The effect of NiB additive on surface morphology and microstructure of 316L stainless steel single tracks and layers obtained by SLM

- Selective laser melting (SLM) of 316L and 316L-1wt.%NiB powders
- Presence of satellites, fragments and pores in SLM of pure 316L tracks and layers
- Addition of NiB (1 wt.%) particles minimized the presence of microstructural defects.
- Smooth melting in 316L-NiB alloy achieved for lower values of building parameters.
- Lower surface roughness in 316L-NiB alloy due to low melting boride-based eutectics

Stainless steel (316L) powder and mixed 316L-1wt.%NiB powders were melted by laser irradiation. Laser employed was pulsed, millisecond Nd:YAG laser system. The relationship between major process variables - average laser power, laser scan speed, number of spots, pulse energy, pulse duration, pulse frequency - of selective laser melting, and their effect on the structure of single tracks and single layers in case of 316L and 316L-NiB alloys has been investigated. The morphology, macro- and microstructure of laser melted samples were characterized by digital camera and by scanning electron microscope with an energy dispersive X-ray spectrometer. Surface roughness of the layers was measured using optical profilometer. It was determined that the addition of NiB to 316L stainless steel powder provides much better surface quality and wider set of parameters for successful melting.

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