Near surface modification affected by hydrogen interaction: Global supplemented by local approach

The current study is centered on elastic-plastic solid interaction with hydrogen. Here, the environment is free hydrogen, from either external or internal origins providing as such aggressive effects. In this context, near surface displacement occurred, beside microcracking onset or growth, significant interfacial weakening, as critical forms of mechanical degradation. Metastable austenitic stainless 316L steel was selected, in order to provide a comprehensive study on bulk surfaces. Global findings on hydrogen effects were supplemented by nanoscale information. Only for the nanosection, Ti/Cu thin films were also included, namely an additional small-volume case. Samples have been charged with hydrogen under low fugacity conditions and the outcoming effects have been sorted out by mechanical response tracking assisted by contact mechanics methodology. Nanoindentation and continuous scratch tests were utilized supplemented by Scanning Probe Microscopy (SPM) visualization. Local resolution provided remarkable input to the global findings, in terms of dislocation nucleation aspects, near surface modification, plastic localization and microfracture onset. In thin layers, the effective work of the adhesion was reduced indicating significant degradation that could be expressed quantitatively. Global/ local benefits of the stainless steel system under study made it possible to apply multiscale models describing complex micro-mechanical processes.