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]

Journal Article · 03 July 2017 · Intermetallics

DOI: https://doi.org/10.1016/j.intermet.2017.06.011 · OSTI ID:1421962

Hu, Bin ^[1]; Trotter, Geneva ^[2]; Wang, Zhangwei ^[2]; Chen, Si ^[1]; Cai, Zhonghou ^[1]; Baker, Ian ^[2]

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1. Argonne National Lab. (ANL), Argonne, IL (United States)
2. Dartmouth College, Hanover, NH (United States)

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, L1₂ precipitates present were quantified. While the lattice parameter, morphology, size and coarsening behavior of the L1₂ 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 L1₂ 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 L1₂ precipitates.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); USDOE
• Grant/Contract Number: AC02-06CH11357; DEFG2612FE0008857
• OSTI ID: 1421962
• Alternate ID(s): OSTI ID: 1550409
• Journal Information: Intermetallics, Vol. 90, Issue C; ISSN 0966-9795
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English