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Title: Effect of boron and carbon addition on microstructure and mechanical properties of the aged gamma-prime strengthened alumina-forming austenitic alloys [Effect of boron and carbon addition on microstructure and mechanical properties of the aged gamma-prime alumina-forming austenitic alloys]

Here, the goal of this work was to understand the effects of aging at 800 °C on the microstructures and mechanical properties of two recently-developed AFA stainless steels based on Fe-14Cr-32Ni-3Nb-3Al-2Ti (wt.%), one of which contained small additions of boron and carbon. To that end both the size distributions and growth kinetics of the B2, Laves phase, L1 2 precipitates present were quantified. While the lattice parameter, morphology, size and coarsening behavior of the L1 2 precipitates was the same in both AFA alloys, the B and C enhanced the grain boundary coverage by both Laves phase and B2-NiAl precipitates, but suppressed their coarsening. These interstitial additions also suppressed the formation of twins and discontinuous precipitation, which were observed in the B and C-free material. It is shown that the yield strength at 700 °C is largely controlled by the size of the L1 2 precipitates, with the largest strengthening effect obtained after aging for 2.4 h for both AFA alloys. Longer aging time led to a loss of strength mainly due to the coarsening of the L1 2 precipitates.
 [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [2]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Dartmouth College, Hanover, NH (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
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Additional Journal Information:
Journal Volume: 90; Journal Issue: C; Journal ID: ISSN 0966-9795
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
36 MATERIALS SCIENCE; aging; alumina-forming austenitic stainless steels; boron; coarsening; gamma prime; grain boundaries; intermetallics; precipitation
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