PURPOSE: To give the whole pipe uniform and excellent strength and ductility and to improve the dimensional accuracy by induction-heating a high Cr ferritic welded steel pipe having the specific composition at the specific temp. while rotating and next cooling while rotating.
CONSTITUTION: The high Cr ferritic welded steel pipe having alloy composition composing by wt.% of 0.04W0.20% C, ≤1.0% Si, 0.1W1.5% Mn, 6W15% Cr, 0.01W3% Mo, 0.05W0.4% V, 0.01W0.30% Nb and if necessary ≤3% W and the balance Fe with inevitable impurities is produced. This welded steel pipe is heated at 1,000W1,080°C for ≥4min by using the induction heating coil while rotating. Next, it is cooled while rotating as the same way. As the heating and cooling are executed to the whole steel pipe after welding, the strength and the ductility of the welded part and welding heat effected part deteriorated by welding are sufficiently recovered.
NAKANISHI HISAYUKI
MATSUI TAKASHI
ISEDA ATSURO
| JPS6237321A | 1987-02-18 | |||
| JPS61149437A | 1986-07-08 | |||
| JPS5321022A | 1978-02-27 |