[0002] Existing forging methods have numerous shortcomings. Traditional forging processes often struggle to precisely control the uniformity of metal deformation during the forging process, which can easily lead to uneven internal microstructures in forgings, coarse grains in some areas, and texture defects in others, severely impacting the forging's overall mechanical properties, such as strength, toughness, and fatigue life. During the heating process, inaccurate control of the heating rate and holding time can easily lead to surface decarburization or overheating, reducing the forging's surface quality and overall performance. Furthermore, traditional forging die design lacks in-depth consideration of metal flow characteristics. During the forging of complex-shaped forgings, metal flow is hindered, requiring higher forging forces and causing increased die wear, reducing die life, and increasing production costs. Furthermore, post-forging cooling often relies on natural cooling or simple air or water cooling, failing to precisely control cooling based on the forging's material, shape, and size. This results in significant residual stresses within the forging, which can easily cause deformation, cracking, and other problems. Based on this, a forging method and forging are designed. Summary of the Invention

[0003] To overcome at least one of the aforementioned drawbacks of the prior art, the present invention provides a forging method and forging. The segmented heating process and inert gas protection during raw material pretreatment effectively prevent surface decarburization and overheating of the billet, ensuring uniformity and stability of the billet structure. A cooling curve tailored to the forging's characteristics effectively controls residual stress within the forging, preventing deformation and cracking, and improving the forging's dimensional accuracy and stability.

[0004] The technical solution adopted by the present invention to solve the problem is:

[0005] A forging method comprises the following steps: S1, cutting qualified raw materials into forging blanks of required sizes, grinding the cut forging blanks to remove burrs and oxide layers on the cut edges; S2, preheating the forging blanks at a low temperature, heating the forging blanks to 400-500°C, controlling the heating rate at 80-100°C / h, and keeping the temperature at that temperature for 1-1.5 hours; S3, heating the forging blanks at a high temperature, heating the forging blanks to 1050-1150°C, adjusting the heating rate at 120-150°C / h, and keeping the temperature at that temperature for 2-3 hours to fully austenitize the forging blanks; S4 1. Use a forging machine to perform multi-directional forging on the forging blank, and then perform upsetting and drawing treatment after multi-directional forging; S5. Transfer the forging to a cooling device for cooling, and accurately set the cooling curve according to the shape and size of the forging; S6. The cooled forging is heat treated by first heating the forging to 850-900℃, keeping it warm for 1.5-2.5 hours, and then performing oil quenching. The quenching oil temperature is controlled at 40-60℃; tempering treatment is immediately performed after quenching. The tempering temperature is 550-650℃, and the temperature is kept warm for 2-3 hours. The number of tempering times is 2 times; S7. The forgings after heat treatment are shot peened and ground.

[0006] By adopting the above scheme, the segmented heating process and inert gas protection for raw material pretreatment effectively avoid decarburization and overheating of the billet surface, ensuring the uniformity and stability of the billet structure; and through the forging machine and multi-directional forging process, precise control of metal deformation is achieved, which significantly improves the uniformity and refinement of the internal structure of the forging, and enhances the comprehensive mechanical properties of the forging; the cooling curve set according to the characteristics of the forging can effectively control the internal residual stress of the forging, avoid deformation and cracking of the forging, and improve the dimensional accuracy and stability of the forging; the post-forging treatment process combining shot peening and grinding finishing is adopted to further optimize the internal structure and surface properties of the forging, so that the forging can achieve a better balance in terms of strength, toughness, fatigue life and surface quality.

[0007] Furthermore, in step S1, the raw material is cut by laser cutting, and the deviation range between the cut forging blank and the design size is controlled within ±0.3 mm, and the surface roughness Ra of the forging blank during the grinding process is less than 1.2 μm.

[0008] By adopting the above solution, the laser cutting technology is mature, the cutting effect is better, and the burrs and oxidation on the cutting edge can be removed by grinding.

