Effect of preheating and cooling of the powder bed by laser pulse shaping on the microstructure of the TiC based cermets

For the fabrication of brittle materials like cermets through Selective Laser Melting (SLM), the pulse shaping technique has proven to be an effective and optimal way to produce cermet with no cracks. The purpose of this work is to investigate the effect of laser peak in pulse shaping as a preheating and cooling approach for the melt pool of TiC - Fe based cermet using the pulse shaping technique. Several samples were fabricated with variations in laser power and exposure time refereed as pre-pulse and post-pulse before and after the laser peak power (LPP). Microstructural and phase analyses were performed on the fabricated SLM sample using SEM and XRD to study the effect of pulse shaping with variation in exposure time and therefore energy density. Mechanical properties like microhardness were calculated and hence the effect of hardness and energy density were studied. Results indicated that preheating and cooling through laser pulse during pulse shaping has a beneficial effect on the fabrication of the crack-free brittle cermet.