CPC G04B 37/22 (2013.01) [C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/48 (2013.01); G04B 37/0008 (2013.01); C21D 2211/001 (2013.01); C21D 2211/005 (2013.01)] | 12 Claims |
1. An austenitic ferritic stainless steel comprising:
a base portion composed of a ferrite phase;
a surface layer composed of an austenitic phase; and
a mixed layer formed between the base portion and the surface layer, and in which the ferrite phase and the austenitic phase are mixed wherein
the base portion contains Cr: 18 to 22 mass %, Mo: 1.3 to 2.8 mass %, Nb: 0.30 to 0.50 mass %, Cu: 0.1 to 0.2 mass %, Ni: less than 0.5 mass %, Mn: 0.5 to 0.8 mass %, Si: less than 0.5 mass %, P: less than 0.10 mass %, S: less than 0.05 mass %, N: less than 0.05 mass %, C: less than 0.05 mass %, and a balance being composed of Fe and inevitable impurities, wherein
the surface layer contains 1.0 to 1.6 mass % of nitrogen, wherein
the surface layer includes, at a surface of the surface layer, an oxide film having a thickness of 2.5 nm or greater, as calculated using oxygen profiles obtained by AES analysis.
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