Steel grain refining heat treatment method for heavy-load locomotive gear

Abstract

The invention discloses a steel grain refining heat treatment method for a heavy-load locomotive gear. The method comprises the steps of S1, carburization, wherein steel for the gear is placed into a carburizing furnace, after the temperature rises to the first temperature, carburization is carried out, and after the temperature drops to 860 DEG C+ / -5 DEG C and is constant, the steel is cooled to the room temperature; S2, isothermal normalizing, wherein the steel is subjected to heat preservation for a hour at the temperature being 900 DEG C + / -5 DEG C, and after the steel is subjected to air cooling to be at the second temperature, heat preservation is carried out for b hour, and the steel is subjected to air cooling to be at the room temperature; S3, one-time quenching, wherein after the steel is heated to 840 DEG C+ / -5 DEG C and subjected to heat preservation, the steel is discharged out of the furnace, and oil quenching is carried out; S4, high-temperature tempering, wherein after the steel is heated to the third temperature and subjected to heat preservation for c hour, the steel is subjected to air cooling to be at the room temperature; S5, secondary quenching, wherein after the steel is heated to 820 DEG C+ / -5 DEG C and subjected to heat preservation, the steel is discharged out of the furnace, and oil quenching is carried out; and S6, low-temperature tempering, wherein after the steel is subjected to heat preservation for d hour at the fourth temperature, the steel is subjected to air cooling to be at the room temperature. The grain refining heat treatment method is adopted, the material structure is improved, the toughness, the impact toughness, the wear-resisting property, the fatigue strength and the anti-corrosion property of materials can be improved, and the comprehensive mechanical property of the product is good.

Description

technical field [0001] The invention relates to a heat treatment method, in particular to a heat treatment method for refining steel grains for heavy-duty locomotive gears, and belongs to the technical field of heat treatment. Background technique [0002] In recent years, with the speed increase of trains, new challenges have been put forward for the performance of locomotives, and higher requirements have been put forward for the performance of locomotive gears. Gears are required to have sufficient strength and impact toughness to ensure absolute safety and reliability under the highest speed and load; gear surfaces are 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. ...

AI Technical Summary

Problems solved by technology

[0004] This method can effectively improve the surface hardness and wear resistance of the gear, and improve the contact fatigue performance of the gear, but it has the following disadvantages: the gear carburizing temperature is high and the holding time is long, the grains are coarse after carburizing, and the martensitic surface layer after quenching The body needle is thicker, which reduces the strength and toughness of the gear, and reduces the comprehensive mechanical properties of the gear

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