THERMOMECHANICAL PROCESSING OF LIGHTLY-ALLOYED STEELS Russian patent published in 2015 - IPC C21D8/00 C21D1/78 

FIELD: process engineering.

SUBSTANCE: invention relates to thermomechanical processing and can be used for production of critical elements of structures and various fasteners. To up the set of mechanical properties with elimination of steel inclination to reverse temper brittleness and to reach high mechanical and operating properties, workpiece of "35ХГСФ"-grade steel is subjected to cold plastic strain at reduction of 10-30%. Then, this workpiece is heated to subcritical temperatures Ac₁ - (5÷5)°C at the rate of 5÷20 deg/min and holding at said temperatures for 1.5÷3 hours. Then, at said subcritical temperature said workpiece is heated for quenching to Ac₃+(30÷40)°C and quenched in oil and tempered at 500÷550°C.

EFFECT: increased mechanical properties with elimination of steel inclination to reverse temper brittleness and high mechanical and operating properties.

1 tbl