Effects of build direction on tensile and creep properties of 316L stainless steel produced by selective laser melting

Abstract

The influence of build direction on the mechanical properties of SS316L produced by selective laser melting was investigated. The tensile tests were performed at room temperature for vertical and horizontal specimens. Large crater-like voids were found, which are believed to be responsible for the reduced strength and premature failure of the vertical specimens, whereas the nano-sized dimples were detected on the fracture surface of the horizontal specimens. Creep tests were also conducted at 650 degrees C in the applied stress range of 149 to 226 MPa in vertical and horizontal directions. The vertical direction specimen showed better creep resistance. The micro-cracks were delayed compared with the horizontal case. Optical micrographs of the tip of the creep rupture specimens along the cross-sectional area were observed. The micro-cracks located at grain boundaries. The grain shapes orientated in the applied stress direction for the vertical specimens, and perpendicular to the applied stress direction for the horizontal specimens.