Method for restraining internal oxidation in gear deep carburizing and quenching process

Abstract

The invention discloses a method for restraining internal oxidation in the gear deep carburizing and quenching process. The method includes the first carburizing stage, the second carburizing stage, the high-temperature tempering step, the quenching step and the low-temperature tempering step. At the first carburizing stage, carburizing is conducted on a gear in a 920-DEG C carburizing furnace under the assigned carbon potential condition. At the second carburizing stage, the temperature in the carburizing furnace is kept, carburizing is conducted for a preset period of time under the assigned carburizing condition, homeothermy is conducted at the temperature of 860 DEG C for 2-3 hours, and the gear is taken out of the furnace and cooled. In the high-temperature tempering step, the temperature is kept for 4 hours after the gear is heated to 640 DEG C in a tempering furnace. In the quenching step, heat preservation is conducted on the gear for 6 hours at the temperature of 830-840 DEG C, and the gear is placed in saline water at the assigned temperature to be quenched after being taken out of the furnace. In the low-temperature tempering step, the gear is placed in the tempering furnace to be heated to 210-230 DEG C, the temperature is kept for 9-10 hours, and then the gear is taken out of the furnace and cooled in air. The method is easy to operate, internal oxidation of 8 micrometers can be reduced on the basis of an existing control index through a four-segment method and carbon potential control; and meanwhile, the problems that metallographic structures of the gear deteriorate, carbide and retained austenite exceed the standard requirements and finally the service life of the gear is shortened are avoided.

Description

technical field [0001] The invention relates to a method for suppressing oxidation in a carburizing and quenching process, in particular to a method for suppressing oxidation in a deep carburizing and quenching process of gears, and belongs to the technical field of heat treatment. Background technique [0002] In recent years, as the speed of trains has raised new challenges to the performance of locomotives, higher requirements have been placed on the performance of locomotive gears, requiring gears to have sufficient strength and impact toughness to ensure , Absolutely safe and reliable; the gear surface is required to have excellent hardness and wear resistance, so as to ensure good contact fatigue performance and improve gear life. Gears are crucial components directly related to train safety for high-speed trains. Therefore, all countries in the world attach great importance to the research and development of materials and processes for locomotive gears. [0003] At p...

AI Technical Summary

Problems solved by technology

[0004] However, the control and reduction of internal oxidation in the current technical solution cannot meet the ME level requirements of gears in ISO6336-5 "Calculation of Bearing Capacity of Straight and Helical Gears Part 5 Strength and Quality of Materials". Able to meet MQ level requirements

[0005] In the standard of ISO6336-5 "Calculation of Bearing Capacity of Straight and Helical Gears Part 5 Strength and Quality of Materials", the index of internal oxidation increases with the increase of carburized layer depth. The existing process method There is no corresponding process method for the reduction of internal oxidation in deep carburizing

Images