PURPOSE: To manufacture a steel pipe for oil well excellent in sulfide stress corrosive cracking resistance even in a sulfide stress corrosive environment.
CONSTITUTION: This steel pipe for oil well is manufactured by executing hot piercing continuous rolling to a steel billet incorporating boron and titanium or further selectively incorporating a little quantity of chromium, molybdenum, nickel and vanadium at 900-700°C temp. in a final stage and 3-15% rolling reduction ratio and reheating a hollow raw pipe lowered to Ar3-100°C-Ar3+50°C at 900-1000°C and rapidly cooling a finished steel pipe, which is obtd. by executing hot finish rolling at ≥Ar3+50°C finish temp., from ≥Ar3 point and successively, executing tempering treatment at ≤Ac1 point. By this method, the steel pipe for oil well having high strength and excellent sulfide stress corrosive cracking resistance is obtd.
ASAHI HITOSHI
UENO MASAKATSU
