STAINLESS SEAMLESS STEEL PIPE EXCELLENT IN CORROSION RESISTANCE AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain a black film-coated seamless steel pipe of a 13Cr series stainless steel excellent in corrosion resistance by providing at least the surface in a stainless seamless steel pipe contg. a specified amt. of Cr with a scale layer as an internal layer and incorporating the scale layer with FeCr₂O₄ and a specified ratio or above of Fe₂SiO₄. ;SOLUTION: This stainless steel pipe is the one in which at least the surface in the pipe is provided with a scale layer as an internal layer 4 and contg. 11 to 15 wt.% Cr, and the scale layer is incorporated with FeCr₂O₄ and ≥5 vol.% Fe₂SiO₄ or incorporated with FeCr₂O₄, FeO and Fe₂SiO₄. In the case of the former, the adhesion of scale is improved, and in the case of the latter, its corrosion resistance and adhesion are remarkably improved. The latter steel pipe can be obtd. by subjecting a pipe to heating treatment in an atmospheric gas contg. 15 to 25 vol.% water vapor in a stage after piercing by a Mannesman-mandrel mill pipe making method.;COPYRIGHT: (C)1999,JPO