METHOD FOR HEAT TREATMENT OF BEARING PARTS MADE OF HEAT-RESISTANT BEARING STEEL (VARIANT) AND THE BEARING PART OBTAINED BY THE SPECIFIED METHOD Russian patent published in 2022 - IPC C21D9/40 C21D1/25 C21D6/04 

FIELD: metal processing.

SUBSTANCE: invention relates to the field of hardening heat treatment of bearing steel. A group of inventions has been claimed, including a method for heat treatment of bearing parts made of heat-resistant bearing steel in two versions and bearing parts obtained by this method. In the first variant of the claimed invention, a method for heat treatment of bearing parts made of heat-resistant bearing steel containing molybdenum, chromium, tungsten and vanadium as carbide-forming elements includes step heating for quenching, cooling and multiple tempering. At the same time, heating for quenching is carried out in vacuum, and the first heating is carried out to a temperature no higher than the temperature of noticeable coagulation of molybdenum carbides in the temperature range of 590-610°C with an exposure until the parts are completely heated. The specified first stage of heating does not require a high heating rate, the second heating is carried out at a high heating rate of at least 25°C per minute to a temperature slightly above the critical point A_c1 in the temperature range of 825-835°C with an exposure time of no more than 10-20 minutes. Final heating is also carried out at a rate of at least 25°C per minute to quenching temperatures in the range of 1060-1075°C, and subsequent cooling from quenching temperatures is carried out with nitrogen first at a pressure of at least 8 bar to 500-550°C, and then at a pressure of no more than 2 bar to a temperature of at least 50°C. After quenching, or after one or more stages of multiple tempering, cold treatment is carried out at a temperature of minus 70°C with an exposure of at least an hour and warming up to room temperature.

EFFECT: formation of a homogeneous fine-grained structure, reducing the amount of residual austenite to less than 3% and thereby ensuring the repeatability of the properties of products formed by heat treatment, reducing quenching stresses and, accordingly, increasing the reliability of bearing parts during operation.

14 cl, 1 tbl, 1 ex, 3 dwg