Role of deformation on the hydrogen trapping in the pearlitic steel.

Improving hydrogen embrittlement resistance is a prerequisite for expanding the application of high-strength steels. A high-strength deformed pearlitic steel exhibits excellent hydrogen embrittlement resistance presumably because strong hydrogen trapping sites induced by deformation prevent hydrogen accumulation at potential crack initiation sites. This work reports the conclusive identification of the strong hydrogen trapping site in the deformed pearlitic steels. Thermal desorption spectroscopy showed a distinct hydrogen desorption peak at high temperature of ∼ 600 K solely in the deformed pearlite. Scanning transmission electron microscopy and atom probe tomography analyses revealed that the deformation resulted in strain localization at the ferrite/cementite interfaces, together with the formation of a large number of dislocations, leading to the strong segregation of deuterium, a natural isotope of hydrogen, at the interface. Therefore, hydrogen trapping in the deformed pearlitic steels is attributed to the strained ferrite/cementite interface. [Display omitted] [ABSTRACT FROM AUTHOR]