Heat treatment method for medium-carbon bearing steel ring forgings with low residual stress
By optimizing the heat treatment process of medium carbon bearing steel ring forgings and controlling the cooling rate and temperature, the residual stress problem of medium carbon bearing steel ring forgings was solved, low residual stress production was achieved, the production cycle was shortened, energy consumption was reduced, and the risk of temper brittleness was avoided.
Patent Information
- Application Number
- CN202510812617.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-18
- Publication Date
- 2025-10-21
AI Technical Summary
The existing technology has residual stress problems when producing medium-carbon bearing steel ring forgings, resulting in long production cycles, high energy consumption and the risk of temper brittleness, which is particularly significant in the production of large bearing rings.
By controlling the chemical composition and dimensional characteristics of medium-carbon bearing steel ring forgings, combining tempering treatment, cooling methods and stress relief annealing methods, the heat treatment process is optimized, including tempering treatment, quenching cooling, tempering heat treatment and stress relief annealing, and the specific cooling rate and temperature are controlled to reduce residual stress.
It achieves the production of medium-carbon bearing steel ring forgings with low residual stress, shortens the production cycle, reduces energy consumption, avoids the risk of temper brittleness, and improves production efficiency and cost-effectiveness.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of thermal processing and relates to a heat treatment method for a medium-carbon bearing steel ring forging with low residual stress. Background Art
[0002] 42CrMo series ring forgings are often used to produce large bearing ring components. The residual stress in these materials significantly impacts the subsequent quenching process and precision manufacturing of the rings. In engineering, stress relief annealing is often added after the quenching and tempering heat treatment of ring forgings to reduce residual stress. Stress relief annealing involves heating the workpiece to a specific temperature, holding it for an extended period, and then slowly cooling it. The effectiveness of stress relief annealing is dependent on both the heating temperature and the holding time. The higher the heating temperature, the more complete the stress relief, requiring less holding time.
[0003] Although stress relief annealing after quenching and tempering of ring forgings can greatly improve the residual stress distribution of the material, it will increase the production cycle and energy consumption. Therefore, some ring forging manufacturers use a furnace cooling process after the tempering process of quenching and tempering, that is, combining tempering with stress relief annealing to shorten the production cycle and reduce production costs. For 42CrMo series medium-carbon bearing steel ring forgings, the tempering temperature is usually 600-650℃, and the material will be in the temperature range of 500-600℃ for a long time during the furnace cooling process, which will cause the material to have temper brittleness. As the size of ring forgings for bearing rings increases, elements such as Cr, Mn, and Ni are usually added to increase the hardenability of the material. These elements will increase the second type of temper brittleness of the material. In addition, ring forgings of different shapes and sizes have different sensitivities to cooling rates. Summary of the Invention
[0004] The present invention aims to provide a low residual stress heat treatment method associated with the chemical composition control and external dimension characteristics of medium carbon bearing steel ring forgings.
[0005] The present invention provides a heat treatment method for a medium-carbon bearing steel ring forging with low residual stress, comprising the following steps: Step 1: Perform quenching and tempering treatment on the ring forging; Step 2: Cool the ring forging after quenching and tempering; the specific method is as follows: When the chemical composition of the ring forging satisfies P+S+As+10×(Sn+Sb)>0.085 or Mn+Si+Cr+Ni>2.6, the cooling rate is set to 60℃ / h-120℃ / h and the cooling temperature is set to 400℃-450℃; Otherwise, the cooling rate of the ring forging is set to 40℃ / h-80℃ / h and the cooling temperature is set to 450℃-500℃; Step 3: Perform stress relief annealing on the cooled ring forging.
[0006] Furthermore, the specific process of quenching and tempering the ring forgings is as follows: S1.1. Heat the ring forging to 650℃±20℃ at a heating rate of ≤80℃ / h and keep it at this temperature for 1h-3h; S1.2. Heat to 860°C ± 10°C at a heating rate of ≤ 120°C / h and hold for 1.8 min / mm-2.2 min / mm; S1.3, quench and cool the ring forging; S1.4. Return to the furnace for tempering heat treatment.
[0007] Furthermore, the method for quenching and cooling the ring forging is as follows: Liquid-cool the ring forgings after heating and insulation in S1.2, and ensure that the temperature of the ring forgings after leaving the water is returned to 200℃±20℃.
[0008] Furthermore, the method for performing tempering heat treatment on the ring forging after quenching and cooling is as follows: Heat the ring forging to 620℃±30℃ at a rate of ≤50℃ / h and keep it warm for 2.2min / mm-2.5min / mm.
