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.

本研究调查了热等静压 (HIPing) 对 Al-Si-Cu-Mg 354-T6 铸造合金疲劳寿命的影响。表面孔隙度揭示了对非热等静压（非 HIPed）C354-T6 样品的疲劳寿命的主要影响，其中所有非 HIPed 样品都断裂，因为表面孔隙度充当裂纹起始点 (CIS)。发现随着孔径/周长的增加，样品疲劳寿命降低，反之亦然。热等静压技术通过消除气孔和/或减小气孔尺寸，显着提高试样的疲劳寿命，从而对 C354-T6 铸造合金的疲劳寿命产生积极影响。热等静压 (HIPed) 样品揭示了结构不规则处的裂纹起始点 (CIS)，例如滑移带和氧化膜。然而，与孔隙率相比，这些结构不规则性对样品疲劳寿命的影响较小。对于所有经过疲劳测试的样品，无论是 HIP 还是非 HIP，都观察到疲劳裂纹始于样品自由表面，而不管作为 CIS 的结构不规则类型如何。在样品表面的这一点处达到最大应力集中。