High-quality and high-uniformity large H-shaped ring forging and production method thereof

Abstract

The invention relates to the technical field of ring forging production, in particular to a high-quality and high-uniformity large H-shaped ring forging and a production method thereof. The production method comprises the steps that normalizing treatment, primary tempering treatment, rough machining before hardening and tempering, quenching treatment, secondary tempering treatment, primary stress relief annealing, rough machining, secondary stress relief annealing and finish machining are sequentially carried out on the large H-shaped ring forging. The large H-shaped ring forging has good strength, hardness and uniformity, and it is guaranteed that the service life meets the expectation.

Description

Technical Field

[0001] The invention relates to the technical field of ring forging production, and in particular to a high-quality, high-uniformity large-scale H-shaped ring forging and a production method thereof. Background Art

[0002] Ring forgings with special cross-sections are widely used in many fields due to their unique shape and superior performance. For example, they can be used to manufacture aircraft engine parts, landing gear and other key components for the aerospace field, and can be used as replacement ring forgings for large marine hydraulic pile hammers to improve the overall performance and reliability of equipment. In the manufacture of transportation vehicles such as rails, special-section ring forgings can be used to manufacture various connectors, supports, etc.

[0003] The upper and lower surfaces of the H-shaped ring forging are provided with annular grooves, and the H-shaped cross section is named after it. The use environment of large H-shaped ring forgings is relatively harsh. Not only do they bear the pressure and friction from the equipment, but they also need to maintain stability and uniformity during the force and movement process. Therefore, the processing accuracy, strength and hardness requirements of large H-shaped ring forgings are relatively high.

[0004] In order to obtain high-quality and high-performance H-shaped ring forgings, Chinese invention patent application CN106238632A discloses a method for rolling forming H-shaped cross-section rings. By accurately designing the blank size of the ring, the roller feed speed and rotation speed during the ring rolling process must be strictly controlled to accurately control the performance of the ring. This method uses the principle of constant volume during the rolling process to roll the H-shaped cross section, and forms a fibrous structure in the material through the forming process, thereby improving the mechanical properties and comprehensive properties of the material. However, this method does not study the changes in material strength, hardness, etc. of the H-shaped ring forging during the heat treatment process. Summary of the invention

[0005] In view of the problem that the prior art lacks a heat treatment method to improve the strength, hardness and uniformity of H-ring forgings, the present invention provides a high-quality, high-uniformity large-scale H-ring forging and a production method thereof. The obtained large-scale H-ring forging has good strength, hardness and uniformity, ensuring that its service life meets expectations.

[0006] In a first aspect, the present invention provides a method for producing a large H-shaped ring forging with high quality and high uniformity, comprising the steps of sequentially performing normalizing treatment, primary tempering treatment, rough machining before quenching and tempering, quenching treatment, secondary tempering treatment, primary stress relief annealing, rough machining, secondary stress relief annealing, and finishing on the large H-shaped ring forging, wherein: The chemical composition of the large H-ring forging includes, by weight percentage, C 0.38%~0.43%, Si 0.17%~0.37%, Mn 0.60%~0.80%, Cr 0.70%~0.90%, Mo 0.20%~0.30%, Ni 1.65%~2.00%, Cu≤0.20%, P≤0.015%, S≤0.010%, [N]≤100ppm, [O]≤20ppm, [H]≤2.0ppm, and the rest is Fe and unavoidable impurities; The normalizing process is as follows: a1. Place the large H-ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, raise the temperature to 350℃±10℃, and keep it warm for 4~6h; a2. After the insulation is completed, heat up to 650℃±10℃ at a rate of ≤80℃ / h and keep it for 4~6h; a3. After the insulation is completed, the temperature is raised to 860~890℃ at a rate of ≤150℃ / h, and three insulations are carried out at 30~55mm / h according to the height of the large H-ring forging; a4. After three heat preservations, take the furnace out and implement air cooling; The primary tempering process is as follows: b1. Place the large H-ring forging into a heat treatment furnace with a temperature of ≤350℃, heat it to 660~700℃ at a rate of ≤80℃ / h, and keep it at this temperature for 15~18h; b2. After the insulation is completed, the furnace is cooled to ≤350℃ at a rate of ≤20℃ / h and then air-cooled; The quenching process is as follows: c1. Place the large H-ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, raise the temperature to 350℃±10℃, and keep it warm for 4~6h; c2. After the insulation is completed, heat up to 650℃±10℃ at a rate of ≤80℃ / h and keep it warm for 4~6h; c3. After the insulation is completed, the temperature is rapidly raised to 840~870℃ at ≤150℃ / h, and three insulations are carried out at 40~60mm / h according to the effective thickness of the large H-ring forging; c4. After the three insulations, the forging is taken out of the furnace and quenched. According to the effective thickness of the large H-ring forging, the quenching time is 0.6~1.2s / mm; The secondary tempering process is as follows: d1. Place the H-ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, heat it to 300~350℃ at a rate of ≤80℃ / h, and keep it warm for 3~4h; d2. After the insulation is completed, the temperature is raised to 550~590℃ at a rate of ≤60℃ / h, and secondary insulation is carried out at 30~40mm / h according to the effective height of the web position of the H-ring forging; d3. After the second heat preservation, take the product out of the furnace and air cool it to room temperature.

