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1. (WO2018003823) AUSTENITIC STAINLESS STEEL

Pub. No.:    WO/2018/003823    International Application No.:    PCT/JP2017/023657
Publication Date: Fri Jan 05 00:59:59 CET 2018 International Filing Date: Thu Jun 29 01:59:59 CEST 2017
IPC: C22C 38/00
C21D 6/00
C21D 8/00
C21D 8/10
C22C 38/58
Applicants: NIPPON STEEL & SUMITOMO METAL CORPORATION
新日鐵住金株式会社
Inventors: KOCHI, Norifumi
河内 礼文
NISHIYAMA, Yoshitaka
西山 佳孝
Title: AUSTENITIC STAINLESS STEEL
Abstract:
Provided is an austenitic stainless steel which has excellent carburization resistance even in a high-temperature carburization environment, and which also has excellent hot workability during the production. An austenitic stainless steel according to one embodiment of the present invention has a chemical composition that contains, in mass%, 0.03% or more but less than 0.25% of C, from 0.01% to 2.0% of Si, 2.0% or less of Mn, 10% or more but less than 22% of Cr, more than 30.0% but 40.0% or less of Ni, more than 2.5% but less than 4.5% of Al, from 0.01% to 3.5% of Nb, from 0.0005% to 0.05% of Ca, from 0.0005% to 0.05% of Mg and 0.03% or less of N, with the balance made up of Fe and impurities. The Cr concentration CCr' of the surface layer of this austenitic stainless steel and the Al concentration CAl' of the surface layer of this austenitic stainless steel satisfy formula (1) with respect to the Cr concentration CCr of portions other than the surface layer and the Al concentration CAl of portions other than the surface layer. 0.40 ≤ (CCr'/CAl')/(CCr/CAl) ≤ 0.80 (1)