INFLUENCE OF HEAT-TREATMENT CONDITIONS ON THE PROPERTIES OF CAST VNL-3 STEEL

See adjacent abstract It was determined that optimum mechanical properties were obtained in precision cast steel VNL-3 ( < =0.08 carbon, 13-14.5 chromium, 4.4-5.5% nickel, 1.5-2.0 molybdenum, 1.2-1.75 copper by double heat treatment: heat to 1100 deg C, 1 h, air cool, temper at 600 deg C, 0.5 h; + quench from 970 deg C, cold work at --50 to --70 deg C, temper at 450 deg C. Higher ductility was obtained by the heat treatment: quench from 970 deg C, temper at 450 deg C, cold work at --50 to --70 deg C. Casting defects (carburization) were eliminated by raising the secondary heat treatment temperature to 1100 deg C. Properties obtained were sigma sub u = > 1100 N/mm exp 2 , delta = > 18%, a sub 1 = 90-110 J /cm exp 2 .