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We have investigated the influence of 101 mass ppm hydrogen content on the room
temperature deformation structure and mechanical behavior of an austenitic
Fe30Mn6.5Al0.3C (wt.%) low-density steel by several electron microscopy techniques,
such as electron channeling contrast imaging (ECCI), electron backscatter diffraction
(EBSD), and scanning electron transmission (STEM). The steel exhibits a high
hydrogen embrittlement resistance associated with a moderated increase in strength
(yield stress increase of 10%) and ductility (increase in the elongation to fracture of
8%).Analysis of the deformation structure reveals that hydrogen influences the
deformation behavior by promoting deformation mechanisms associated with
inhomogeneous plasticity (hydrogen-enhanced deformation banding (HEDB)) and
strain localization (hydrogen-enhanced microbanding (HEMB)). These deformation
mechanisms are ascribed to hydrogen-induced effects on dislocation plasticity,
resulting in macroscopic kink bands, sub-micron localized strain gradients, and
localized shear at cell blocks. We find that HEMB plays a relevant role in the
deformation behavior of sub-micron localized strain gradients by promoting plastic
relaxation and the enhanced storage of geometrically necessary dislocations within
them. These effects mitigate the activation of damage mechanisms and enhance the
strain-hardening capacity, contributing to the high HE resistance of the steel,
comparable to that of high HE-resistant fcc alloys and steels.

Rights:

• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

Keyword: Hydrogen embrittlement, FeMnAlC low-density steels, electron channeling contrast imaging, strain localization

Date published: 2024-08-26

Publisher: Elsevier BV

Journal:

• Acta Materialia (ISSN: 13596454) vol. 280 120335

Funding:

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1016/j.actamat.2024.120335

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Updated at: 2024-11-21 16:30:22 +0900

Published on MDR: 2024-11-21 16:30:22 +0900