Scale dependence of the strain rate sensitivity of Twinning-Induced Plasticity steel

abstract

We report that the mechanical behavior of Twinning-Induced Plasticity steel deformed at different strain rates depends on the scale of observation. Slower-deformed samples have a higher twin density, which leads to larger flow stress measured in a macroscopic uniaxial test. When probed at the nanoscale by nano-indentation, samples pre-deformed at smaller strain rates exhibit systematically smaller hardness than samples pre-deformed at higher rates. The hardness-based nanoscale strain rate sensitivity is positive. The strain rate sensitivity measured by micro-hardness shifts to negative values as the indenter size and the probed volume increase. The effect is linked to the dislocation-twin interaction mechanism. (C) 2016 Elsevier B.V. All rights reserved.

keywords

TWIP STEELS; AUSTENITIC STEEL; DEFORMATION; TENSILE; TEMPERATURE; MECHANISMS; EVOLUTION

subject category

Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering

authors

Bintu, A; Vincze, GT; Picu, RC; Lopes, AB; Bdikin, I

our authors

acknowledgements

The authors acknowledge support from the Portuguese Foundation of Science and Technology (FCT) through project PTDC/EME-PME/116683/2010. We thank POSCO (South Korea) for providing the studied material.

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