[0009] Furthermore, the method for performing stress relief annealing treatment on the cooled ring forging is as follows: The ring forging is heated to 530℃±30℃ at a heating rate of ≤40℃ / h and kept warm for 1.8min / mm-2.2min / mm; The furnace is cooled at a cooling rate of ≤40°C / h. When the temperature of the ring forging is below 300°C±50°C, the ring forging is taken out of the furnace and air-cooled.
[0010] Furthermore, the method for performing stress relief annealing treatment on the cooled ring forging is as follows: When the chemical composition of the ring forging meets P+S+As+10×(Sn+Sb)>0.085 or Mn+Si+Cr+Ni>2.6, the holding temperature is set to 500℃-530℃, otherwise the holding temperature is 530℃-560℃; When the effective thickness of the ring forging is ≤100mm or the shape is asymmetric, the furnace cooling temperature is set to 250℃-300℃, otherwise the furnace cooling temperature is 300℃-350℃.
[0011] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a low residual stress heat treatment method for medium carbon bearing steel ring forgings, which greatly reduces the residual stress of medium carbon bearing steel ring forgings by controlling the tempering heat treatment method, cooling method and stress relief annealing method of the ring forgings; and the present invention has the characteristics of short production cycle, low process cost, and no risk of temper brittleness of the ring forgings.
[0012] In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. DETAILED DESCRIPTION
[0013] In order to make the above-mentioned objects, features and advantages of the present invention more clear and easy to understand, the specific embodiments of the present invention are described in detail below.
[0014] The present invention provides a heat treatment method for a medium-carbon bearing steel ring forging with low residual stress, comprising the following steps: Step 1: Perform quenching and tempering treatment on the ring forging; the specific process is as follows: S1.1. Heat the ring forging to 650℃±20℃ at a heating rate of ≤80℃ / h and keep it at this temperature for 1h-3h; S1.2. Heat to 860°C ± 10°C at a heating rate of ≤ 120°C / h and hold for 1.8 min / mm-2.2 min / mm; S1.3, quench and cool the ring forging; S1.4. Return to the furnace for tempering heat treatment.
[0015] Step 2: Cool the ring forging after quenching and tempering; the specific method is as follows: When the chemical composition (w%) of the ring forging satisfies P+S+As+10×(Sn+Sb)>0.085 or Mn+Si+Cr+Ni>2.6, the cooling rate is set to 60℃ / h-120℃ / h and the cooling temperature is set to 400℃-450℃; Otherwise, the cooling rate of the ring forging is set to 40℃ / h-80℃ / h, and the cooling rate is set to 450℃-500℃; Step 3: Perform stress relief annealing on the cooled ring forging.
[0016] Preferably, the method for quenching and cooling the ring forging is: Liquid-cool the ring forgings after heating and insulation in S1.2, and ensure that the temperature of the ring forgings after leaving the water is returned to 200℃±20℃.
[0017] Preferably, the method for performing tempering heat treatment on the ring forging after quenching and cooling is: Heat the ring forging to 620℃±30℃ at a rate of ≤50℃ / h and keep it warm for 2.2min / mm-2.5min / mm.
[0018] Preferably, the method for performing stress relief annealing on the cooled ring forging is: The ring forging is heated to 530℃±30℃ at a heating rate of ≤40℃ / h and kept warm for 1.8min / mm-2.2min / mm; The furnace is cooled at a cooling rate of ≤40°C / h. When the temperature of the ring forging is below 300°C±50°C, the ring forging is taken out of the furnace and air-cooled.
[0019] In addition to the above methods, the method for stress relief annealing of the cooled ring forgings is: When the chemical composition of the ring forging meets P+S+As+10×(Sn+Sb)>0.085 or Mn+Si+Cr+Ni>2.6, the holding temperature is set to 500℃-530℃, otherwise the holding temperature is 530℃-560℃; When the effective thickness of the ring forging is ≤100mm or the shape is asymmetric, the furnace cooling temperature is set to 250℃-300℃, otherwise the furnace cooling temperature is 300℃-350℃.
