Depending on the strength of the steel, hydrogen embrittlement, measured as the relative reduction of area of a smooth specimen in monotonic tensile testing, also increases (shown herein). The figure emphasizes the relative reduction of area in hydrogen as a function of ultimate tensile strength of some ferritic steels. Reprinted from Gangloff and Somerday, Gaseous Hydrogen Embrittlement of Materials in Energy Technologies: The Problem, its Characterisation and Effects on Particular Alloy Classes (Woodhead Publishing, 2012).8 Copyright 2012 Woodhead Publishing.