A cost-effective model for synergistic effects of microstructure and crystallographic texture on hydrogen-induced crack growth and corrosion rates in pipeline steels

Abstract

This study proposes a Cost-Effective model based on microstructure, crystallographic texture, and hydrogen (H) diffusion to evaluate H-damage in pipeline steels. H-crack growth and corrosion rates, measured using ultrasonic inspection and a Gamry electrochemical setup, were correlated with microstructure and texture. Results show that smaller ferrite grain size, lower density of $\sum 3$co-incidence site lattice boundaries (CSLB), higher densities of geometrically necessary boundaries (GNB) and random high-angle grain boundaries (RHAGB), and higher overall stored energy (E_Ave) in texture fibers increase H-trap sites and reduce effective H-diffusivity, contributing to higher H-crack growth rates. Conversely, these same factors enhance corrosion resistance by improving passivation. Secondary phases have a detrimental effect on H-crack growth and corrosion resistance, varying with size, continuity, and volume fraction of phases. The proposed model, using hyperparameter tuning, quantifies the synergistic effects of microstructure, texture, and H-diffusion on H-damage and highlights the role of ferrite grain size in mitigating H-damage in pipeline steels. Finally, finite element (FE) analysis of grain structures provided supporting observations.