[0009] Furthermore, during the heating process of step S2 and the heating process of step S3, an inert gas is used to prevent oxidation and decarburization of the surface of the forging blank.

[0010] By adopting the above scheme, oxidation and decarburization of the blank surface are prevented by introducing inert gas.

[0011] Furthermore, in step S4, multi-directional forging is to apply different forging forces in sequence along the X-axis, Y-axis and Z-axis of the forging blank, and the ratio of the forging forces of the X-axis, Y-axis and Z-axis is pre-set according to the shape and performance requirements of the forging.

[0012] By adopting the above scheme, the internal structure of the billet is made more uniform and refined through multi-directional forging.

[0013] Furthermore, in step S5: when the forging is a shaft forging, among which, those with a length of less than 600 mm and a diameter of less than 60 mm are small-sized shaft forgings, after forging is completed, the temperature is first rapidly cooled to 500-600°C at a rate of 120-150°C / min, and then slowly cooled to room temperature at a rate of 30-40°C / min; among which, those with a length between 600 mm and 1200 mm and a diameter between 60 mm and 120 mm are medium-sized shaft forgings, after forging is completed, the temperature is first cooled to 550-650°C at a rate of 80-120°C / min, and then cooled to room temperature at a rate of 20-30°C / min; among which, those with a length greater than 1200 mm and a diameter greater than 120 mm are large-sized shaft forgings, and after forging is completed, slow cooling is adopted throughout the process, and the cooling rate is controlled at 10-20°C / min.

[0014] By adopting the above scheme, small-sized shaft forgings have a relatively large surface area, fast heat dissipation, and relatively small internal thermal stress, and can withstand a relatively fast initial cooling rate, while slow cooling in the later stage can avoid excessive tissue stress caused by excessive cooling and leading to cracks; the thermal conductivity characteristics of medium-sized shaft forgings are between small and large sizes. Such a cooling curve can balance thermal stress and tissue stress, prevent deformation and cracking, and ensure certain mechanical properties at the same time; large-sized shaft forgings have more internal heat accumulation, and excessive cooling will cause huge thermal stress, which is easy to cause cracks or even fractures. The use of slow cooling throughout the process can make the internal and external temperatures drop evenly, reducing stress concentration.

[0015] Furthermore, in step S5: when the forging is a disc forging, among them, those with a thickness of less than 50 mm are thin disc forgings, and after forging is completed, they are first air-cooled for 1-2 minutes to reduce the temperature of their surface, and then air-cooled to 500-600°C at a rate of 80-100°C / min, and finally slowly cooled to room temperature at a rate of 25-35°C / min; among them, those with a thickness between 50 mm and 150 mm are medium-thick disc forgings, and after forging is completed, spray cooling is used to reduce the forging temperature to 600-700°C, and the spray cooling rate is controlled at 60-80°C / min, and then slowly cooled to room temperature at a rate of 5-25°C / min; among them, those with a thickness greater than 150 mm are thick disc forgings, and after forging is completed, they are slowly cooled, and the cooling rate is controlled at 8-15°C / min.

[0016] By adopting the above scheme, thin disc forgings have a large surface area, and the initial cooling by air cooling can reduce the temperature difference between the surface and the core during subsequent air cooling. Air cooling can use its large surface area to quickly dissipate heat, and slow cooling in the later stage can ensure uniformity of the structure; medium and thick disc forgings use spray cooling to quickly remove heat in the early stage, and it is more uniform than air cooling, and slow cooling in the later stage can avoid excessive stress in the structure; the internal heat of thick disc forgings is not easy to dissipate, and slow cooling in the furnace can provide a more stable cooling environment, reducing the stress caused by excessive temperature gradient.

