METHOD OF STEEL HEAT TREATMENT Russian patent published in 2013 - IPC C21D1/78 C21D1/28 C21D1/56 C22C38/04 

FIELD: metallurgy.

SUBSTANCE: heat cycling is performed with heating and tempering. Note here that low-alloy steel containing in wt % 0.5-0.25 of C and 1.2-1.5 of Mn are subjected to this heat treatment. Heat cycling is performed with heating to austenitising temperature of 930°C and subjected to accelerated cooling at the rate of 0.2-0.8 deg/s. Note here that articles are heated in first cycle jointly with furnace and cooled with acceleration. Note that in intermediate cycles, heating is accelerated to 50-70 deg/s in furnace heated to 930°C and held therein for 10 min to rule out a full homogenisation of austenite and subjected to accelerated cooling to 400°C. Note also that in final cycle, its if cooled to room temperature. Mind that the number of cycles makes 5 while tempering is performed at 400°C for 2 h.

EFFECT: higher mechanical properties.

2 tbl, 3 dwg