Effect of hydrogen charging on the microstructure of duplex stainless steel

The influence of hydrogen on the microstructure of austenitic-ferritic stainless steel was investigated. Thin foils of this steel subjected to cathodic hydrogen charging were examined using transmission electron microscopy. The effect of hydrogen charging time on the microstructure evolution was studied. The characteristic evolution of the α and γ phases microstructures were observed. The microstructural transformations in the γ phase consist of an increase of the number of stacking faults and dislocation density. Another specific type of structural changes was revealed in the α phase by electron diffraction. The hypothesis of ferrite strong grain refinement was considered. It is suggested that the character of the interphase boundary affects the mode of cracking. Possible explanations of the effects observed are discussed