[0017] Further, in step S5: when the forging is a complex shape forging, wherein the size is between 100mm-500mm, and the inner cavity diameter is less than 50mm or the boss height is less than 30mm, it is a small complex shape forging. After forging, it is first cooled to 500-600℃ at a rate of 60-90℃ / min, and then slowly cooled to room temperature at a rate of 20-30℃ / min; wherein the size is between 500mm-1000mm, and the inner cavity diameter is between 50mm-100mm or the boss height is between 30mm -60mm are medium-sized complex-shaped forgings. After forging, they are first cooled naturally in the air for 3-5 minutes, then cooled to 550-650℃ at a rate of 40-70℃ / min, and finally slowly cooled to room temperature at a rate of 15-25℃ / min; among them, large complex-shaped forgings are those with a size greater than 1000mm, and whose inner cavity diameter is greater than 100mm or whose boss height is greater than 60mm. After forging, they are first kept isothermally at 700-800℃ for 1-2 hours, then cooled to 300-400℃, and finally air-cooled to room temperature.

[0018] By adopting the above scheme, although small complex-shaped forgings have complex structures, they are small in overall size and have relatively fast heat dissipation. They are cooled moderately quickly in the early stage and slowly cooled in the later stage to balance the stress. Medium-sized complex-shaped forgings are cooled naturally to initially balance the surface and internal temperatures. Oil cooling can control the cooling rate and make the cooling relatively uniform. Slow cooling ensures the microstructure performance. Large complex-shaped forgings have complex thermal stresses and microstructure stresses. Isothermal furnace cooling can make the internal structure transform evenly, reducing the risk of stress concentration and deformation.

[0019] Furthermore, in step S7, the shot peening treatment uses steel shots with a shot diameter of 0.3-0.8 mm and a shot peening intensity of 0.25-0.4A; the grinding process uses a CNC grinder to reduce the surface roughness Ra of the forging to 0.8-1.6 μm.

[0020] By adopting the above scheme, a compressive stress layer is formed on the surface of the forging by shot peening, thereby improving its fatigue resistance and surface hardness. The grinding process uses a high-precision CNC grinder to reduce the surface roughness Ra of the forging to 0.8-1.6μm, ensuring that the dimensional accuracy and surface finish of the forging meet the high-precision assembly requirements.

[0021] A forging comprises the following components by mass percentage: carbon: 0.2-0.4%; nickel 1.5-2.5%; chromium 0.8-1.2%; molybdenum 0.15-0.25%; vanadium 0.05-0.15%; the balance being iron and trace impurity elements.

[0022] In summary, the forging method and forging provided by the present invention have the following technical effects:

[0023] 1. The segmented heating process and inert gas protection for raw material pretreatment effectively avoid decarburization and overheating on the billet surface, ensuring the uniformity and stability of the billet structure;

[0024] 2. Through the forging machine and multi-directional forging process, precise control of metal deformation is achieved, which significantly improves the uniformity and refinement of the internal structure of the forging and enhances the comprehensive mechanical properties of the forging;

[0025] 3. The cooling curve set according to the characteristics of the forging can effectively control the residual stress inside the forging, avoid deformation and cracking of the forging, and improve the dimensional accuracy and stability of the forging;

[0026] 4. The post-forging treatment process combining shot peening and grinding finishing further optimizes the internal structure and surface properties of the forgings, achieving a better balance in strength, toughness, fatigue life and surface quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Flowchart of an embodiment of the present invention. DETAILED DESCRIPTION

