| 摘要 |
<p>A duplex stainless steel having excellent pitting resistance and weldability and particularly a duplex stainless steel which does not form minute intermetallic compounds even in a weld heat affected zone is provided. It has a chemical composition comprising C: at most 0.03%, Si: at most 1.0%, Mn: at most 1.5%, P: at most 0.040%, S: at most 0.008%, Cr: 23.0 - 27.0%, Mo: 2.0 - 4.0%, Ni: 5.0 - 9.0%, W: greater than 1.5% up to 5.0%, N : 0.24 - 0.35%, and a remainder of Fe and impurities and satisfying the relationships PREW = Cr + 3.3 ( Mo + 0.5 W ) + 16 N€ƒis€ƒat€ƒleast€ƒ 40 €ƒand Mo + 1.1 Ni ‰¤ 12.5 Mo ˆ’ 0.8 Ni ‰¤ ˆ’ 1.6
wherein the number of coarse inclusions having the following definition observed in a cross section is at most 10 per mm 2 . Here, coarse inclusions are defined as inclusions containing at least 20 mass % of Al and having a major diameter of at least 5 micrometers.</p> |
