| 摘要 |
PURPOSE:To improve the sulfide cracking resistance and yield strength of a steel contg. prescribed percentages of C, Si, Mn, P, S, Cr, Mo, Al and Ca by heat treating the steel under prescribed conditions. CONSTITUTION:A steel contg., by weight, 0.15-0.45% C, 0.05-0.8% Si, 0.3-1.7% Mn, <0.008% P, <=0.003% S, 0.2-1.5% Cr, 0.05-0.8% Mo, 0.01-0.1% Al and Ca satisfying Ca/S=1-10 is refined. The steel is rapidly heated to (the Ac3 point+30 deg.C) or above in a short time and quenched. The heat treatment is repeated once or more to make the austenite grains fine up to ASTM grain size No.10 or above. The steel is then tempered at the Ac1 point or below. |
