The invention provides a
thermal treatment method for reducing secondary gear ring nitrogenized deformation. The method comprises the following steps: (a)
tempering after a secondary gear ring is roughly processed; (b)
tempering; (c)
processing by a gear milling
machine, and destressing at high temperature; (d)
processing by a
gear grinding machine, and performing gas nitrogenization, wherein the gas nitrogenization comprises the following steps: uniformly fixing and supporting a plurality of cylindrical clamps in a gear ring groove; flushing a gear ring in a bell type gas nitrogenation oven, heating, and introducing 8-12m<3> / h
nitrogen for 3-5 hours; heating to 400-500 DEG C, introducing 4-8m<3> / h
ammonia, and insulating for 0.2-0.8 hours; heating to 500-550 DEG C, controlling the flow rate of
ammonia to be 10-15m<3>, and penetrating for 60-65 hours, wherein Kn is 6; turning to diffuse, controlling the flow rate of
ammonia at 4-6m<3> / h, and diffusing for 30-32 hours, wherein Kn is 2; cooling along with the oven, introducing 8-12m<3> / h
nitrogen while cooling; moving the heating mantle when the temperature is reduced to 400-500 DEG C; discharging parts from the oven when the temperature is reduced to lower than 90 DEG C. The
thermal treatment method has the characteristics that the deformation is small, a high-
hardness high-wearing
nitride layer can be obtained on the surface, the
contact fatigue strength can be improved, the drawing performance and accurate requirement can be fulfilled, the product quality can be improved, and the like.