Computational modelling of hydrogen assisted fracture in polycrystalline materials

TL;DR

This paper introduces a novel computational model combining phase field and cohesive zone methods to simulate hydrogen embrittlement in polycrystalline metals, capturing microstructure interactions and fracture mechanisms.

Contribution

It presents a new integrated modelling framework that explicitly accounts for hydrogen-microstructure interactions and the competition between transgranular and intergranular fracture modes.

Findings

Model predicts qualitative trends in hydrogen embrittlement.

Quantitative agreement with experiments on Ni and Ni-Cu alloys.

Provides mechanistic understanding of hydrogen-induced fracture processes.

Abstract

We present a combined phase field and cohesive zone formulation for hydrogen embrittlement that resolves the polycrystalline microstructure of metals. Unlike previous studies, our deformation-diffusion-fracture modelling framework accounts for hydrogen-microstructure interactions and explicitly captures the interplay between bulk (transgranular) fracture and intergranular fracture, with the latter being facilitated by hydrogen through mechanisms such as grain boundary decohesion. We demonstrate the potential of the theoretical and computational formulation presented by simulating inter- and trans-granular cracking in relevant case studies. Firstly, verification calculations are conducted to show how the framework predicts the expected qualitative trends. Secondly, the model is used to simulate recent experiments on pure Ni and a Ni-Cu superalloy that have attracted particular interest. We show that the model is able to provide a good quantitative agreement with testing data and yields a mechanistic rationale for the experimental observations.