[0028] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described and discussed below in conjunction with the drawings of the present invention. Obviously, what is described here is only a part of the examples of the present invention, not all the examples. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] To facilitate understanding of the embodiments of the present invention, the following will be further explained with reference to specific embodiments as examples in conjunction with the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] See Figure 1 The present invention discloses a forging method of forgings, comprising the following steps: S1, cutting qualified raw materials into forging blanks of required sizes, grinding the cut forging blanks to remove burrs and oxide layers on the cutting edges; S2, preheating the forging blanks at low temperatures, heating the forging blanks to 400-500°C, controlling the heating rate at 80-100°C / h, and keeping the temperature for 1-1.5 hours; S3, heating the forging blanks at high temperatures, heating the forging blanks to 1050-1150°C, adjusting the heating rate at 120-150°C / h, and keeping the temperature at this temperature for 2-3 hours to make the forging blanks fully austenitic. S4. Use a forging machine to perform multi-directional forging on the forging blank, and then perform upsetting and drawing treatment after multi-directional forging; S5. Transfer the forging to a cooling device for cooling, and accurately set the cooling curve according to the shape and size of the forging; S6. After cooling, the forging is heat treated by first heating the forging to 850-900℃ and keeping it warm for 1.5-2.5 hours, and then performing oil quenching treatment, and the quenching oil temperature is controlled at 40-60℃; after quenching, it is immediately tempered at a tempering temperature of 550-650℃, keeping it warm for 2-3 hours, and the number of tempering times is 2; S7. The forging after heat treatment is shot peened and ground.

[0033] Specifically, in step S1, the raw material is cut by laser cutting, and the deviation range between the forging blank after cutting and the design size is controlled within ±0.3mm, and the surface roughness Ra of the forging blank during grinding is less than 1.2μm. The laser cutting technology is mature and the cutting effect is better. In addition, the burrs and oxide layer on the cutting edge can be removed by grinding.

[0034] Specifically, during the heating process of step S2 and the heating process of step S3, an inert gas is used to prevent oxidation and decarburization of the forging blank surface. More specifically, the inert gas is argon.

[0035] Specifically, in step S4, multi-directional forging involves applying different forging forces sequentially along the X, Y, and Z axes of the forging blank. The ratio of the forging forces along the X, Y, and Z axes is pre-set based on the shape and performance requirements of the forging. Specifically, for axisymmetric forgings, the ratio of the forging forces in the X and Y axes can be set to 1:1, while the forging force in the Z axis is adjusted based on the ratio of the forging height to diameter. Multi-directional forging results in a more uniform and refined internal structure of the blank.

[0036] Wherein, in some embodiments, in step S5: when the forging is a shaft forging, wherein the length is less than 600mm and the diameter is less than 60mm for a small-size shaft forging, after forging is completed, the temperature is first rapidly cooled to 500-600°C at a rate of 120-150°C / min, and then slowly cooled to room temperature at a rate of 30-40°C / min; wherein the length is between 600mm-1200mm and the diameter is between 60mm-120mm for a medium-size shaft forging, after forging is completed, the temperature is first cooled to 550°C-650°C at a rate of 80-120°C / min, and then cooled to room temperature at a rate of 20-30°C / min; wherein the length is greater than 1200mm and the diameter is greater than 120mm For large-sized shaft forgings, slow cooling is adopted throughout the process after forging, and the cooling rate is controlled at 10-20℃ / min. Small-sized shaft forgings have a relatively large surface area, faster heat dissipation, and relatively small internal thermal stress, and can withstand a relatively fast initial cooling rate. Slow cooling in the later stage can avoid excessive tissue stress caused by excessive cooling and leading to cracks; the thermal conductivity characteristics of medium-sized shaft forgings are between small and large sizes. Such a cooling curve can balance thermal stress and tissue stress, prevent deformation and cracking, and ensure certain mechanical properties at the same time; large-sized shaft forgings have more internal heat accumulation, and excessive cooling will cause huge thermal stress, which is easy to cause cracks or even fractures. The use of slow cooling throughout the process can make the internal and external temperatures drop evenly, reducing stress concentration.

