MAKING METHOD OF LOW TEMPERATURE NI-STEEL

摘要

The method improves mechanical properties at the temperature range of -80 deg.C to -110 deg.C by adding Mo and Nb elements and controlling the conditions of hot working and cooling. The method comprises; (A) heating a slab with 0.02-0.1% C, 2.5-4.0% Ni, 0.05-0.2% Mo, and 0.02-0.04% Nb at 1200 deg.C -1300 deg.C; (B) hot rolling the heated slab with 40% total reduction; (C) cooling to room temperature with average cooling rate of 10 deg.C per second; and (D) tempering at 600 deg.C - 650 deg.C.