Heat processing method for carburizing and quenching

Abstract

The invention discloses a heat processing method for carburizing and quenching. The method comprises the following steps: A) a carburizing step, placing a gear in a heating furnace, and rising temperature of the heating furnace from room temperature to 850-900 DEG C for carburizing for 2-5 h, wherein the carbon potential CP in a strong carburizing stage is 1.02-1.1C%, and the carbon potential CP in a diffusion stage is 0.8-0.9C%; B) a quenching step: cooling the obtained carburized gear to 810-850 DEG C, equalizing the temperature for 20-40min, and quenching in 85-95 DEG C quenching oil; and C) a tempering step: tempering the obtained quenched gear at 155-170 DEG C for 1-2 h. The proper reduction of the carburizing temperature and the quenching temperature, the rising of the temperature of the quenching oil and the proper rising of the carburizing carbon potential are carried out on the premise of guaranteeing the quality of a carburized layer, so the carburizing time is not prolonged, and the energy consumption is reduced; and the appearance of black microstructures is prevented, so the surface hardness, the wear resistance and the fatigue strength of the gear are obviously improved, deformation is reduced, the driving balance of the gear is improved, noises are reduced, and the service life of the gear is prolonged.

Description

technical field [0001] The invention relates to a heat treatment method of carburizing and quenching. 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 has the following shortc...

AI Technical Summary

Problems solved by technology

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 has the following shortcomings: 1. The carbon temperature is high, the time is long, and the energy consumption is large; 2. Large deformation; 3. There is black structure, resulting in low hardness, reducing fatigue resistance, reducing wear resistance, and shortening service life