HIGH STRENGTH LOW CARBON CR-MO STEEL SHEET EXCELLENT IN LOW TEMPERATURE CRACKING RESISTANCE AND SR CRACKING RESISTANCE

摘要

PURPOSE: To obtain a low carbon Cr-Mo steel sheet having high strength and capable of preventing low temp. cracking and SR cracking. ;CONSTITUTION: This is a steel sheet contg. 0.03 to 0.12% C, 0.15 to 1.00% Si, 0.20 to 1.00% Mn, ≤0.020% P, ≤0.009% S, ≤0.04% Cu, 0.40% Ni, 0.40 to 3.50% Cr, 0.20 to 1.25% Mo, 0.005 to 0.09% V, 0.003% Sol.Al, ≤0.0035% O, 0.010 to 0.30% Ti and 0.0003 to 0.0020% B and the balance Fe with inevitable impurities and in which Ti and B satisfy the following inequality I and Cu, Ni and V satisfy the following inequality 2; or, it is a low carbon Cr-Mo steel sheet furthermore contg. 0.01 to 0.10% Nb or 0.0005 to 0.0100% Ca. The inequality I satisfies 0.23Ti+B-0.79N≤0.0003(%); where N denotes N(%) in the steel. The inequality 2 satisfies [{Cu+(Ni/2)+V}/Cr@9147/28}≤0.30.;COPYRIGHT: (C)1993,JPO&Japio