Influence of microstructure on the crack propagation and corrosion resistance of Al–Zn–Mg–Cu alloy 7150

This paper described the effect of the grain structure on the initiation and propagation of fatigue crack and exfoliation corrosion in the 7150-T6 alloy. The 7150-T6 alloy extrusions exhibited different grain structure from the surface to the midsection. The regions close to the surface had smaller grain size and exhibited better resistance to initiation and propagation of fatigue crack. Exfoliation developed rapidly in the midsection of the extrusion as a result of the coarse elongated grains. On the surface of extrusion, no exfoliation corrosion occurred. The crack initiation and propagation and severity of exfoliation were shown to be related to the grain size and shape of the material.