Patent ID: 9512509
Filing Date: 2016-12-06
CPC Classification: C21D,C22C

Claim Text:
1. A duplex stainless steel having a chemical composition consisting of, by mass %: C: not more than 0.03%, Si: not more than 0.3%, Mn: not more than 3.0%, P: not more than 0.040%, S: not more than 0.008%, Cu: 0.2 to 2.0%, Ni: 5.0 to 6.5%, Cr: 23.0 to 27.0%, Mo: 2.5 to 3.5%, W: 1.5 to 4.0%, and N: 0.24 to 0.40%, the balance being Fe and impurities, wherein a σ phase susceptibility index X represented by the following Formula (1) is not more than 52.0; a strength index Y represented by the following Formula (2) is not less than 40.5; and a pitting resistance equivalent PREW represented by the following Formula (3) is not less than 40: where a symbol of each element in the Formulas (1), (2), and (3) denotes a content (mass %) of the element, wherein an impact value regulated by JIS Z 2242 (2005) after aging at 900° C. and 600 seconds is not less than 18 J/cm