C: 0.040%-0.080% Si: 0.75% max Mn: 2.00% max P: 0.035% max S: 0.015% max Cr: 16.0%-18.0% Mo: 2.00%-2.50% Ni: 12.0%-14.0% Ti: 5×C-0.80% B: 0.0015%-0.0060%