Promoted Generation of Damage and Premature Fracture Due to Hydrogen-Enhanced Creation of Strain-Induced Vacancies Available to Purchase

Generation of vacancies on plastic straining is enhanced by the presence of hydrogen. The high densities of vacancies and their clusters cause damage or deterioration of crystallinity preferentially in strain-concentrated areas, leading to the formation and propagation of cracks there. Good correlations have been found between the susceptibility to hydrogen embrittlement of steels and the amount of strain-induced vacancies. The generation of damage progresses in stages preceding the onset of cracking in delayed fracture and fatigue tests. The nature of damage in various loading modes is common, and precursory damage in stress histories is carried over to later stages promoting failure. The presence of hydrogen in the final crack initiation and growth stages is not essential for embrittlement.