A numerical study on effects of randomly distributed subsurface hydrogen pores on fretting fatigue behaviour of aluminium AlSi10Mg

Abstract

Abstract The successful construction of additively manufactured metallic components for safety-critical applications requires a thorough understanding of the associated tribo-mechanical properties such as fretting fatigue phenomenon. Various porosity formations mechanisms occur in selective laser melting of aluminium alloys. The internal porosity is forming because of the powder and printing process itself. These pores, which act as internal micro defects, result in premature fatigue crack initiation and subsequent fatigue failure. In this study, numerical simulation technique is used to investigate the effects of randomly distributed hydrogen pores on the fretting fatigue response of additively manufactured aluminium AlSi10Mg part. From the simulation results it has been found that at the high-stress levels the fretting fatigue primary variables such as tangential and frictional shear stresses along with slip amplitude are slightly affected by the distribution of porosity close to the contact interface. 60% of the fatigue crack initiation locations are detected at the pore sites (killer defects) underneath the contact interface near the contact edge. The killer defect size varies between 32 μm and 60 μm in diameter. Eventually, the fretting fatigue lifetime decreases for 92% of simulated case studies and higher scatter results are observed at the high-stress levels compared to the low stresses.