METHOD OF COMBINED CHEMICAL-THERMAL PROCESSING OF STRUCTURAL HOT-STRENGTH STEEL Russian patent published in 2017 - IPC C23C8/34 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, in particular, to a method of combined chemical-thermal processing of parts from a hot-strength steel intended for making high-loaded gears of reduction gears for aviation equipment serviceable at heating in the contact zone of up to 500 °C. Performed is preliminary thermal processing by normalizing at the temperature of (950±10) °C with air cooling, high tempering at the temperature of (650±10) °C with maintaining for 3 hours, cooling in the air, hardening in oil at the temperature of (960±10) °C, repeated high tempering at the temperature of (660±10) °C with maintaining for 3 hours and cooling in the air. That is followed be vacuum cementation at the temperature of 940°C and thermal hardening by quenching, intermediate temperings, cold processing and repeated tempering. After thermal hardening the saturated carbide zone is removed from the cemented layer surface by grinding to the depth of 0.2–0.25 mm, after which gas nitriding is performed at (480–500) °C.

EFFECT: provided is significantly increased contact service life (the main characteristic for heavily loaded gears), fatigue strength and wear resistance.

1 cl, 1 dwg, 1 tbl, 1 ex