The Effect of Lack-of-Fusion Porosity on Fatigue Behavior of Additive Manufactured Titanium Alloy

Abstract

As we know, the fatigue performance of AM materials is highly associated with the microstructure. The fatigue performance of additive manufacture alloy materials of Ti-6Al-4V is investigated in this study. Considering the hysteresis energy, a damage evolution equation has been advanced. The material parameters in damage evolution equation are obtained with fatigue experimental data. A homogenizing model with reflecting microstructures is established. Two types of defects, gas porosity and lack-of-fusion porosity, are discussed. The mean fatigue crack initiation lives of additive manufactured Ti6Al4V with different orientations are predicted by the present method. The computational results are agreement well with the experimental data. The effect of lack-of-fusion porosity density on the fatigue performance of AM materials is studied. The fatigue lives of AM materials with different lack-of-fusion porosity size are evaluated. This present method represents the effect of the microdefect on the fatigue performance, with the effect of anisotropic damage and strain.