| 摘要 |
PROBLEM TO BE SOLVED: To provide a stainless steel pipe used as a cracking furnace pipe for an ethylene plant, and to provide a method for improving the carburization resistance and calking resistance of the pipe when used for it. SOLUTION: The stainless steel pipe comprises a main body made of a base metal containing, by mass%, 20-35% Cr, and a surface layer part having a Cr-deficient layer. The Cr-deficient layer contains 10% or higher Cr, and has a thickness of 20μm or thinner. The stainless steel may further have an oxidized scale layer mainly containing 50% or more Cr on the outer side of the Cr-deficient layer. The thickness of an oxidized scale layer is 0.1 to 15μm. Furthermore, the stainless steel may have the second oxidized scale layer mainly containing 50% or more Si, in between the above oxidized scale layer and the Cr-deficient layer. COPYRIGHT: (C)2005,JPO&NCIPI
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