Twinning behavior and hydrogen embrittlement of a pre-strained twinning-induced plasticity (TWIP) steel.

The twinning behavior and hydrogen embrittlement (HE) of a twinning-induced plasticity (TWIP) steel were investigated for different pre-strains at different strain rates. The lower pre-strain rate led to thinner twins and higher twin volume fraction. The influence of the twin characteristics on HE sensitivity was analyzed from statistical data on the evolution of surface crack characteristics during secondary straining period after cathodic hydrogen charging. Based on the ratio of crack initiation sites caused by the intersection of twins and grain boundaries, it was found that thinner twins in twin bundles of similar thickness promoted the generation of hydrogen-induced cracks (HICs). [Display omitted] • Lower strain rate led to thinner twins and higher twin volume fraction. • Specimens pre-strained with higher strain rate possessed greater resistance for HE. • The statistical evolution of secondary cracks was investigated. • Thinner twins are more likely to cause hydrogen-induced cracking. [ABSTRACT FROM AUTHOR]