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Thermal treatment method for large-section axle-type forge pieces

A heat treatment method and large cross-section technology, applied in the field of heat treatment, can solve the problems of steam film generation, failure to meet the process requirements of rapid cooling and uniform cooling, and the inability to adjust the cooling speed in the air cooling chamber, so as to achieve the effect of high strength and toughness

Inactive Publication Date: 2016-08-24
天津鼎元热工工程有限公司
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Problems solved by technology

[0003] Among them, the air cooling process of the normalizing process mainly adopts the layout of the wind direction with large flow and low wind pressure and the wind direction flows along the axial direction of the workpiece. The disadvantage of this layout is that it cannot meet the process requirements of rapid cooling and uniform cooling.
At the same time, the known air-cooled chamber cannot adjust the cooling speed, because the specific heat capacity of the air will change greatly with the change of temperature and humidity, so it cannot meet the axles of high-speed trains, subways and heavy-duty trucks that are more refined and higher standards technical requirements
[0004] In the past, the quenching of large-section shaft forgings usually uses ordinary water as the medium, which is easy to cause vapor film due to the vaporization of water by the high-temperature workpiece, and finally fails to achieve the proper cooling rate, so it cannot be used on the forging 65- Dense martensite or lower bainite is formed in the core of 75mm
At the same time, due to the irregularity of the vapor film, the surface structure of the workpiece cannot be uniform
[0005] With the increase of the size of forgings and the improvement of performance requirements, the influence of the structure and mechanical properties of the core of the workpiece on the overall performance is increasing. The traditional heat treatment process has gradually been unable to meet the requirements for the structure and mechanical properties of the core of the workpiece. Moreover, the performance of the core of the product and the performance of the surface layer are often different.

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  • Thermal treatment method for large-section axle-type forge pieces

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Embodiment Construction

[0014] The heat treatment method for a large-section shaft forging provided by the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0015] The heat treatment method for a large-section shaft forging provided by the present invention includes the following steps in order:

[0016] 1) Normalize the large cross-section shaft forgings at a heating rate of 4-7°C / min, then hold at a temperature of 910-930°C for 220-260 minutes, and then wind them at a cooling rate of 60-70°C / min. Cool to 500-600°C, and then air-cool to below 150°C at a cooling rate of 5-10°C / min; in this step, known heating equipment can be used to normalize and heat-preserve the forgings, and then use the graded controllable jet flow method Air-cooling is used for cooling. For example, a high-pressure fan can be used to drive cold air into the angle-shaped static pressure box, and the cold air can be evenly sprayed on the surface of the fo...

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Abstract

The invention discloses a thermal treatment method for large-section axle-type forge pieces. The thermal treatment method comprises the following steps that a forge piece is normalized with a temperature increasing rate of 4-7 DEG C / min; heat preservation is performed at 910-930 DEG C; the forge piece is air cooled to 500-600 DEG C with a temperature decreasing rate of 60-70 DEG C / min; the forge piece is air cooled to be below 150 DEG C with a temperature decreasing rate of 5-10 DEG C / min; quenching is performed with a temperature increasing rate of 4-7 DEG C / min; heat preservation is performed at 860-880 DEG C; then quenching is performed; the forge piece is rapidly cooled to be below 150 DEG C with a temperature decreasing rate of 100-150 DEG C / min; the forge piece is placed into an oil cooling system for cooling; tempering is performed with a temperature increasing rate of 4-7 DEG C / min; heat preservation is performed at 640-660 DEG C; and the forge piece is air cooled to an operable temperature with a temperature decreasing rate of 5-10 DEG C / min. By adopting the thermal treatment method, the large-section axle-type forge piece can get a good metallographic structure, and have high strength and toughness; and particularly, the core part structure of the large-section axle-type forge piece can be refined, so that the core part and the superficial structure of the large-section axle-type forge piece have the same metallographic structure and mechanical property.

Description

technical field [0001] The invention belongs to the technical field of heat treatment, in particular to a heat treatment method for a shaft forging with a large section. Background technique [0002] At present, the post-forging heat treatment of large cross-section shaft forgings such as rail vehicle axles in China basically adopts two times of normalizing and tempering or quenching and tempering. [0003] Among them, the air cooling process of the normalizing process mainly adopts the layout of the wind direction with large flow and low wind pressure and the wind direction flows along the axial direction of the workpiece. The disadvantage of this layout is that it cannot meet the process requirements of rapid cooling and uniform cooling. At the same time, the known air-cooled chamber cannot adjust the cooling speed, because the specific heat capacity of the air will change greatly with the change of temperature and humidity, so it cannot meet the axles of high-speed trains...

Claims

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Application Information

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IPC IPC(8): C21D9/28C21D1/28C21D1/18C21D1/60
CPCC21D9/28C21D1/18C21D1/28C21D1/60
Inventor 隋轶
Owner 天津鼎元热工工程有限公司
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