Aging effects on the mechanical properties of alumina-forming austenitic stainless steels
- ORNL
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).
- 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:
- 979272
- Journal Information:
- Materials Science and Engineering A, Journal Name: Materials Science and Engineering A Journal Issue: 7-8 Vol. 527
- Country of Publication:
- United States
- Language:
- English
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