PURPOSE: To produce a seamless low alloy steel tube having fine-grained structure and excellent in sulfide stress cracking resistance.
CONSTITUTION: A billet of a steel which has a composition containing 0.05-0.35% C, 0.01-0.5% Si, 0.15-2.5% Mn, 0.05-0.4% Mo, 0.005-0.1% Al, 0.005-0.1% Ti, and 0.005-0.1% Nb or further, if necessary, selectively containing small amounts of Cr, Ni, V, and B is formed into a hollow tube stock by means of continuous hot piercing rolling. The tube stock whose temp. is lowered to a temp. between 850°C and the Ar1 point is heated up to 900-1000°C and hot-finish-rolled at ≥(Ar3 point+50°C) finishing temp. and successively subjected to hardening treatment consisting of quenching from the above temp. and then to tempering treatment consisting of heating up to a temp. not higher than the Ac1 point and cooling, by which the seamless low alloy steel tube having fine-grained structure and excellent in sulfide stress cracking resistance can be produced.
ASAHI HITOSHI
UENO MASAKATSU
SATO HISAMI
TERASAWA TOMIO
| JPS58136715A | 1983-08-13 | |||
| JPS6075523A | 1985-04-27 |