HEAT TREATMENT OF MARTENSITE STAINLESS STEEL AFTER ELECTRIC SLAG REMELTING (ESR) Russian patent published in 2015 - IPC C21D3/06 C21D6/00 C21D1/78 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy. To increase fatigue strength of martensite stainless steel the ESR is performed, then the produced ingot is cooled, and at least one austenite thermal cycle is performed, it includes the ingot heating to temperature above the austenitising temperature followed by the cooling stage. During cooling, before the moment when the minimum temperature of the ingot is below temperature Ms, the ingot is held at temperature above temperature Ac3 till beginning of the next austenite cycle, or is held at holding temperature within range of "nose" of ferrite-pearlite transformation during holding time which is longer then period sufficient for maximum possible austenite transformation to the ferrite-pearlite structure in the ingot at holding temperature, at that the ingot is held at the holding temperature just after achievement of the holding temperature by the temperature of the most cold point of the ingot; then last austenite thermal cycle is performed, it includes the ingot heating above Ac3, then final cooling stage is executed, at that the ingot is held at temperature within range of "nose" of ferrite-pearlite transformation, as specified above; at that after final cooling the ingot is not subjected to treatment in austenite thermal cycle above mentioned.

EFFECT: increased fatigue strength of the martensite stainless steel.

8 cl, 6 dwg, 1 tbl