Disclosed in the present invention is a clean heat treatment control method for achieving high
hardness and minimal deformation of a cold-work die, comprising: double-stage isothermal high-pressure
gas quenching: introducing a high-pressure
gas quenching gas into a
vacuum furnace and stopping introduction of the high-pressure
gas quenching gas once the surface temperature of a cold-work die has been cooled to a metastable
austenite zone; enabling the temperature of a core portion of the cold-work die to be reduced to 50ºC above the metastable
austenite zone by means of gas circulation, and then continuing to introduce the high-pressure gas
quenching gas until the surface temperature of the cold-work die is reduced to a
martensite point or below; then continuing to heat the cold-work die to a lower
bainite zone, maintaining the temperature to enable the core portion to undergo lower
bainite transformation, and then cooling the cold-work die to
room temperature; and then carrying out high-temperature
tempering two or three times. According to the present invention, two-stage vacuum high-pressure gas
quenching isothermal treatment, i.e., vacuum high-pressure gas
quenching and isothermal quenching in the metastable
austenite zone and the lower
bainite zone, is performed, and thermal stress and
structural stress are controlled by means of the two-stage isothermal treatment so as to control the deformation of the die, thereby achieving accurate control of the structure and stress, controlling the deformation of the die to be within 0.05%.