On the Loss of Protective Scale Formation in Creep-Resistant, Alumina-Forming Austenitic Stainless Steels at 900?aC in Air

Conference · Tue Jan 01 04:00:00 EST 2008

OSTI ID:978788

Brady, Michael P ^[1]; Yamamoto, Yukinori ^[1]; Pint, Bruce A ^[1]; Santella, Michael L ^[1]; Maziasz, Philip J ^[1]; Walker, Larry R ^[1]

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1. ORNL

A family of creep-resistant, Al2O3-forming austenitic (AFA) stainless steels was recently developed. The alloys exhibit excellent oxidation resistance up to 800 aC, but are susceptible to internal attack of Al at higher temperatures. In the present work, higher levels of Ni, Cr, Al, and Nb additions were found to correlate with improved oxidation behavior at 900 aC in air. The alloys generally appeared to be initially capable of external Al2O3 scale formation, with a subsequent transition to internal attack of Al (internal oxidation and internal nitridation) that is dependent on alloy composition. Compositional profiles at the alloy/scale interface suggest that the transition to internal oxidation is preceded by subsurface depletion of Al. Alloy design directions to increase the upper-temperature limit of protective Al2O3 scale formation in these alloys are discussed

• Research Organization: Oak Ridge National Laboratory (ORNL); Shared Research Equipment Collaborative Research Center
• Sponsoring Organization: FE USDOE - Office of Fossil Energy (FE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 978788
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AIR
ALLOYS
ALUMINIUM OXIDES
CORROSION
DESIGN
NITRIDATION
OXIDATION
STAINLESS STEELS