[0020] Example 1: Taking the ring forging with chemical composition of C0.42, Si0.30, Mn0.85, Cr1.05, Ni0.40, P0.020, S0.020, As0.035, Sn0.01 and Sb0.01 as an example, the heat treatment method is as follows: The ring forgings are heated to 670°C at a heating rate of ≤80°C / h and held for 3 hours. Then, they are heated to 870°C at a heating rate of ≤120°C / h and held for 2.2 min / mm. After being liquid-cooled out of the furnace, the forgings are cooled to 220°C at the outlet water temperature, and then quenched and cooled. The forgings are then returned to the furnace for tempering heat treatment. The ring forgings are heated to 590°C at a heating rate of ≤50°C / h and held for 2.5 min / mm. The ring forgings are cooled to 400°C at a cooling rate of 120°C / h. The ring forgings are heated to 500°C at a heating rate of ≤40°C / h and kept warm for 1.8min / mm. They are then furnace cooled at a cooling rate of ≤40°C / h. When the temperature of the ring forgings is below 250°C, they are taken out of the furnace and air-cooled.
[0021] Example 2: Taking the ring forging with chemical composition of C0.42, Si0.30, Mn0.85, Cr1.05, Ni0.40, P0.012, S0.005, As0.015, Sn0.006 and Sb0.004 as an example, the heat treatment method is as follows: The ring forgings are heated to 630°C at a heating rate of 60°C / h, held at this temperature for 1 hour, then heated to 850°C at a heating rate of ≤100°C / h, held at this temperature for 1.8 min / mm, and then cooled to 180°C after leaving the furnace. The quenching is then stopped and the forgings are returned to the furnace for tempering heat treatment. The ring forgings are heated to 650°C at a heating rate of ≤50°C / h, held at this temperature for 2.2 min / mm; the ring forgings are cooled to 500°C at a cooling rate of 40°C / h. The ring forgings are heated to 560°C at a heating rate of ≤40°C / h and kept warm for 2.2 min / mm. They are then furnace cooled at a cooling rate of ≤20°C / h. When the temperature of the ring forgings is below 350°C, they are taken out of the furnace and air-cooled.
[0022] Example 3: Taking the ring forging with chemical composition of C0.42, Si0.15, Mn0.65, Cr0.95, Ni0.20, P0.022, S0.024, As0.04, Sn0.01 and Sb0.01 as an example, the heat treatment method is as follows: The ring forgings are heated to 650°C at a heating rate of ≤80°C / h, held for 2 hours, then heated to 860°C at a heating rate of ≤120°C / h, held for 2.0 min / mm, and then cooled to 200°C after exiting the furnace. The quenching is then stopped and the forgings are returned to the furnace for tempering heat treatment. The ring forgings are heated to 630°C at a heating rate of ≤50°C / h, held for 2.3 min / mm, and then cooled to 400°C at a cooling rate of 110°C / h. The ring forgings are heated to 510°C at a heating rate of ≤40°C / h and kept warm for 1.8 min / mm. They are then furnace cooled at a cooling rate of ≤40°C / h. When the temperature of the ring forgings is below 250°C, they are taken out of the furnace and air-cooled.
[0023] Example 4: Taking the ring forging with chemical composition of C0.42, Si0.15, Mn0.65, Cr0.95, Ni0.20, P0.012, S0.005, As0.015, Sn0.006 and Sb0.004 as an example, the heat treatment method is as follows: The ring forgings are heated to 650°C at a heating rate of 60°C / h and held for 2 hours. Then, they are heated to 860°C at a heating rate of ≤100°C / h and held for 1.8 min / mm. After being liquid-cooled out of the furnace, the quenching cooling is stopped when the water temperature of the forgings returns to 200°C. The ring forgings are then returned to the furnace for tempering heat treatment. The ring forgings are heated to 610°C at a heating rate of ≤50°C / h and held for 2.2 min / mm. The ring forgings are cooled to 500°C at a cooling rate of 40°C / h. The ring forgings are heated to 550°C at a heating rate of ≤40°C / h and kept warm for 2.2 min / mm. They are then furnace cooled at a cooling rate of ≤20°C / h. When the temperature of the ring forgings is below 350°C, they are taken out of the furnace and air-cooled.
[0024] Example 5: Taking the ring forging with chemical composition of C0.42, Si0.30, Mn0.85, Cr1.15, Ni0.60, P0.020, S0.020, As0.035, Sn0.01 and Sb0.01 as an example, the heat treatment method is as follows: The ring forgings are heated to 670°C at a heating rate of ≤80°C / h and held at this temperature for 3 hours. Then, they are heated to 870°C at a heating rate of ≤120°C / h and held at this temperature for 1.9 min / mm. After being liquid-cooled out of the furnace, the forgings are cooled to 220°C at the outlet water temperature, and then quenched and cooled. The forgings are then returned to the furnace for tempering heat treatment. The ring forgings are heated to 650°C at a heating rate of ≤50°C / h and held at this temperature for 2.4 min / mm. The ring forgings are cooled to 400°C at a cooling rate of 120°C / h. The ring forgings are heated to 500°C at a heating rate of ≤40°C / h and kept warm for 2.0min / mm. They are then furnace cooled at a cooling rate of ≤40°C / h. When the temperature of the ring forgings is below 250°C, they are taken out of the furnace and air-cooled.