[0007] Furthermore, the cooling medium for quenching treatment is water at 25-40°C, and the cooling medium is first kept in a stable forced convection state, and then kept in a natural convection state; preferably, the cooling medium is kept in a stable forced convection state within the first 6 minutes of cooling.

[0008] Furthermore, during the quenching treatment, the large H-shaped ring forging maintains an inclination of 10°~15° during the water entry and exit stages, and two cranes are continuously raised and lowered alternately in the water to ensure that water flows in the upper groove of the large H-shaped ring forging.

[0009] Further, the stress relief annealing process is as follows: e1. Place the large H-ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, raise the temperature to 350℃±10℃, and keep it warm for 3~6h; e2. After the insulation is completed, heat up to 500~550℃ at a rate of ≤60℃ / h and keep it for 5~8h; e3. After the insulation is completed, cool the furnace to ≤350℃ at ≤20℃ / h; e4. After the furnace cooling is completed, take the product out of the furnace and air cool it to room temperature.

[0010] Further, the secondary stress relief annealing process is as follows: g1. Place the large H-ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, raise the temperature to 350℃±10℃, and keep it warm for 3~6h; g2. After the insulation is completed, heat up to 480~530℃ at a rate of ≤60℃ / h and keep it warm for 5~8h; g3. After the insulation is completed, cool the furnace to ≤300℃ at ≤20℃ / h; g4. After the furnace cooling is completed, take the product out of the furnace and air cool it to room temperature.

[0011] Furthermore, the large H-shaped ring forging is forged through the steps of blanking, rounding, removing the water riser, primary upsetting, drawing, secondary upsetting, punching, expanding and ring rolling to the forging size, and the total forging ratio is controlled to be not less than 10:1, and the total upsetting ratio is not less than 6:1, which can effectively ensure the density of the internal structure of the large H-shaped ring forging.

[0012] Furthermore, the surface hardness is tested after the primary stress relief annealing and the secondary stress relief annealing, and the method is as follows: (1) Roughly grind the surface of the selected large H-ring forging, control the rough grinding depth to 2mm, the grinding area is larger than 50mm*50mm, and ensure that the grinding area is flat and has no depressions; (2) Finely grind and polish the coarsely ground parts, with a polishing depth of ≤1mm, and ensure that the polished parts are flat and free of depressions, and the surface roughness Ra ≤7μm; (3) Perform hardness test on the finely ground and polished parts, and take the average value of each part after 3 tests.

[0013] Furthermore, step (1) specifically includes selecting one location at every 60° interval on the outer diameter surface, inner diameter surface, upper groove surface, and lower groove surface of the selected large H-shaped ring forging, for a total of 24 locations for rough grinding.

[0014] Furthermore, the large H-ring forging after fine machining was sawn into sections to obtain test blocks, which were then decomposed and samples were taken at 1 / 3 and 1 / 2 of the web for testing.

[0015] In a second aspect, the present invention provides a large H-shaped ring forging produced by the above production method, which meets the requirements of hardness of 31~32HRC, yield strength ≥700Mpa, elongation after fracture ≥12%, and room temperature impact energy Aku ≥45J.

