| 摘要 |
A high strength oil well seamless steel pipe excellent in sulfide stress cracking, which has a chemical composition that C: 0.1 to 0.20 %, Si: 0.05 t o 1.0 %, Mn: 0.05 to 1.0 %, Cr: 0.05 to 1.5 %, Mo: 0.05 to 1.0 %, Al: 0.10 % o r less, Ti: 0.002 to 0.05 %, B: 0.0003 to 0.005 %, with the proviso that the value of C(%) + (Mn(%)/6) + (Cr(%)/5) + (Mo(%)/3) is 0.43 or more, and the balance: Fe and inevitable impurities, with the proviso that in the impurities, P: 0.025% or less, S: 0.010 % or less, and N: 0.007 % or less. T he above oil well seamless steel pipe may contain one or more of specific amoun ts of V and Nb and/or one or more of specific amounts of Ca, Mg and REM. The production of the oil well steel pipe does not need a further heat treatment step for grain refinement, and therefore the above oil well steel pipe can b e produced by the employment of the inline pipe making-heat treatment process exhibiting high production efficiency, at a reduced cost. |
