METHOD OF HEAT TREATMENT OF DIE BLOCKS AND DIE MOULDS Russian patent published in 2014 - IPC C21D9/22 C21D1/607 

FIELD: machine building.

SUBSTANCE: invention can be used for heat treatment of die blocks from semi-heat-resistant and heat-resistant high viscosity steels for example "5ХНМ" and "4Х5МФС", and also die moulds from the steel "4Х5МФС". The method of heat treatment of die blocks and die moulds comprises the heating up to the temperature of quenching, curing at this temperature and cooling with consequent tempering. Cooling of die blocks and die moulds is performed in smelt of nitre at the temperature M_s - (20-30)°C, at the initial period of cooling ensure their intensive reciprocative move in a vertical direction within about three minutes, then it is cooled in rest within the total soak period in nitre smelt 10-15 minutes, then it is finally cooled in air, where M_s - temperature of start of martensitic transformation of steel - material of the tool. No water is permitted in structure of the molten nitre.

EFFECT: improvement of stability of die blocks and die moulds at the expense of the accelerated cooling at quenching in pearlitic temperature interval, moderate cooling in bainite temperature interval and very slow cooling in martensitic temperature interval, possibility to perform the quenching of die blocks and die moulds of any complication with minimum strain and minimum internal stresses, exception of cases of a cracking.

2 cl, 1 tbl, 1 ex