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Title: Development of Alumina-Forming Austenitic Stainless Steels

Abstract

This paper presents the results of the continued development of creep-resistant, alumina-forming austenitic (AFA) stainless steel alloys, which exhibit a unique combination of excellent oxidation resistance via protective alumina (Al2O3) scale formation and high-temperature creep strength through the formation of stable nano-scale MC carbides and intermetallic precipitates. Efforts in fiscal year 2009 focused on the characterization and understanding of long-term oxidation resistance and tensile properties as a function of alloy composition and microstructure. Computational thermodynamic calculations of the austenitic matrix phase composition and the volume fraction of MC, B2-NiAl, and Fe2(Mo,Nb) base Laves phase precipitates were used to interpret oxidation behavior. Of particular interest was the enrichment of Cr in the austenitic matrix phase by additions of Nb, which aided the establishment and maintenance of alumina. Higher levels of Nb additions also increased the volume fraction of B2-NiAl precipitates, which served as an Al reservoir during long-term oxidation. Ageing studies of AFA alloys were conducted at 750 C for times up to 2000 h. Ageing resulted in near doubling of yield strength at room temperature after only 50 h at 750 C, with little further increase in yield strength out to 2000 h of ageing. Elongation was reduced on ageing;more » however, levels of 15-25% were retained at room temperature after 2000 h of total ageing.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shared Research Equipment Collaborative Research Center
Sponsoring Org.:
FE USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
969016
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 23rd Annual Conference on Fossil Energy Materials, Pittsburgh, PA, USA, 20090512, 20090514
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; CARBIDES; CREEP; ELONGATION; LAVES PHASES; MAINTENANCE; MICROSTRUCTURE; OXIDATION; STAINLESS STEELS; TENSILE PROPERTIES; THERMODYNAMICS; YIELD STRENGTH

Citation Formats

Brady, Michael P, Yamamoto, Yukinori, Bei, Hongbin, Santella, Michael L, and Maziasz, Philip J. Development of Alumina-Forming Austenitic Stainless Steels. United States: N. p., 2009. Web.
Brady, Michael P, Yamamoto, Yukinori, Bei, Hongbin, Santella, Michael L, & Maziasz, Philip J. Development of Alumina-Forming Austenitic Stainless Steels. United States.
Brady, Michael P, Yamamoto, Yukinori, Bei, Hongbin, Santella, Michael L, and Maziasz, Philip J. Thu . "Development of Alumina-Forming Austenitic Stainless Steels". United States.
@article{osti_969016,
title = {Development of Alumina-Forming Austenitic Stainless Steels},
author = {Brady, Michael P and Yamamoto, Yukinori and Bei, Hongbin and Santella, Michael L and Maziasz, Philip J},
abstractNote = {This paper presents the results of the continued development of creep-resistant, alumina-forming austenitic (AFA) stainless steel alloys, which exhibit a unique combination of excellent oxidation resistance via protective alumina (Al2O3) scale formation and high-temperature creep strength through the formation of stable nano-scale MC carbides and intermetallic precipitates. Efforts in fiscal year 2009 focused on the characterization and understanding of long-term oxidation resistance and tensile properties as a function of alloy composition and microstructure. Computational thermodynamic calculations of the austenitic matrix phase composition and the volume fraction of MC, B2-NiAl, and Fe2(Mo,Nb) base Laves phase precipitates were used to interpret oxidation behavior. Of particular interest was the enrichment of Cr in the austenitic matrix phase by additions of Nb, which aided the establishment and maintenance of alumina. Higher levels of Nb additions also increased the volume fraction of B2-NiAl precipitates, which served as an Al reservoir during long-term oxidation. Ageing studies of AFA alloys were conducted at 750 C for times up to 2000 h. Ageing resulted in near doubling of yield strength at room temperature after only 50 h at 750 C, with little further increase in yield strength out to 2000 h of ageing. Elongation was reduced on ageing; however, levels of 15-25% were retained at room temperature after 2000 h of total ageing.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2009},
month = {1}
}

Conference:
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