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Acta Materialia, Volume 60, Issues 13–14, August 2012, Pages 5182-5189
Akihide Nagao, Cynthia D. Smith, Mohsen Dadfarnia, Petros Sofronis, Ian M. Robertson
Department of Mechanical Science and Engineering, University of Illinois, 1206 W. Green St., Urbana, IL 61801, USA
Steel Products Research Department, Steel Research Laboratory, JFE Steel Corporation, 1-1 Minamiwatarida-cho, Kawasaki-ku, Kawasaki, Kanagawa 210-0855, Japan
Department of Materials Science and Engineering, University of Illinois, 1304 W. Green St., Urbana, IL 61801, USA
International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Fukuoka 819-0395, Japan
Abstract
The microstructure associated with the hydrogen-induced features “flat” and “quasi-cleavage” on the fracture surface of a lath martensitic steel has been visualized in a transmission electron microscope by using focused-ion beam machining to extract samples perpendicular to the fracture surface. Beneath both hydrogen-induced fracture surfaces there is direct evidence, in the form of intense slip bands and destruction of lath boundaries, for significant plasticity. These observations are considered in terms of the fundamental hydrogen embrittlement mechanisms, and the conclusion is reached that the failure is driven by a hydrogen-enhanced and plasticity-mediated decohesion mechanism.
