THERMAL TREATMENT METHOD TO PRODUCE PARTS WITH HIGH DIMENSIONAL ACCURACY Russian patent published in 2020 - IPC C21D1/78 

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy, particularly, to heat treatment of fasteners of nuclear reactors. In the method of heat treatment of fasteners of nuclear reactors from steels of bainite class, including heating for quenching of workpieces from temperatures by 30–50 °C above point Ac₃ with holding for 1.5–2 min/mm of cross-section and subsequent high tempering at temperature of 630–700 °C with holding for 5–6 min/mm of cross-section with air cooling, machining of finished parts with allowance for chemical-thermal treatment, chemical-thermal treatment and subsequent thermal improvement, according to invention after chemical heat treatment of part is repeatedly subjected to quenching and high tempering by identical mode of preliminary heat treatment and performing additional tempering in temperature range 450±10 °C with holding for 2.0–7.0 hours with further cooling in air.

EFFECT: method enables to obtain fasteners of nuclear reactors of steels of bainitic type with high dimensional accuracy at maintaining given mechanical properties.

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