Influence of the annealing and defects on the VHCF behavior of an SLM AlSi10Mg alloy

In the paper, the influence of the annealing temperature on the Very High Cycle Fatigue (VHCF) of AlSi10Mg specimens produced through selective laser melting (SLM) is experimentally assessed. VHCF tests at 20 kHz are carried out on Gaussian specimens subjected to a heat treatment suggested by the system supplier (heating for 2 hours to 320 degrees C and air cooling) and to a heat treatment proposed by the authors (heating for 2 hours to 244 degrees C and air cooling). The defects originating failure and the conditional P-S-N curves are compared. Experimental results show that an annealing temperature of 320 degrees C induces the spheroidization of the Si network, which enhances the ductility but has a negative effect on the VHCF response. On the contrary, by reducing the heating temperature to 244 degrees C, the original as-built microstructure is not altered and the minimization of the residual stresses permits to enhance the VHCF response.