[0037] In some embodiments, in step S5: when the forging is a disc forging, the forging having a thickness of less than 50 mm is a thin disc forging, which is first air-cooled for 1-2 minutes after forging to reduce the surface temperature, then air-cooled to 500-600°C at a rate of 80-100°C / min, and finally slowly cooled to room temperature at a rate of 25-35°C / min; wherein, the forging having a thickness between 50 mm and 150 mm is a medium-thick disc forging, which is spray-cooled after forging to reduce the forging temperature to 600-700°C, the spray cooling rate is controlled at 60-80°C / min, and then slowly cooled to room temperature at a rate of 5-25°C / min. n speed to room temperature; among them, those with a thickness greater than 150mm are thick plate forgings, which are slowly cooled after forging, and the cooling rate is controlled at 8-15℃ / min. Thin plate forgings have a large surface area, and the initial cooling by air cooling can reduce the temperature difference between the surface and the core during subsequent air cooling. Air cooling can use its large surface area to quickly dissipate heat, and slow cooling in the later stage ensures uniformity of the structure; medium and thick plate forgings use spray cooling to quickly remove heat in the early stage, and it is more uniform than air cooling, and slow cooling in the later stage avoids excessive stress in the structure; the internal heat of thick plate forgings is not easy to dissipate, and slow cooling in the furnace can provide a more stable cooling environment, reducing the stress caused by excessive temperature gradient.

[0038] Wherein, in some embodiments, in step S5: when the forging is a complex shape forging, wherein the size is between 100mm-500mm, and the inner cavity diameter is less than 50mm or the boss height is less than 30mm, it is a small complex shape forging, after forging is completed, it is first cooled to 500-600℃ at a rate of 60-90℃ / min, and then slowly cooled to room temperature at a rate of 20-30℃ / min; wherein, the size is between 500mm-1000mm, and the inner cavity diameter is between 50mm-100mm or the boss height is between 30mm-60mm, it is a medium complex shape forging, after forging is completed, it is first naturally cooled in the air for 3-5 minutes, and then cooled to 550-650℃ at a rate of 40-70℃ / min, and finally cooled to room temperature at a rate of 20-30℃ / min. Slowly cool to room temperature at a rate of 15-25℃ / min; among them, large complex shape forgings with a size greater than 1000mm, an inner cavity diameter greater than 100mm or a boss height greater than 60mm, after forging, are first kept isothermally at 700-800℃ for 1-2 hours, then cooled to 300-400℃, and finally air-cooled to room temperature. Although small complex shape forgings have complex structures, their overall sizes are small and the heat dissipation is relatively fast. They are cooled moderately quickly in the early stage and slowly cooled in the later stage to balance the stress; medium-sized complex shape forgings are naturally cooled to initially balance the surface and internal temperatures, oil cooling can control the cooling rate and make the cooling relatively uniform, and slow cooling ensures the microstructure performance; large complex shape forgings have complex thermal stress and microstructure stress, and isothermal furnace cooling can make the internal structure evenly transformed, reducing the risk of stress concentration and deformation.

[0039] Among them, in step S7, the shot peening treatment uses steel shots with a shot diameter of 0.3-0.8 mm and a shot peening intensity of 0.25-0.4A; the grinding process uses a CNC grinder to reduce the surface roughness Ra of the forging to 0.8-1.6 μm, and a compressive stress layer is formed on the surface of the forging by shot peening to improve its fatigue resistance and surface hardness. The grinding process uses a high-precision CNC grinder to reduce the surface roughness Ra of the forging to 0.8-1.6 μm, ensuring that the dimensional accuracy and surface finish of the forging meet the high-precision assembly requirements.

[0040] A forging comprises the following components by mass percentage: carbon: 0.2-0.4%; nickel 1.5-2.5%; chromium 0.8-1.2%; molybdenum 0.15-0.25%; vanadium 0.05-0.15%; the balance being iron and trace impurity elements.

