Abstract
The present study investigated the influence of hot isostatic pressing (HIPing) on the fatigue life of Al-Si-Cu-Mg 354-T6 casting alloy. Surface porosity revealed the major impact on the fatigue life of non-hot isostatic pressed (non-HIPed) C354-T6 samples, where all non-HIPed samples fractured because surface porosity acted as crack initiation sites (CIS). It was found that as the pore size/perimeter increases, the sample fatigue life decreases and vice versa. HIPing technology revealed a positive impact on the fatigue life of C354-T6 casting alloy through eliminating porosity and/or reducing the size of the pores such that the specimens' fatigue life was significantly increased. The hot isostatic pressed (HIPed) samples revealed crack initiation sites (CIS) at structure irregularities such as slip bands and oxide films. These structure irregularities, however, displayed less effect on the samples' fatigue life, as compared to porosity. With regard to all fatigue-tested samples either HIPed or non-HIPed, the fatigue crack was observed to initiate at the sample free surface, regardless of the type of structure irregularities acted as CIS. The maximum stress concentration was attained at this point of the sample surface.