Thermal treatment method for carburizing and quenching of gearbox gears

Abstract

The invention discloses a thermal treatment method for carburizing and quenching of gearbox gears. The thermal treatment method includes the steps of A, carburizing, B, quenching and C tempering. In the step of A, carburizing, the gears are placed in a heating furnace, the temperature of the heating furnace is increased from the room temperature to the temperature of 850-900 DEG C for carburizing, and carburizing time is 2-5 h; the carburizing process includes a beginning stage, a strong carburizing stage and a diffusion stage; the carbon potential (CP) of the beginning stage is 0.9-1 C%, the CP of the strong carburizing stage is 1-1.1 C%, and the CP of the diffusion stage is 0.8-0.9 C%; the time of the beginning stage is 12-15 min, the time of the strong carburizing stage is 200-220 min, and the time of the diffusion stage is 20-40 min. In the step of B, quenching, the carburized gears are cooled to 810-850 DEG C, then temperature equilibrium is carried out for 20-40 min, and then the gears are quenched in quenching oil with the temperature being 85-95 DEG C. In the step C, tempering, the quenched gears are subjected to tempering at the temperature of 155-170 DEG C for 1-2 h.

Description

technical field

[0001] The invention relates to a heat treatment method for carburizing and quenching of transmission gears. Background technique

[0002] The gear of the automobile transmission is one of the parts with the highest technical requirements. During the operation of the gear, there are both rolling and sliding between the meshing tooth surfaces, and the gear is also subjected to pulse stress and alternating bending stress. Therefore, it is required Gears need to be heat-treated to have good hardness, wear resistance, fatigue resistance, high dimensional accuracy, and low noise during operation.

[0003] Carburizing and quenching and carbonitriding are the most important heat treatment methods for surface strengthening of gearbox gears. In the existing carburizing and quenching, the carburizing temperature is usually 920-940°C, and the carburizing carburizing potential CP is usually 1.0-1.2C%, in order to obtain a high-quality carburizing surface layer, but it h...