Build position-based dimensional deviations of laser powder-bed fusion of stainless steel 316L

This study investigates the effect of position on build-plate on the dimensional deviations for stainless steel 316 L samples made by laser powder-bed fusion. To understand the effect of sample position on the build-plate (substrate) with respect to shrinkage and dimensional deviation, 36 samples in a 6 x 6 array were printed with three repetitions. The value of the diameter was measured at 10 points along the vertical axis in the perpendicular and parallel directions to the flow of the assisted gas. The results of the experiment show that there is shrinkage in both directions with respect to the gas flow. However, the extent of deviation in the perpendicular direction to the gas flow is greater compared to the parallel diameters for the samples. This can be related to the pressure of assisted gas and the difference in cooling rate corresponding to the position of the samples on the building substrate. The hypothesis is proved by conducting further experiments regulating the amount of gas flow by adjusting the individual nozzle for the gas flow to the build chamber. The reason for these deviations is speculated to be related to the rheology of the melt pool. This research could lay a solid foundation for the future development of a compensation strategy to nullify the effect of shrinkage and dimensional deviations on parts made using the laser powder-bed fusion technique. The results of shrinkage of the columns appear to suggest that there is an effect on the circularity from the assisting gas.