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Title: The effects of cold work on the microstructure and mechanical properties of intermetallic strengthened alumina-forming austenitic stainless steels

In order to achieve energy conversion efficiencies of >50 pct for steam turbines/boilers in power generation systems, materials are required that are both strong and corrosion-resistant at >973 K (700 °C), and economically viable. Austenitic steels strengthened with Laves phase, NiAl and Ni3Al precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The microstructure and microchemistry of recently developed alumina-forming austenitic stainless steels have been characterized by scanning electron microscopy, transmission electron microscopy, and synchrotron X-ray diffraction. Different thermo-mechanical treatments were performed on these steels to improve their mechanical performance. These reduced the grain size significantly to the nanoscale (~100 nm) and the room temperature yield strength to above 1000 MPa. Lastly, a solutionizing anneal at 1473 K (1200 °C) was found to be effective for uniformly redistributing the Laves phase precipitates that form upon casting.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [1]
  1. Dartmouth College, Hanover, NH (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
OSTI Identifier:
1207045
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science
Additional Journal Information:
Journal Volume: 46A; Journal Issue: 8; Journal ID: ISSN 1073-5623
Publisher:
ASM International
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 24 POWER TRANSMISSION AND DISTRIBUTION alumina-forming austenitic stainless steels; intermetallic precipitates; thermomechanical treatment; Laves-phase