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Title: Aging effects on the mechanical properties of alumina-forming austenitic stainless steels

Abstract

Isothermal aging and tensile evaluation were conducted for recently developed alumina-forming austenitic stainless steels (AFAs). Microstructural observation reveals that NiAl-type B2 and Fe{sub 2}(Mo,Nb)-type Laves phase precipitates form as dominant second phases in the austenitic matrix during aging at 750 C. At room temperature these precipitates increase the strength but decrease the ductility of the AFA alloys. However, when tested at 750 C, the AFA alloys did not show strong precipitation hardening by these phases, moreover, the elongation to fracture was not affected by aging. Fracture surface and cross-sectional microstructure analysis after tensile testing suggests that the difference of mechanical behaviors between room temperature and 750 C results from the ductile-brittle transition of the B2 precipitates. At room temperature, B2 precipitates are strong but brittle, whereas they become weak but ductile above the ductile-brittle transition temperature (DBTT).

Authors:
 [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:
979272
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Materials Science and Engineering A
Additional Journal Information:
Journal Volume: 527; Journal Issue: 7-8
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AGING; ALLOYS; DUCTILE-BRITTLE TRANSITIONS; DUCTILITY; ELONGATION; EVALUATION; FRACTURES; LAVES PHASES; MECHANICAL PROPERTIES; MICROSTRUCTURE; PRECIPITATION HARDENING; STAINLESS STEELS; TESTING

Citation Formats

Bei, Hongbin, Yamamoto, Yukinori, Brady, Michael P, and Santella, Michael L. Aging effects on the mechanical properties of alumina-forming austenitic stainless steels. United States: N. p., 2010. Web. doi:10.1016/j.msea.2009.11.052.
Bei, Hongbin, Yamamoto, Yukinori, Brady, Michael P, & Santella, Michael L. Aging effects on the mechanical properties of alumina-forming austenitic stainless steels. United States. doi:10.1016/j.msea.2009.11.052.
Bei, Hongbin, Yamamoto, Yukinori, Brady, Michael P, and Santella, Michael L. Fri . "Aging effects on the mechanical properties of alumina-forming austenitic stainless steels". United States. doi:10.1016/j.msea.2009.11.052.
@article{osti_979272,
title = {Aging effects on the mechanical properties of alumina-forming austenitic stainless steels},
author = {Bei, Hongbin and Yamamoto, Yukinori and Brady, Michael P and Santella, Michael L},
abstractNote = {Isothermal aging and tensile evaluation were conducted for recently developed alumina-forming austenitic stainless steels (AFAs). Microstructural observation reveals that NiAl-type B2 and Fe{sub 2}(Mo,Nb)-type Laves phase precipitates form as dominant second phases in the austenitic matrix during aging at 750 C. At room temperature these precipitates increase the strength but decrease the ductility of the AFA alloys. However, when tested at 750 C, the AFA alloys did not show strong precipitation hardening by these phases, moreover, the elongation to fracture was not affected by aging. Fracture surface and cross-sectional microstructure analysis after tensile testing suggests that the difference of mechanical behaviors between room temperature and 750 C results from the ductile-brittle transition of the B2 precipitates. At room temperature, B2 precipitates are strong but brittle, whereas they become weak but ductile above the ductile-brittle transition temperature (DBTT).},
doi = {10.1016/j.msea.2009.11.052},
journal = {Materials Science and Engineering A},
number = 7-8,
volume = 527,
place = {United States},
year = {2010},
month = {1}
}