HYDROGEN-ENHANCED LOCALIZATION OF PLASTICITY IN AN AUSTENITIC STAINLESS-STEEL

Microscopic observations and the results of static strain aging, stress redilatation, and strain rate change tests on 310s stainless steel foils, with and without hydrogen, have been presented to complement the stress-strain curves in a previous article. The hydrogen-free specimens showed minute yield points during static strain aging, while the hydrogen-containing specimens demonstrated ''preyield microstrain.'' Thermal activation analysis of the strain rate change and stress relaxation plots led to the conclusion that the activation area for dislocation motion is decreased by hydrogen. Microstructural examination with the scanning electron microscope (SEM) revealed extensive strain localization, while transmission electron microscopy (TEM) studies showed microtwinning and austenite faulting in hydrogenated specimens tested at room temperature. The relation of hydrogen-induced changes in plastic deformation to hydrogen embrittlement is discussed.