[0016] Furthermore, the outer diameter of the large H-ring forging is 10000~12000mm, the inner diameter is 8000~9500mm, and the height is 100~400mm.

[0017] The beneficial effects of the present invention are: The alloy steel material adopted in the present invention is more conducive to the realization of high strength, hardness and uniform performance of large H-shaped ring forgings after heat treatment. By reasonably designing quenching and tempering parameters, the surface hardness of large H-shaped ring forgings after quenching and tempering is controlled within the range of 31-32HRC. Through actual production verification, a good match between strength and plasticity and toughness is achieved, thereby ensuring that the service life of large H-shaped ring forgings reaches a high level. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a schematic diagram of the cross-sectional structure of a large H-ring forging. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. 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 should fall within the scope of protection of the present invention.

[0021] Example 1 A large H-shaped ring forging with an outer diameter of 10220 mm, an inner diameter of 9198 mm, and a height of 390 mm is prepared according to the following preparation method: (1) According to the product size, shape and weight, the process design is carried out. According to the design plan, 98 tons of die-cast steel ingot raw materials are selected for re-testing. Its chemical composition meets C 0.38%, Si 0.17wt%, Mn 0.60wt%, Cr 0.90wt%, Mo0.30wt%, Ni 2.00wt%, Cu 0.10wt%, P 0.005wt%, S 0.005wt%, [N] 10ppm, [O] 20ppm, [H] 2.0ppm, and the rest is Fe and unavoidable impurities. The raw materials are cut into pieces and the forging is completed through the steps of rolling, removing the water riser, upsetting, drawing, upsetting, punching, expanding and ring rolling to the forging size. The total forging ratio is controlled to be 10:1 and the total upsetting ratio is 6:1.

[0022] (2) Heat treatment and performance testing of large H-ring forgings are carried out in the following steps: a. Normalizing treatment is performed on large H-ring forgings. The process is as follows: a1. Place the large H-ring forging into a heat treatment furnace at 300°C, heat it to 340°C, and keep it at that temperature for 6 hours; a2. After the insulation is completed, the temperature is raised to 640℃ at a rate of 50℃ / h and kept at this temperature for 6h; a3. After the insulation is completed, the temperature is raised to 860°C at a rate of 110°C / h, and three insulations are performed at 39mm / h according to the height of the large H-ring forging; a4. After three insulation cycles, take the furnace out of the oven and air cool.

[0023] b. Perform a tempering treatment on the large H-ring forgings after normalizing. The process is as follows: b1. Place the large H-ring forging into a heat treatment furnace at 300°C, heat it to 660°C at a rate of 60°C / h, and keep it at that temperature for 18h; b2. After the insulation is completed, cool the furnace to 300℃ at a rate of 18℃ / h, then take it out of the furnace and implement air cooling.

[0024] c. The large H-shaped ring forgings after the first tempering are rough-machined before quenching and tempering to produce an H-shape, and the machining allowances of each part after quenching and tempering are kept close as much as possible, and then the overall quenching treatment is carried out. The process is as follows: c1. Place the large H-ring forging into a heat treatment furnace at 300°C, heat it to 340°C, and keep it at that temperature for 6 hours; c2. After the insulation is completed, the temperature is raised to 640°C at a rate of 50°C / h and maintained for 6h; c3. After the insulation is completed, the temperature is rapidly raised to 860°C at 110°C / h, and three insulations are performed at 60mm / h according to the effective thickness of the large H-ring forging; c4. After three insulation cycles, take the forging out of the furnace and use two cranes and special tooling for H-ring forgings to carry out quenching and cooling. The cooling medium is 27°C water. The large H-ring forgings are tilted at 15° during the water entry and exit stages. The cooling medium is kept in a stable forced convection state for the first 6 minutes, and then kept in a natural convection state. During the quenching and cooling process, the two cranes are continuously raised and lowered alternately in the water to ensure that the water flows in the upper groove of the large H-ring forgings. According to the effective thickness of the large H-ring forgings, the quenching and cooling time is 1.2s / mm.

