Hydrogen trapping in precipitates of high-strength steel: Insights into various coherent and stress conditions
Meifeng Li, Hao Zhang, H. Henein, Jing Liu
Abstract
The phenomenon of hydrogen trapping in precipitates of steels is well-recognized, though a precise atomic level understanding remain elusive, leading to ongoing debates. This study highlights the specific roles of interfaces under various coherent conditions through first-principle calculations, incorporating local stress level, which is a novel aspect seldom explored in previous studies. It was found that coherent interfaces exhibit varying hydrogen-trapping capacities depending on their defect states, with the lowest hydrogen solution energy reaching −0.83 eV, primarily functioning as reversible traps. In contrast, derivative interfaces demonstrate superior hydrogen-trapping capacity, with hydrogen solution energy reaching −1.28 eV, classifying them as irreversible sites. Specific tensile or compressive stresses do not necessarily enhance the entrapment or release of hydrogen at precipitate interfaces; instead this depends on the characteristics of polyhedral interstices within the interfaces, with residual stress from hydrogen segregation also playing a critical role. These findings help address certain apparent controversies and advance understanding of the hydrogen embrittlement mechanism. Comprehensive investigation of H trapping characteristics of precipitates with various coherent conditions under stress. • Perfect coherent precipitates exhibit very limited H-trapping capacity. • Coherent interfaces with Es reaching −0.83 eV mainly serve as reversible traps. • Derivative interfaces with Es reaching −1.28 eV function as irreversible traps. • Various stress levels can enhance H entrapment or release at precipitate interfaces.