Influence of process parameters and build platform preheating on defect occurrence in L-PBF Inconel 718

This study investigates the effect of process parameters — specifically laser power, scanning speed, and build platform preheating — on the quality and defect formation in laser-powder bed fusion Inconel 718 components, with the aim of identifying optimal combinations of parameters for achieving high-quality components. Three different batches of samples were fabricated at different preheating temperatures: 80°C, 300°C, and 500°C. The alloy was investigated in terms of density, using gas pycnometry and optical microscopy, revealing that 300°C preheating yielded the largest number of specimens with optimal quality, whereas 500°C resulted in lower densities and larger defects. Scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy showed the formation of a fine cellular microstructure with oxide inclusions of varying morphologies and compositions, and solidification cracks, in particular in samples printed with the lowest preheating temperature. Finally, a mechanical characterization based on the hardness measurements indicated a general decrease in hardness with increasing preheating temperature.