The influence of hydrogen on plasticity in pure iron-theory and experiment

TL;DR

This study combines experiments and modeling to reveal how dissolved hydrogen dramatically alters dislocation structures and promotes localized plasticity in pure iron, advancing understanding of hydrogen embrittlement.

Contribution

It introduces a new self-consistent kinetic Monte Carlo model that predicts hydrogen-induced microstructural changes observed experimentally in pure iron.

Findings

Hydrogen charged specimens show unique dislocation patterns absent in uncharged metal.

The model successfully predicts the observed microstructure changes.

Hydrogen enhances localized plasticity mechanisms in pure iron.

Abstract

Tensile stress relaxation is combined with transmission electron microscopy to reveal dramatic changes in dislocation structure and sub structure in pure alpha iron as a result of the effects of dissolved hydrogen. We find that hydrogen charged specimens after plastic deformation display a very characteristic pattern of trailing dipoles and prismatic loops which are absent in uncharged pure metal. We explain these observations by use of a new self consistent kinetic Monte Carlo model, which in fact was initially used to predict the now observed microstructure. The results of this combined theory and experimental study is to shed light on the fundamental mechanism of hydrogen enhanced localised plasticity.