Download file (35.5 MB)
Download as zip (35 MB)

Collection

Citation

Description:

We have investigated the influence of the deformation temperature from 25°C (RT) to -196°C on the dislocation structures associated with strain localization phenomena in an austenitic Fe-30Mn-6.5Al-0.3C (wt.%) low-density steel by combined electron channeling contrast imaging (ECCI) and electron backscatter diffraction (EBSD) techniques. The main characteristics of the dislocation structures were evaluated on the main texture components, i.e. <111>//tensile axis, <112>//tensile axis, and <001>//tensile axis directions. Cryogenic deformation temperatures promote the inhomogeneous character of the plastic behavior due to the enhanced formation of dislocation structures associated with strain localization, namely microbands (MBs) and deformation bands (DBs). The deformation temperature has a strong influence on the thermal-assisted dislocation processes controlling the dislocation configurations and MB formation mechanisms. MB nucleation mechanism evolves from a cross-slip assisted mechanism (RT) to a slip band-assisted mechanism (cryogenic temperatures). This effect has a profound effect on the grain orientation dependence of the MB structure but does not influence its crystallographic alignment. From a mechanical standpoint, cryogenic deformation temperatures enhance strain-hardening due to the activation at moderated strain levels (0.3) of a hardening stage associated with secondary twinning. This effect is associated with the reduction of the γ_SFE at cryogenic temperatures. ECCI analysis reveals MBs and DBs have a small contribution to strain-hardening and ductility. These effects are associated with the small mechanical resistance of these dislocation structures against the advance of twin boundaries and dense dislocation layers, and the comparatively small plastic strain accommodated by these structures, respectively.

Rights:

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

Keyword: FeMnAlC low-density steels, Strain localization, Austenitic steels, Strain-hardening, Electron channeling contrast imaging (ECCI)

Date published: 2023-12-02

Publisher: Elsevier BV

Journal:

• Acta Materialia (ISSN: 13596454) vol. 264 119566

Funding:

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

MDR DOI:

First published URL: https://doi.org/10.1016/j.actamat.2023.119566

Related item:

Other identifier(s):

Contact agent:

Updated at: 2024-11-21 16:30:25 +0900

Published on MDR: 2024-11-21 16:30:25 +0900