Title: Orientation-selected micro-pillar compression of additively manufactured 316L stainless steels: Comparison of as-manufactured, annealed, and proton-irradiated variants

Abstract

In this work, irradiation response and deformation mechanisms of additively manufactured (AM) 316L stainless steel were studied by atomic scale characterization and micro-pillar compression. The AM 316L stainless steels were fabricated by direct energy deposition, a laser-based additive manufacturing process. Irradiation with 2 MeV protons at 360°C was performed to create ~1.8 displacements-per-atom (dpa) damage in AM 316L. Deformation behaviors of the as-manufactured, annealed, and proton-irradiated variants were studied, focusing on the effects of manufacturing-induced pores, residual stress, and irradiation-introduced defects (dislocation loops and voids). Micro-pillars were prepared from grains of pre-selected orientation, avoiding contributions of grain boundaries and allowing determination of resolved shear stress on {111} glide planes. Transmission electron microscopy was used to characterize the pre- and post-deformation microstructure. It was found that in the as-manufactured alloy variant, moving dislocations were the major deformation carrier, with noticeable blocking by fabrication-induced pores, In the annealed variant, hardness was reduced, and deformation was also accomplished by dislocation gliding. In the proton-irradiated variant, significant twinning was observed. Comparing measured resolved shear stress and predicted critical stress for dislocation dissociation, we conclude that irradiation hardening became high enough to activate twinning. Therefore, the deformation mechanism changes from dislocation gliding to twinning. Themore » study is important for both processing optimization and performance evaluation of AM alloys for reactor applications.« less

Authors:

Shiau, Ching-Heng ^[1]; Sun, Cheng ^[2]; McMurtrey, Michael ^[2]; O'Brien, Robert ^[2]; Garner, Frank A. ^[3]; Shao, Lin ^[3]

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+ Show Author Affiliations

1. Texas A & M Univ., College Station, TX (United States); Boise State Univ., ID (United States); Center for Advanced Energy Studies, Idaho Falls, ID (United States)
2. Idaho National Lab. (INL), Idaho Falls, ID (United States)
3. Texas A & M Univ., College Station, TX (United States)

Publication Date:

Wed Apr 20 00:00:00 EDT 2022

Research Org.:

Georgia Institute of Technology, Atlanta, GA (United States); Idaho National Laboratory (INL), Idaho Falls, ID (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Nuclear Energy (NE)

OSTI Identifier:

1878579

Alternate Identifier(s):

OSTI ID: 1865626; OSTI ID: 1895151

Grant/Contract Number:  

NA0003921; AC07-05ID14517

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Nuclear Materials

Additional Journal Information:

Journal Volume: 566; Journal ID: ISSN 0022-3115

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Irradiated metals; Irradiation effect; Deformation; Deformation twinning; Compression test