[0041] In Example 1 of the present invention, a shaft forging with a length of 800 mm and a diameter of 60 mm is forged with reference to the above-mentioned process. The forging is carried out using a new servo forging machine. Upsetting and drawing are performed after multi-directional forging. The upsetting ratio is 2.2, the drawing ratio is 3.2, the forging temperature is between 1020-1080°C, and a method of first rapid cooling and then slow cooling is adopted. The cooling rate is accurately controlled. After tempering and finishing, the tensile strength of the shaft forging reaches 900-1000 MPa, the yield strength reaches 700-800 MPa, the straightness error is controlled within ±0.05 mm, and the surface roughness Ra is 1.0 μm, which meets the use requirements of high-speed rotating shafts. The production cycle is shortened by 20% compared with the traditional process.

[0042] In Example 2 of the present invention, referring to the above process, a ring forging is forged with an outer diameter of 300 mm, an inner diameter of 200 mm, and a thickness of 40 mm. Suitable alloy steel blanks are selected and pre-treated. The cutting and grinding effects are good, and there are no abnormalities in the heating process. During forging, multi-directional forging allows the metal to flow evenly within the ring. The forging temperature is 1060°C. Subsequent upsetting and drawing operations are carried out according to the characteristics of the ring. Lubricants are used to reduce mold wear. Post-forging cooling is set according to the characteristics of the ring forging. After cooling, the ring forging is tempered and finished. The roundness error of the ring forging is controlled within ±0.03 mm, the difference in radial and axial hardness is less than HB20, and it exhibits good stability when subjected to radial pressure and torque, meeting the requirements of ring parts in high-precision mechanical transmission. The mold service life is increased by 30% compared to traditional processes.

[0043] In summary, the forging method and forging provided by the present invention have the following technical effects:

[0044] 1. The segmented heating process and inert gas protection of raw material pretreatment effectively avoid decarburization and overheating of the billet surface, ensuring the uniformity and stability of the billet structure;

[0045] 2. Through the forging machine and multi-directional forging process, precise control of metal deformation is achieved, which significantly improves the uniformity and refinement of the internal structure of the forging and enhances the comprehensive mechanical properties of the forging;

[0046] 3. The cooling curve set according to the characteristics of the forging can effectively control the residual stress inside the forging, avoid deformation and cracking of the forging, and improve the dimensional accuracy and stability of the forging;

[0047] 4. The post-forging treatment process combining shot peening and grinding finishing further optimizes the internal structure and surface properties of the forgings, achieving a better balance in strength, toughness, fatigue life and surface quality.

[0048] The technical means disclosed in the solutions of the present invention are not limited to those disclosed in the above-mentioned embodiments, but also include technical solutions composed of any combination of the above-mentioned technical features. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A forging method for a forging, characterized in that: The steps include: S1. Cut qualified raw materials into forging blanks of required sizes, and grind the cut forging blanks to remove burrs and oxide layers on the cutting edges; S2. Preheat the forging blank at low temperature, heat the forging blank to 400-500℃, control the heating rate at 80-100℃ / h, and keep it warm for 1-1.5 hours; S3. Heat the forging blank to 1050-1150°C at a heating rate of 120-150°C / h and keep it at this temperature for 2-3 hours to fully austenitize the forging blank. S4. Use a forging machine to perform multi-directional forging on the forging blank, and then perform upsetting and drawing treatment after multi-directional forging; S5. Transfer the forging to a cooling device for cooling, and accurately set the cooling curve according to the shape and size of the forging; S6. After cooling, the forgings are heat treated by first heating them to 850-900°C and keeping them warm for 1.5-2.5 hours, then oil quenching them with the quenching oil temperature controlled at 40-60°C; tempering is immediately performed after quenching at a tempering temperature of 550-650°C and keeping them warm for 2-3 hours, with the tempering number of times being 2 times; S7. Shot peening and grinding are performed on the heat-treated forgings.

2. A forging method for a forging according to claim 1, characterized in that: In step S1, the raw material is cut by laser cutting, and the deviation range between the cut forging blank and the design size is controlled within ±0.3 mm, and the surface roughness Ra of the forging blank during the grinding process is less than 1.2 μm.

