The influence of hydrogen on atomic binding energy, critical slip shear stress, and fatigue crack propagation rate of aluminium single crystals: Tong, Z.-X., Lin, S. and Hsiao, C.-M. Metall. Trans. A May 1989 20A, (5), 921–924

Abstract

How a corrosive environment such as a 3.5% NaCl aqueous solution would affect the transition of fatigue crack initiation mode from stage I (shear mode) cracking to stage II (normal mode) cracking was investigated, using notched specimens of HT80 and SNCM439 steels (corresponding to AISI 4340 steel).The experimental result that the transition of fatigue crack growth from stage I to stage II was accelerated in a hydrogen-related environment was discussed in terms of hydrogen induced dislocation multiplication near a crack tip. The microstructures immune to environmental damage were examined, using a precipitate-hardened steel.