The invention relates to a heat treatment method of a bearing. The heat treatment method comprises the following six steps of: heating, insulating,
quenching, cleaning,
cold treatment and
tempering. The heat treatment method is characterized in that before the heating step, a fining treatment step of
carbide is arranged; the fining treatment step comprises two steps of
forging and spheroids annealing; the temperature of initial
forging in the
forging steps is 1050-1150 DEG C; the insulating time is 70-90 minutes; the temperature of the final forging and forming is 800-900 DEG C; then the stirring and cooling are carried out in boiling water till the temperature is 300-600 DEG C; the bearing is taken out of water and air-cooled till
room temperature; and the spheroids annealing step comprises specific steps of: heating to 790-810 DEG C, insulating for 150-210 minutes under the temperature,
air cooling to 680-710 DEG C, insulating for 4-6 hours, cooling till 650 DEG C along with a furnace, taking out of the furnace and carrying out
air cooling. The cold-treatment step is carried out in 2 hours after the cleaning steps is finished after
quenching,
liquid nitrogen is adopted as
cooling medium, cooling is carried out till the temperature is minus 70-minus 80 DEG C, insulation is carried out for 1.5-2 hours under the temperature, and returning the temperature naturally till the
room temperature. The heat treatment method has the
advantage that the service life of the bearing is prolonged by fining
carbide particles, improving the
hardness and controlling the content of the retained
austenite in the metallographic structure.