3. The forging method of a forging according to claim 1, characterized in that: During the heating process of step S2 and the heating process of step S3, an inert gas is used to prevent oxidation and decarburization of the surface of the forging blank.

4. The forging method of a forging according to claim 1, characterized in that: In step S4, multi-directional forging is to apply different forging forces in sequence along the X-axis, Y-axis and Z-axis of the forging blank. The ratio of the forging forces in the X-axis, Y-axis and Z-axis is pre-set according to the shape and performance requirements of the forging.

5. The forging method of a forging according to claim 1, characterized in that: In step S5: When the forging is a shaft forging, Among them, small-sized shaft forgings with a length of less than 600mm and a diameter of less than 60mm are forged. After forging, the temperature is first rapidly cooled to 500-600℃ at a rate of 120-150℃ / min, and then slowly cooled to room temperature at a rate of 30-40℃ / min. Among them, medium-sized shaft forgings with a length between 600mm-1200mm and a diameter between 60mm-120mm are cooled to 550℃-650℃ at a rate of 80-120℃ / min after forging, and then cooled to room temperature at a rate of 20-30℃ / min. Among them, large-size shaft forgings have a length greater than 1200mm and a diameter greater than 120mm. After forging, they are subjected to full-process slow cooling, with the cooling rate controlled at 10-20℃ / min.

6. The forging method of a forging according to claim 1, characterized in that: In step S5: When the forging is a disc forging, Among them, thin disc forgings with a thickness of less than 50mm are air-cooled for 1-2 minutes after forging to reduce the surface temperature, then air-cooled to 500-600℃ at a speed of 80-100℃ / min, and finally slowly cooled to room temperature at a speed of 25-35℃ / min; Among them, medium-thick plate forgings with a thickness between 50mm and 150mm are forged. After forging, spray cooling is used to reduce the forging temperature to 600-700℃. The spray cooling rate is controlled at 60-80℃ / min, and then slowly cooled to room temperature at a rate of 5-25℃ / min. Among them, those with a thickness greater than 150mm are thick plate forgings, which are slowly cooled after forging, with the cooling rate controlled at 8-15℃ / min.

7. The forging method of a forging according to claim 1, characterized in that: In step S5: When the forging is a complex shape forging, Among them, the size is between 100mm-500mm, and its inner cavity diameter is less than 50mm or its boss height is less than 30mm. It is a small complex shape forging. After forging, it is first cooled to 500-600℃ at a rate of 60-90℃ / min, and then slowly cooled to room temperature at a rate of 20-30℃ / min. Among them, medium-sized complex-shaped forgings with a size between 500mm-1000mm, an inner cavity diameter between 50mm-100mm, or a boss height between 30mm-60mm are first naturally cooled in air for 3-5 minutes after forging, then cooled to 550-650℃ at a rate of 40-70℃ / min, and finally slowly cooled to room temperature at a rate of 15-25℃ / min; Among them, large complex-shaped forgings are those with a size greater than 1000mm, an inner cavity diameter greater than 100mm, or a boss height greater than 60mm. After forging, they are first kept isothermally at 700-800℃ for 1-2 hours, then cooled to 300-400℃, and finally air-cooled to room temperature.

8. A forging method and forging according to claim 7, characterized in that: In step S7, the shot peening treatment uses steel shots with a shot diameter of 0.3-0.8 mm and a shot peening intensity of 0.25-0.4A; the grinding process uses a CNC grinder to reduce the surface roughness Ra of the forging to 0.8-1.6 μm.

9. A forging, produced by the forging method according to any one of claims 1 to 8, comprising the following components, counted by mass percentage: Carbon: 0.2-0.4%; Nickel 1.5-2.5%; Chromium 0.8-1.2%; Molybdenum 0.15-0.25%; Vanadium 0.05-0.15%; The balance is iron and trace impurity elements.

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