[0025] d. The large H-ring forgings after quenching are subjected to overall secondary tempering treatment, the process includes: d1. Place the large H-ring forging into a heat treatment furnace at 300°C, heat it to 340°C at a rate of 80°C / h, and keep it at that temperature for 3h; d2. After the insulation is completed, the temperature is raised to 560°C at a rate of 55°C / h, and secondary insulation is performed at 30mm / h according to the effective thickness of the H-ring forging; d3. After the second heat preservation, take the product out of the furnace and air cool it to room temperature.

[0026] e. The large H-shaped ring forgings which have been subjected to overall secondary tempering treatment are subjected to overall primary stress relief annealing treatment. The process is as follows: e1. Place the large H-ring forging into a heat treatment furnace at 300°C, raise the temperature to 340°C, and keep it at that temperature for 6 hours; e2. After the insulation is completed, the temperature is raised to 550°C at a rate of 60°C / h and maintained for 5h; e3. After the insulation is completed, the furnace is cooled to 300℃ at 20℃ / h; e4. After the furnace cooling is completed, take the product out of the furnace and air cool it to room temperature.

[0027] f. Rough machining of large H-shaped ring forgings that have completed stress relief annealing treatment. The machining amount of each surface of the H-shaped ring forging should be 5mm~8mm. Then, surface hardness testing is carried out. The method is as follows: f1. Rough grinding is performed at 24 locations, one at every 60°, on the outer diameter surface, inner diameter surface, upper groove surface, and lower groove surface of the selected large H-shaped ring forging. The depth of rough grinding is controlled at 2mm, the grinding area is larger than 50mm*50mm, and the grinding area is ensured to be flat and without depressions; f2. Finely grind and polish the coarsely ground parts, with a polishing depth of ≤1mm, and ensure that the polished parts are flat and without depressions, and the surface roughness Ra≤7μm; f3. Perform hardness test on fine grinding and polishing parts, test each part 3 times and take the average value, the surface hardness is 32~33.1HRC.

[0028] g. For the large H-ring forgings that have been rough-machined, the overall secondary stress relief annealing treatment is carried out. The process is as follows: g1. Place the large H-ring forging into a heat treatment furnace at 300°C, heat it to 340°C, and keep it at that temperature for 6 hours; g2. After the insulation is completed, the temperature is raised to 520°C at a rate of 60°C / h and maintained for 5h; g3. After the insulation is completed, cool the furnace to 300℃ at 10℃ / h; g4. After the furnace cooling is completed, take the product out of the furnace and air cool it to room temperature.

[0029] h. Rough machining of large H-shaped ring forgings that have completed secondary stress relief annealing treatment. The machining amount of each surface of the H-shaped ring forging should be 4mm~6mm. Then, surface hardness testing is carried out. The method is as follows: h1. Rough grinding is performed at 24 locations, one at every 60°, on the outer diameter surface, inner diameter surface, upper groove surface, and lower groove surface of the selected large H-shaped ring forging. The depth of rough grinding is controlled at 2mm, the grinding area is larger than 50mm*50mm, and the grinding area is ensured to be flat and without depressions; h2. Finely grind and polish the coarsely ground parts, with a polishing depth of ≤1mm, and ensure that the polished parts are flat and without depressions, and the surface roughness Ra≤7μm; h3. Perform hardness test on fine grinding and polishing parts, test each part 3 times and take the average value, the surface hardness is 31~32HRC.

[0030] i The large H-ring forgings that have completed the secondary stress relief annealing treatment are finely machined to the delivery size, and then the H-ring forgings are segmented using a sawing machine to obtain test blocks with a length of about 320 mm. The test blocks are decomposed and samples are taken at 1 / 3 and 1 / 2 of the web for testing. The results are shown in Table 1 below.

[0031] Table 1 Mechanical properties of large H-ring forgings of Example 1

[0032] Example 2 A large H-shaped ring forging with an outer diameter of 11618 mm, an inner diameter of 8101 mm, and a height of 130 mm is prepared according to the following preparation method: (1) According to the product size, shape and weight, the process design is carried out. According to the design plan, 100 tons of die-cast steel ingot raw materials are selected for re-testing. Its chemical composition meets C 0.43%, Si 0.37wt%, Mn 0.80wt%, Cr 0.70wt%, Mo0.20wt%, Ni 1.65wt%, Cu 0.20wt%, P 0.010wt%, S 0.008wt%, [N] 20ppm, [O] 10ppm, [H] 1.0ppm, and the rest is Fe and unavoidable impurities. The raw materials are cut and the forging is completed through the steps of rolling, removing the water riser, upsetting, drawing, upsetting, punching, expanding and ring rolling to the forging size. The total forging ratio is controlled to be 10:1 and the total upsetting ratio is 6:1.

