Influences of hydrogen on deformation and fracture behaviors of high Zn 7XXX aluminum alloys

Hydrogen degrades the mechanical properties of high strength 7XXX aluminum alloys in two ways: (i) degrades the mechanical properties by hydrogen embrittlement, and (ii) partitioned into micropores as molecular hydrogen and make contributions to ordinary ductile fracture. The multifaceted effects of hydrogen on the mechanical properties of high Zn content 7XXX aluminum alloys during deformation and fracture is studied by using synchrotron X-ray microtomography. Our results have revealed that the hydrogen susceptibility has increased with increasing the Zn amount. High concentration of hydrogen was induced by the EDM wire eroder. This high concentrated hydrogen induces quasi-cleavage fracture and restricts the growth of micropores during ductile deformation. The threshold concentration of hydrogen ahead of the crack tip for the nucleation of quasi-cleavage feature was estimated to be .