A self-consistent void-based rationale for hydrogen embrittlement

Abstract

Solely based on the failure process of metallic materials containing voids, we propose a straightforward rationale for a self-consistent void-based hydrogen embrittlement (CVHE) predictive framework that effectively captures ductile failure, hydrogen-induced loss of ductility, and most importantly, the ductile-to-brittle transition. While the coupling effect of homogenously distributed secondary voids is well-documented, the rigor of our approach lies in the precise definition of an array of equally sized and spaced secondary voids nucleated aligning with the hydrogen embrittlement mechanisms HEDE, HELP and HESIV, in the ligament between primary voids. The CVHE model can quantitatively predict the full range of embrittlement; it naturally reveals the brittle inter-ligament decohesion associated with an intrinsic lower bound of ductility, when the secondary voids are sufficiently small. Counterintuitively, our results show that ductility reduction accelerates with a decrease in the secondary void volume fraction, and that smaller voids lead to greater embrittlement.