| 摘要 |
PROBLEM TO BE SOLVED: To provide a producing method of a martensitic welded stainless steel pipe, by which a product excellent in quality at the welded part can stably by produced. SOLUTION: After forming the martensitic stainless steel sheet containing, by weight of <=0.03% C and 7-14% Cr into an open-pipe state with the ordinary method, plasma welding is executed to both mutually faced edge parts by using working gas composed of Ar gas or mixed gas of Ar and He containing <=5 vol.% hydrogen concn. as impurity. After flush-welding with a TIG welding to the welded part with the plasma welding, at least to the welded part, hardening at a temp. of 800-1,100 deg.C and tempering at a temp. of 500-700 deg.C, are applied.
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