High cycle fatigue behaviour of AlSi10Mg alloy processed by selective laser melting technique

Abstract

ABSTRACT Selective laser melting (SLM) is progressing rapidly with promising applications in both scientific and industrial areas. AlSi10Mg is currently used in automotive and aerospace industries. While most of the existing literature on fatigue study was based on artificially made defects, various roughness levels and densified or hot isostatic pressed conditions, the present study aims to understand the high cycle fatigue (HCF) behaviour of SLMed AlSi10Mg alloy which was not subjected to any machining to remove the surface roughness. The as-built condition was high cycle fatigue tested at various stress amplitudes, and the S-N plot was drawn. OM image of the AlSi10Mg alloy in the as-built condition revealed the scan track pattern and pores in the longitudinal plane and fish scale morphology in the transverse plane. The SEM image showed a fine aluminium cell surrounded with eutectic silicon inside the melt pool. It was observed from the S-N curve that the number of cycles reduced on increasing the stress amplitude and the as-built AlSi10Mg can be used safely below 70 MPa. SEM fractography confirmed that the surface roughness, surface and subsurface pores were found to be the source of crack nucleation irrespective of the stress amplitude.