[0025] Example 6: Taking the ring forging with chemical composition of C0.42, Si0.30, Mn0.85, Cr1.15, Ni0.60, P0.012, S0.005, As0.015, Sn0.006 and Sb0.004 as an example, the heat treatment method is as follows: The ring forgings are heated to 650°C at a heating rate of ≤80°C / h, held for 2 hours, then heated to 860°C at a heating rate of ≤120°C / h, held for 2.0 min / mm, and then cooled to 200°C after exiting the furnace. The quenching is then stopped and the forgings are returned to the furnace for tempering heat treatment. The ring forgings are heated to 600°C at a heating rate of ≤50°C / h, held for 2.3 min / mm, and then cooled to 420°C at a cooling rate of 110°C / h. The ring forgings are heated to 520°C at a heating rate of ≤40°C / h and kept warm for 1.8 min / mm. They are then furnace cooled at a cooling rate of ≤40°C / h. When the temperature of the ring forgings is below 250°C, they are taken out of the furnace and air-cooled.
[0026] The residual stress and mechanical properties of the ring forgings in each embodiment are shown in the following table: The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.
Claims
1. A heat treatment method for medium carbon bearing steel ring forgings with low residual stress, characterized in that: The following steps are involved: Step 1: Perform quenching and tempering treatment on the ring forging; Step 2: Cool the ring forging after quenching and tempering; the specific method is as follows: When the chemical composition of the ring forging satisfies P+S+As+10×(Sn+Sb)>0.085 or Mn+Si+Cr+Ni>2.6, the cooling rate is set to 60℃ / h-120℃ / h and the cooling temperature is set to 400℃-450℃; Otherwise, the cooling rate of the ring forging is set to 40℃ / h-80℃ / h and the cooling temperature is set to 450℃-500℃; Step 3: Perform stress relief annealing on the cooled ring forging.
2. The heat treatment method for medium carbon bearing steel ring forgings with low residual stress according to claim 1 is characterized in that: The specific process of quenching and tempering ring forgings is as follows: S1.
1. Heat the ring forging to 650℃±20℃ at a heating rate of ≤80℃ / h and keep it at this temperature for 1h-3h; S1.
2. Heat to 860°C ± 10°C at a heating rate of ≤ 120°C / h and hold for 1.8 min / mm-2.2 min / mm; S1.3, quench and cool the ring forging; S1.
4. Return to the furnace for tempering heat treatment.
3. The heat treatment method for medium carbon bearing steel ring forgings with low residual stress according to claim 2, characterized in that: The method for quenching and cooling the ring forging is: Liquid-cool the ring forgings after heating and insulation in S1.2, and ensure that the temperature of the ring forgings after leaving the water is returned to 200℃±20℃.
4. The heat treatment method for medium carbon bearing steel ring forgings with low residual stress according to claim 3, characterized in that: The method for tempering heat treatment of ring forgings after quenching and cooling is: Heat the ring forging to 620℃±30℃ at a rate of ≤50℃ / h and keep it warm for 2.2min / mm-2.5min / mm.
5. The heat treatment method for medium carbon bearing steel ring forgings with low residual stress according to any one of claims 1 to 4, characterized in that: The method for stress relief annealing of the cooled ring forging is as follows: The ring forging is heated to 530℃±30℃ at a heating rate of ≤40℃ / h and kept warm for 1.8min / mm-2.2min / mm; The furnace is cooled at a cooling rate of ≤40°C / h. When the temperature of the ring forging is below 300°C±50°C, the ring forging is taken out of the furnace and air-cooled.
6. The heat treatment method for medium carbon bearing steel ring forgings with low residual stress according to any one of claims 1 to 4, characterized in that: The method for stress relief annealing of the cooled ring forging is as follows: When the chemical composition of the ring forging meets P+S+As+10×(Sn+Sb)>0.085 or Mn+Si+Cr+Ni>2.6, the holding temperature is set to 500℃-530℃, otherwise the holding temperature is 530℃-560℃; When the effective thickness of the ring forging is ≤100mm or the shape is asymmetric, the furnace cooling temperature is set to 250℃-300℃, otherwise the furnace cooling temperature is 300℃-350℃.