Mechanism of Hydrogen-related Failure I

Abstract

Major models so far proposed on the mechanism of hydrogen embrittlement are critically reviewed. The theories are classified into two streams, brittle or ductile fracture in nature. The theories for brittle fracture are triggering by internal pressure, surface energy reduction and lattice decohesion. The ductile fracture models presented here are hydrogen-assisted cracking, hydrogen-enhanced localized plasticity, adsorption-induced dislocation emission and autocatalytic effect on plastic instability. Interconnections of hydrogen embrittlement and stress corrosion cracking are also presented. Particular attention is paid on experimental conditions and assumptions on which the theories are based.