Heating for forging must be done slowly and uniformly. Soak through at 1900-2000°F, and reheat as often as necessary, stopping work when the temperature drops below 1650°F. After forging cool slowly in lime, mica, dry ashes or furnace. H10 hot work tool steel should always be annealed after forging.
Heat slowly to 1550-1650°F, hold until the entire mass is heated through, and cool slowly in the furnace (40°F per hour) to about 1000°F, after which the cooling rate may be increased. Suitable precautions must be taken to prevent excessive carburization or decarburization.
stress reliving when desirable to relieve the strains of machining, heat slowly to 1050-1250°F, allow to equalize, and then cool in still air.
Warm slightly before charging into the preheat furnace, which should be operating at about 1400-1500°F. 1.2365 hot work tool steel is a very deep hardening steel, and although oil quenching may be used where maximum hardness is required, air hardening is recommended for most applications. The use of salt bath or controlled atmosphere furnace is desirable to minimize decarburization, and if not available, pack hardening spent pitch temperature employed Annealing is usually in the range of 1800-1900°F.
Tempering practice may vary with size and application, but is usually performed in the temperature range of maximum secondary hardness or higher double tempering is recommended.