Influences of tilt angles on microstructure and mechanical properties of 316L stainless steel parts fabricated by selective laser melting (SLM)

In order to investigate the influence of tilt angles on residual stress, the densification behavior, the microstructure and mechanical properties during selective laser melting (SLM), samples are fabricated with five tilt angles (0, 30, 45, 60 and 90 degrees) in this work. Results show that the average residual stress of samples with 0 degree arrive 400 MPa which is almost 2 times higher than that of 90 degree inclination specimen. Two mechanisms are used to explain the formation of residual stress that namely the temperature gradient mechanism (TGM) and the cool-down phase. With the increment of tilt angles, the layer thickness increases that lead to the pores and cracks accumulated. These drawbacks result in densification behavior decreases. The cracks are accompanied with pores and balling behavior. The major failure mode of tensile fracture is ductile fracture, while samples with 90 degree are fragile fracture because of defects. (paper)