Duplex ferritic austenitic stainless steel

US11566309B2 · kind B2 · utility

Assignee

• Outokumpu Oyj · FI

Inventors

• James Oliver · Fjärdhundra, SE
• Erik Schedin · Uppsala, SE
• Rachel Pettersson · Norrtälje, SE

Key dates

• Filing date: Jun 12, 2014
• Grant date: Jan 31, 2023
• Expiry date: Jun 12, 2034

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/005
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Disclosed is a duplex ferritic austenitic stainless steel of 40-60 volume % ferrite and 40-60 volume % austenite, with improved cold workability and impact toughness. It contains less than 0.07% carbon (C), 0.1-2.0% silicon (Si), 3-5% manganese (Mn), 19-23% chromium (Cr), 1.1-1.9% nickel (Ni), 1.1-3.5% copper (Cu), 0.18-0.30% nitrogen (N), optionally molybdenum (Mo) and/or tungsten (W) according to the formula (Mo+½W)<1.0%. It optionally contains 0.001-0.005% boron (B), up to 0.03% of each of cerium (Ce) and/or calcium (Ca), with the balance being iron (Fe) and impurities where the chromium equivalent (Creq) and the nickel equivalent (Nieq): 20<Creq<24.5 and Nieq>10, where Creq=Cr+1.5Si+Mo+2Ti+0.5Nb Nieq=Ni+0.5Mn+30(C+N)+0.5(Cu+Co).