| 摘要 |
PURPOSE:To improve both toughness and creep strength simultaneously by subjecting the Cr-Mo steel having a specific composition to rolling, normalizing or hardening under specific temp. conditions, and tempering. CONSTITUTION:The steel consisting of, by weight, 0.01-0.60% Si, 0.20-1.20% Mn, 1.80-3.50% Cr, 0.802.00% Mo, 0.005-0.05% SolAl, <=0.015% P, <=0.010% S, 0.25-0.35% V, 5.67-0.15% (C/V), Ti in an amount of <=0.010% and satisfying inequality II, B in an amount of 0.0003-0.0010% and satisfying inequality III (N' means N unfixed by Ti), and the balance Fe with inevitable impurities is rolled, which is normalized or hardened in the temp. range from the temp. represented by expression I to 1,020 deg.C, followed by tempering. In this way, the Cr-Mo steel having simultaneously improved creep strength and toughness in spite of its thickness can be obtained without causing deterioration in weldability. |
