Patent ID: 7670547

Claim:
Low alloy steel for oil country tubular goods having high sulfide stress cracking resistance, comprising, in percentage by mass, 0.20% to 0.35% C, 0.05% to 0.5% Si, 0.05% to 0.6% Mn, at most 0.025% P, at most 0.01% S, 0.005% to 0.100% Al, 0.8% to 3.0% Mo, 0.05% to 0.25% V, 0.0001% to 0.005% B, at most 0.01% N, and at most 0.01% O, the balance comprising Fe and impurities, said low alloy steel satisfying Expression (1): 12V+1−Mo≧0 (1) where the symbols of elements represent the contents of the elements in percentage by mass.