FIG. 16.

Topography (top row) and SKPFM (bottom three rows) images of (a) annealed, (b) cold rolled, and (c) recrystallized ferritic steel as a function of time. The samples were charged electrochemically with hydrogen, covered with a palladium detection layer, and tested in a nitrogen environment. In Ref. 229, the authors used SKPFM, TDS, and electron microscopy to identify and analyze hydrogen trapping sites in a ferritic steel subjected to annealing, cold rolling, and recrystallization. Comparing the SKPFM results to those of a known technique allowed elucidation of the behavior of different traps with a finer degree. As desorption was only observed from some inclusions by SKPFM, and TDS results suggest trapping vacancies, it was argued that desorption was dominated by the hydrogen released from vacancies at the oxide–matrix interface, as opposed to trapping and desorption from the oxide inclusions. Reprinted from Krieger et al., Acta Mater. 144, 235 (2018).²²⁹ Copyright 2018 Elsevier.