	US 7,531,129 B2
	Stainless steel for high-pressure hydrogen gas
Masaaki Igarashi, Sanda (Japan); Hiroyuki Semba, Sanda (Japan); Mitsuo Miyahara, Kobe (Japan); Kazuhiro Ogawa, Nishinomiya (Japan); and Tomohiko Omura, Kishiwada (Japan)
Assigned to Sumitomo Metal Industries, Ltd., Osaka (Japan)
Filed on Apr. 18, 2005, as Appl. No. 11/108,099.
Application 11/108099 is a continuation of application No. PCT/JP2004/003797, filed on Mar. 19, 2004.
Claims priority of application No. 2003-079120 (JP), filed on Mar. 20, 2003.
Prior Publication US 2005/0178478 A1, Aug. 18, 2005
Int. Cl. C22C 38/46 (2006.01); C22C 38/58 (2006.01); C22C 30/00 (2006.01)

U.S. Cl. 420—48 [420/44; 420/46; 420/47; 420/586.1; 420/585; 420/584.1; 148/327; 148/419; 138/171; 138/142; 428/685]

20 Claims

1. A stainless steel having an austenitic microstructure for high-pressure hydrogen gas characterized in that:

(a) The steel consists of, by mass %, C: not more than 0.02%, Si: not more than 1.0%, Mn: 9.23 to 30%, Cr: more than 22% but not more than 30%, Ni: 17 to 30%, V: 0.001 to 1.0%, N: 0.10 to 0.50% and Al: not more than 0.10%, and optionally at least one element selected from at least one of the first, second and third groups of elements specified below, and the balance Fe and impurities,

(b) among the impurities, P is not more than 0.030%, S is not more than 0.005%, and Ti, Zr and Hf are not more than 0.01% respectively, and

5Cr+3.4Mn≤500N [1]

wherein the symbols of the elements represent the contents, % by mass, of the respective elements;

the first group of elements;

Mo: 0.3 to 2.33%, W: 0.3 to 6.0%, Nb: 0.001 to 0.20% and Ta: 0.001 to 0.40%;

the second group of elements;

B: 0.0001 to 0.20% and Co: 0.3 to 10.0%;

the third group of elements;

Mg: 0.0001 to 0.0050%, Ca: 0.0001 to 0.0050%, La: 0.0001 to 0.20%, Ce: 0.0001 to 0.20%, Y: 0.0001 to 0.40%, Sm: 0.0001 to 0.40%, Pr: 0.0001 to 0.40%, and Nd: 0.0001 to 0.50%.