| 摘要 |
Provided is a low-alloy steel pipe for an oil well, which has a yield strength of 827MPa or more, and excellent SCC resistance. This low-alloy steel pipe for an oil well includes, in mass%, C: over 0.35 and up to 0.65%, Si: 0.05-0.50%, Mn: 0.10-1.00%, Cr: 0.40-1.50%, Mo: 0.50-2.00%, V: 0.05-0.25%, Nb: 0.01-0.04%, sol. Al: 0.005-0.10%, N: 0.007% or less, Ti: 0-0.012%, and Ca: 0-0.005%. The remainder comprises Fe and impurities, the impurities comprising 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. In this structure, the number of cementites that have a circle equivalent diameter of 200nm or more is 200/100μm2 or more, and the yield strength is 827MPa or more. |
