To provide a ferritic stainless steel welded pipe excellent in expanding workability free from a crack in pipe expansion working occurring at a welding part or near the welding part in the pipe expansion working of two times or more of a pipe stock.
In the ferritic stainless steel welded pipe of the ferrite-single phase containing 0.1-0.5 mass% of one kind or two kinds of Ti and Nb respectively, a hardness difference ΔHV(=HVW-HVM) between Vickers hardness HVW of the welded part and Vickers hardness HVM of the base material part lies in the range of 10-40, and a ratio RT(=TW/TM) between the bead thickness TW of the welded part and the wall thickness TM of the base material part lies in the range of 1.05-1.3. Further, after forming and welding, correction of 0.5-2.0% in the circumferential length is carried out. Furthermore, the welded pipe is annealed at 700-850°C after forming, welding and correcting work.
TAGAMI TOSHIO
SATSUNOKI TOMIO
KOMORI TADASHI
YAMAMOTO SHUJI
| JP2005271040A | 2005-10-06 |
Hisataka Tanaka
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