Modeling the Hydrogen Redistribution at the Grain Boundary of Misoriented Bicrystals in Austenite Stainless Steel

Abstract

Hydrogen embrittlement, as one of the major concerns for austenitic stainless steel, is closely linked to the diffusion of hydrogen through the grain boundary of materials. The phenomenon is still not well understood yet, especially the full interaction between hydrogen diffusion and the misorientation of the grains. This work aimed at the development of a robust numerical strategy to model the full coupling of the hydrogen diffusion and the anisotropic behavior of crystals in 316 stainless steel. A constitutive model, which allows easy incorporation of crystal orientation, various loading conditions, and arbitrary model geometries, was established by using the finite element package ABAQUS. The study focuses on three different bicrystal models composed of misoriented crystals, and the results indicate that the redistribution of hydrogen is significant closely to the grain boundary, and the redistribution is driven by the hydrostatic pressure caused by the misorientation of two neighboring grains. A higher elastic modulus ratio along the tensile direction will lead to a higher hydrogen concentration difference in the two grains equidistant from the grain boundary. The hydrogen concentration shows a high value in the crystal along the direction with stiff elastic modulus. Moreover, there exists a large hydrogen concentration gradient in a narrow region very close to the grain boundary to balance the concentration difference of the neighboring grains.

Special Issue “Extreme Mechanics in Multiscale Analyses of Materials”

“…The papers included in this Special Issue deal with a broad spectrum of interests in analytical, computational, and experimental studies on extreme types of material behaviour. The included papers encompass many areas of extreme mechanics modelling including: a strength investigation using detailed microfractography analysis of fractures formed during static tensile tests of steel Armstal 550 [ 1 ], a study on the effect of NTO content on the properties of an HMX-based cast-PBX (polymer bonded explosive) [ 2 ], the dependency of contact length on cutting speed and other variables performed by the optical method in cutting processes [ 3 ], bone molecular models at the nanoscale [ 4 ], molecular models of bones at the nanoscale, the characterisation of composites’ mechanical behaviour at low temperatures [ 5 ], the diffusion of hydrogen atoms through the grain boundaries of materials, the failure properties of batteries under axial forces [ 6 ], the deformation and failure properties of Ni lithium batteries [ 7 ], the effect of material heterogeneity on the environmentally assisted cracking growth rate of Alloy 600 for safe-end welded joints [ 8 ], the high strain yielding of the additive manufacturing of Inconel 625 through laser melting [ 9 ], the effect of the yield strength distribution of welded joints on the crack propagation path and the crack mechanical tip field [ 10 ], the effect of mechanical heterogeneity on strain and stress fields at crack tips of SCC in dissimilar metal welded joints [ 11 ], and the characterisation of mechanical heterogeneity in dissimilar metal welded joints [ 12 ].…”