Microstructures and properties of porous filter parts ofselective laser melted 316L stainless steel

Objective To reveal the formation patterns and mechanisms of selective laser melted 316L stainless steel porous filter parts.

Method Both cubical and cylindrical 316L stainless steel porous filter parts with 1 mm pore size were designed and formed by selective laser melting (SLM). Microstructures and properties of these filter parts were investigated using optical microscope, scanning electron microscope and X-ray diffraction. Micro hardness of the parts was measured using microhardness tester.

Result The formed filter parts were obtained with 95% density and without defects such as pore, crack and segregation. The intra-structure was mainly composed of dendrite crystals which were vertical to the interface and grew along the epitaxy. The microstructure obtained had even layers which were metallurgically bonded. There was clear evidence of directional solidification for the formed parts.

Conclusion  The formed parts are composed of austenite, and microhardness ranges from 258 to 294 HV0.3. SLM can be used in prototyping filter parts with relatively small pore size.