Effect of Build Orientation and Size on the Amount of the Defects of Stainless Steel 316L Parts Made by Selective Laser Melting Process

Many parameters,including scanning strategy,speed,power,etc,have an impact on the mechanical and physical properties of the parts made by the selective laser melting process.Correct and optimal selection of these parameters prevents defects such as porosity,incomplete fusion gaps and cracks in the parts of the manufacturing process.Despite all the advantages of the selective laser melting process,the creation of defects directly affects the mechanical properties and fatigue resistance of the parts negatively. In this research,the impact of zero,45,and90degree build orientations,the effect of changing the size of the parts on mechanical properties such as tensile and shear strength,fracture strain,and the number of defects investigated.The built parts were subjected to tensile and shear tests,and the fracture area was examined using SEM and the existing defects identified.The tensile test results showed that larger samples have higher tensile strength than smaller samples.Moreover,higher tensile strength and lower fracture strain were observed in samples made in zerodegree orientation.The results of the shear test also showed that the strength of the shear stress for the small and large samples made in all orientations is almost the same,and the highest shear strain of failure is related to the samples made in the orientation of 45degrees independent of the dimensions.The SEM results also showed that the amount and distribution of spherical holes and fusion gaps in large samples made at90degrees is more than in samples made at 0and45degrees