[0033] (2) Heat treatment and performance testing of large H-ring forgings are carried out in the following steps: a. Normalizing treatment is performed on large H-ring forgings. The process is as follows: a1. Place the large H-ring forging into a heat treatment furnace at 280°C, heat it to 360°C, and keep it at that temperature for 4 hours; a2. After the insulation is completed, the temperature is raised to 660°C at a rate of 80°C / h and maintained for 4 hours; a3. After the insulation is completed, the temperature is raised to 890℃ at a rate of 150℃ / h, and three insulations are carried out at 55mm / h according to the height of the large H-ring forging; a4. After three insulation cycles, take the furnace out of the oven and air cool.

[0034] b. Perform a tempering treatment on the large H-ring forgings after normalizing. The process is as follows: b1. Place the large H-ring forging into a heat treatment furnace at 280°C, heat it to 700°C at a rate of 70°C / h, and keep it at that temperature for 15h; b2. After the insulation is completed, cool the furnace to 280℃ at a rate of 12℃ / h and then air cool.

[0035] c. The large H-shaped ring forgings after the first tempering are rough-machined before quenching and tempering to produce an H-shape, and the machining allowances of each part after quenching and tempering are kept close as much as possible, and then the overall quenching treatment is carried out. The process is as follows: c1. Place the large H-ring forging into a heat treatment furnace at 280°C, heat it to 360°C, and keep it at that temperature for 4 hours; c2. After the insulation is completed, the temperature is raised to 660°C at a rate of 80°C / h and maintained for 4h; c3. After the insulation is completed, the temperature is rapidly raised to 840°C at 150°C / h, and three insulations are performed at 40mm / h according to the effective thickness of the large H-ring forging; c4. After three insulation cycles, take the forging out of the furnace and use two cranes and special tooling for H-ring forgings to carry out quenching and cooling. The cooling medium is 38°C water. The large H-ring forgings are tilted at 10° during the water entry and exit stages. The cooling medium is kept in a stable forced convection state for the first 6 minutes, and then kept in a natural convection state. During the quenching and cooling process, the two cranes are alternately raised and lowered in the water to ensure that the water flows in the upper groove of the large H-ring forgings. According to the effective thickness of the large H-ring forgings, the quenching and cooling time is 0.6s / mm.

[0036] d. The large H-ring forgings after quenching are subjected to overall secondary tempering treatment, the process includes: d1. Place the large H-ring forging into a heat treatment furnace at 280°C, heat it to 300°C at a rate of 20°C / h, and keep it at that temperature for 4h; d2. After the insulation is completed, the temperature is raised to 590°C at a rate of 40°C / h, and secondary insulation is performed at 40mm / h according to the effective thickness of the H-ring forging; d3. After the second heat preservation, take the product out of the furnace and air cool it to room temperature.

[0037] e. The large H-shaped ring forgings which have been subjected to overall secondary tempering treatment are subjected to overall primary stress relief annealing treatment. The process is as follows: e1. Place the large H-ring forging into a heat treatment furnace at 280°C, heat it to 360°C, and keep it at that temperature for 3 hours; e2. After the insulation is completed, the temperature is raised to 500°C at a rate of 40°C / h and maintained for 8h; e3. After the insulation is completed, cool the furnace to 280℃ at 15℃ / h; e4. After the furnace cooling is completed, take the product out of the furnace and air cool it to room temperature.

