Development of porous 316L stainless steel with novel structures by selective laser melting

The selective laser melting of a metallic/inorganic blended powder system consisting of 316L stainless steel powder and NH4HCO3 powder was performed. The SEM characterisation showed the formation of a honeycomb-like porous structure possessing unusually micrometre scaled pores (similar to 2 to similar to 5 mu m), with the addition of 4.0 wt-%NH4HCO3 powder using a high laser power of 800 W. The EDX and XRD analyses testified that the obtained porous structure was stainless steel with high chemical purity. The developing mechanism of such a novel microcellular structure under various processing conditions was addressed. It shows that the cooperative action between bubbles escaping kinetics and metallic matrix solidification kinetics, accounts for the formation of the honeycomb porous configuration. The effects of component ratio and main processing parameters on the development of porous structures were also assessed.