| 摘要 |
PURPOSE:To manufacture the titled Cr-Mo steel excelling in creep strength as well as in weldability by subjecting the Cr-Mo steel which has a specific composition and whose content of Nb, C, and V is controlled by means of a specific equation to normalizing, tempering, and stress relieving under specific conditions. CONSTITUTION:The Cr-Mo steel consisting of 0.04-0.12% C, 0.01-0.60% Si, 0.20-1.20% Mn, 1.80-3.50% Cr, 0.80-2.20% Mo, 0.01-0.30% Nb, 0.01-0.50% V, <=0.015% Ti, 0.0002-0.0020% B, <=0.015% P, <=0.010% S, 0.005-0.040% SolAl, <=0.0040% N, and the balance Fe with inevitable impurities and having the relation represented in equation I among Nb, C, and V is normalized or hardened in the higher temp. range between those represented by expressions II and III. Succeedingly the steel is subjected to tempering and stress relieving in the temp. range from 650 deg.C to Ac1 point. |