[0038] f. Rough machining of large H-shaped ring forgings that have completed stress relief annealing treatment. The machining amount of each surface of the H-shaped ring forging should be 5mm~8mm. Then, surface hardness testing is carried out. The method is as follows: f1. Rough grinding is performed at 24 locations, one at every 60°, on the outer diameter surface, inner diameter surface, upper groove surface, and lower groove surface of the selected large H-shaped ring forging. The depth of rough grinding is controlled at 2mm, the grinding area is larger than 50mm*50mm, and the grinding area is ensured to be flat and without depressions; f2. Finely grind and polish the coarsely ground parts, with a polishing depth of ≤1mm, and ensure that the polished parts are flat and without depressions, and the surface roughness Ra≤7μm; f3. Perform hardness test on fine grinding and polishing parts, test each part 3 times and take the average value, the surface hardness is 31.8~33.5HRC.

[0039] g. For the large H-ring forgings that have been rough-machined, the overall secondary stress relief annealing treatment is carried out. The process is as follows: g1. Place the large H-ring forging into a heat treatment furnace at 280°C, heat it to 360°C, and keep it warm for 3 hours; g2. After the insulation is completed, the temperature is raised to 480°C at a rate of 40°C / h and maintained for 8h; g3. After the insulation is completed, cool the furnace to 280℃ at 20℃ / h; g4. After the furnace cooling is completed, take the product out of the furnace and air cool it to room temperature.

[0040] h. Rough machining of large H-shaped ring forgings that have completed secondary stress relief annealing treatment. The machining amount of each surface of the H-shaped ring forging should be 4mm~6mm. Then, surface hardness testing is carried out. The method is as follows: h1. Rough grinding is performed at 24 locations, one at every 60°, on the outer diameter surface, inner diameter surface, upper groove surface, and lower groove surface of the selected large H-shaped ring forging. The depth of rough grinding is controlled at 2mm, the grinding area is larger than 50mm*50mm, and the grinding area is ensured to be flat and without depressions; h2. Finely grind and polish the coarsely ground parts, with a polishing depth of ≤1mm, and ensure that the polished parts are flat and without depressions, and the surface roughness Ra≤7μm; h3. Perform hardness test on fine grinding and polishing parts, test each part 3 times and take the average value, the surface hardness is measured to be 30.5~32.1HRC.

[0041] i The large H-ring forgings that have completed the secondary stress relief annealing treatment are finely machined to the delivery size, and then the H-ring forgings are segmented using a sawing machine to obtain test blocks with a length of about 320 mm. The test blocks are decomposed and samples are taken at 1 / 3 and 1 / 2 of the web for testing. The results are shown in Table 2 below.

[0042] Table 2 Mechanical properties of large H-ring forgings of Example 2

[0043] It can be seen from the test results of Example 1 and Example 2 that the various performance indicators and uniformity of the two large H-shaped ring forgings with different specifications and alloy compositions prepared by the production method of the present invention meet the use requirements.

[0044] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A method for producing large H-ring forgings with high quality and high uniformity, characterized in that: The method comprises the steps of sequentially performing normalizing treatment, primary tempering treatment, rough machining before quenching and tempering, quenching treatment, secondary tempering treatment, primary stress relief annealing, rough machining, secondary stress relief annealing, and finishing on a large H-shaped ring forging, wherein: In terms of weight percentage, the chemical composition of the large H-ring forging includes C 0.38%~0.43%, Si 0.17%~0.37%, Mn0.60%~0.80%, Cr 0.70%~0.90%, Mo 0.20%~0.30%, Ni 1.65%~2.00%, Cu≤0.20%, P≤0.015%, S≤0.010%, [N]≤100ppm, [O]≤20ppm, [H]≤2.0ppm, and the rest is Fe and unavoidable impurities; The normalizing process is as follows: a1. Place the large H-shaped ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, heat it to 350℃±10℃, and keep it warm for 4~6h; a2. After the insulation is completed, heat it to 650℃±10℃ at a rate of ≤80℃ / h, and keep it warm for 4~6h; a3. After the insulation is completed, heat it to 860~890℃ at a rate of ≤150℃ / h, and carry out three insulations at 30~55mm / h according to the height of the large H-shaped ring forging; a4. After the three insulations are completed, take it out of the furnace and implement air cooling; The primary tempering process is as follows: b1. Place the large H-shaped ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, heat it to 660~700℃ at a rate of ≤80℃ / h, and keep it warm for 15~18h; b2. After the insulation is completed, cool it to ≤350℃ at a rate of ≤20℃ / h, take it out of the furnace, and implement air cooling; The quenching process is as follows: c1. Place the large H-shaped ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, heat it to 350℃±10℃, and keep it warm for 4~6h; c2. After the insulation is completed, heat it to 650℃±10℃ at a rate of ≤80℃ / h, and keep it warm for 4~6h; c3. After the insulation is completed, quickly heat it to 840~870℃ at a rate of ≤150℃ / h, and carry out three insulations at 40~60mm / h according to the effective thickness of the large H-shaped ring forging; c4. After the three insulations are completed, take it out of the furnace and carry out quenching cooling. According to the effective thickness of the large H-shaped ring forging, the quenching cooling time is 0.6~1.2s / mm; The secondary tempering process is as follows: d1. Place the H-ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, heat it to 300~350℃ at a rate of ≤80℃ / h, and keep it warm for 3~4h; d2. After the insulation is completed, heat it to 550~590℃ at a rate of ≤60℃ / h, and implement secondary insulation at 30~40mm / h according to the effective thickness of the web position of the H-ring forging; d3. After the secondary insulation is completed, take it out of the furnace and air cool it to room temperature.

