Steel alloy for ferritic steel having excellent creep strength and oxidation resistance at elevated usage temperatures

US9080230B2 · kind B2 · utility

Assignee

• VALLOUREC DEUTSCHLAND GmbH · DE

Inventors

• Bernd Hahn · Springe, DE
• Joachim Konrad · Goldkronach, DE
• Andre Schneider · Moissac, FR
• Charles Stallybrass · Mülheim an der Ruhr, DE

Key dates

• Filing date: Jul 3, 2009
• Grant date: Jul 14, 2015
• Expiry date: Oct 28, 2030

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/12014
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A steel alloy with excellent creep strength and corrosion resistance that is ferritic at usage temperatures above 620° C. has the following chemical composition (in wt. %): C≦1.0%; Si≦1.0%; Mn≦1.0%; P max. 0.05%; S max. 0.01%; 2≦Al≦12%; 3≦Cr≦16%; 2≦Ni≦10% and/or 2≦Co≦10%, where 2≦Ni+Co≦[% Cr]+2.07×[% Al]>=0.95×([% Ni]+[% Co]); N max. 0.0200%. The remainder is iron with steel production-related impurities. Optionally, one or more elements of V, Ti, Ta, Zr, Nb, Mo and W, as well as one or more elements of Hf, B, Se, Y, Te, Sb, La and Zr with a cumulative content of <0.1% can be added. The steel structure includes uniformly distributed coherent precipitates based on a chromium-stabilized (Ni, Co)Al—B2 intermetallic ordered phase.