US 11,669,049 B2
Watch component and watch
Koki Takasawa, Suwa (JP)
Assigned to SEIKO EPSON CORPORATION
Filed by Seiko Epson Corporation, Tokyo (JP)
Filed on Oct. 29, 2020, as Appl. No. 17/83,388.
Claims priority of application No. JP2019-197477 (JP), filed on Oct. 30, 2019.
Prior Publication US 2021/0132545 A1, May 6, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. G04B 37/22 (2006.01); C22C 38/48 (2006.01); C22C 38/44 (2006.01); C22C 38/42 (2006.01); C22C 38/00 (2006.01); G04B 37/00 (2006.01)
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
OG exemplary drawing
 
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.