In this paper, effect of laser scanning speed and grain size of powder of three different materials Aluminum 7075, AM100A Magnesium and UNS C85500 yellow brass are investigated. A Gaussian distribution type laser having 100-watt power and 100 m spot size is used. Simulation is carried out on a single grain, directly exposed to the laser. The prime goal of this study is to investigate the effect of different process parameters on temperature distribution in grain and capability of the specified laser to melt and fuse above mentioned material powder grain. Three different 2D models of 1µm, 2µm and 3µm grain sizes are modeled and simulated with different scanning speed 60, 100, 140, 180 and 220 mm/sec. Results are demonstrated for thermal distribution on grain along the depth. Center of the lower surface of the grain is chosen as a focus point and values are recorded and compared. The simulation results are in good agreement with the experimental work conducted in literature. For 1µm grain size melting of aluminum 7075 and AM100A Magnesium is achieved with all scanning speed except UNS C85500 Yellow Brass.