Patent ID: 10563793

Abstract:
Provided is a low alloy oil-well steel pipe having a yield strength of 827 MPa or more, and an excellent SSC resistance. The low alloy oil-well steel pipe according to the present invention consisting of: in mass %, C: more than 0.35 to 0.65%; Si: 0.05 to 0.50%; Mn: 0.10 to 1.00%; Cr: 0.40 to 1.50%; Mo: 0.50 to 2.00%; V: 0.05 to 0.25%; Nb: 0.01 to 0.040%; sol.Al: 0.005 to 0.10%; N: 0.007% or less; Ti: 0 to 0.012%; Ca: 0 to 0.005%; and a balance being Fe and impurities, the impurities including: P: 0.020% or less; S: 0.002% or less; O: 0.006% or less; Ni: 0.10% or less; Cu: 0.03% or less; and B: 0.0005% or less, wherein in a microstructure, a number of cementite particles each of which has an equivalent circle diameter of 200 nm or more is 200 particles/100 μm2 or more, and a yield strength is 827 MPa or more.