Atom probe tomography observation of hydrogen distribution in steels
 

The presence of hydrogen in steels causes catastrophic embrittlement. However, the difficulties to observe hydrogen solution in steels and to associate its influence with the failure of certain microstructures limit our understanding of the origin of this hydrogen-induced problem. We thus developed an experimental protocol of ‘cryogenic atom probe tomography’ that allows direct observation of hydrogen distribution in steels. Following ex-situ electrolytic hydrogen charging, we observed hydrogen distribution around crystal defects, nanosized carbide precipitates, as well as cementite/ferrite interface which is an important feature in steel pipes. These efforts lead to the mechanistic understanding of hydrogen trapping and hydrogen embrittlement, pathing the development of the high-strength alloys that have intrinsic resistance to hydrogen embrittlement and can be used for essential applications such as automotive and the transmission and storage of hydrogen fuel.