2. The production method according to claim 1, characterized in that The cooling medium for quenching treatment is water at 25~40℃. First, keep the cooling medium in a stable forced convection state, and then keep the cooling medium in a natural convection state.

3. The production method according to claim 2, characterized in that During the quenching treatment, the large H-shaped ring forging maintains an inclination of 10°~15° during the water entry and exit stages, and the crane is continuously raised and lowered alternately in the water to ensure that water flows in the upper groove of the large H-shaped ring forging.

4. The production method according to claim 1, characterized in that The primary stress relief annealing process is as follows: e1. Place the large H-ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, raise the temperature to 350℃±10℃, and keep it warm for 3~6h; e2. After the insulation is completed, heat up to 500~550℃ at a rate of ≤60℃ / h and keep it for 5~8h; e3. After the insulation is completed, cool the furnace to ≤350℃ at ≤20℃ / h; e4. After the furnace cooling is completed, take the product out of the furnace and air cool it to room temperature.

5. The production method according to claim 1, characterized in that The secondary stress relief annealing process is as follows: g1. Place the large H-ring forging into a heat treatment furnace with a furnace temperature of ≤350℃, raise the temperature to 350℃±10℃, and keep it warm for 3~6h; g2. After the insulation is completed, heat up to 480~530℃ at a rate of ≤60℃ / h and keep it warm for 5~8h; g3. After the insulation is completed, cool the furnace to ≤300℃ at ≤20℃ / h; g4. After the furnace cooling is completed, take the product out of the furnace and air cool it to room temperature.

6. The production method according to claim 1, characterized in that Large H-ring forgings are forged through the steps of blanking, rounding, removing water risers, primary upsetting, drawing, secondary upsetting, punching, expanding and ring rolling to the forging size. The total forging ratio is controlled to be no less than 10:1, and the total upsetting ratio is no less than 6:

1.

7. The production method according to claim 1, characterized in that The surface hardness is tested after the primary stress relief annealing and the secondary stress relief annealing as follows: (1) Roughly grind the surface of the selected large H-ring forging, control the rough grinding depth to 2mm, the grinding area is larger than 50mm*50mm, and ensure that the grinding area is flat and has no depressions; (2) Finely grind and polish the coarsely ground parts, with a polishing depth of ≤1mm, and ensure that the polished parts are flat and free of depressions, and the surface roughness Ra ≤7μm; (3) Perform hardness test on the finely ground and polished parts, and take the average value of each part after 3 tests.

8. The production method according to claim 1, characterized in that The large H-ring forgings after fine machining are sawn into sections to obtain test blocks, which are then decomposed and samples are taken from 1 / 3 and 1 / 2 of the web for testing.

9. A large H-shaped ring forging produced by the production method according to any one of claims 1 to 8, characterized in that: The hardness must be 31~32HRC, the yield strength must be ≥700Mpa, the elongation after fracture must be ≥12%, and the room temperature impact energy Aku must be ≥45J.

10. The large H-ring forging according to claim 9, characterized in that: The outer diameter is 10000~12000mm, the inner diameter is 8000~9500mm, and the height is 100~400mm.

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