Multi-Variate Analysis of Laser Powder Bed Fusion with 90-μm Layer Thickness of Ni-Based Superalloy Haynes 282

Abstract

Laser powder bed fusion (PBF-LB) processing of Haynes 282 using a layer thickness of 90-μm is studied for process capability and feasibility for increased productivity. To optimize the build rate while producing metallurgically sound parts, the effect of laser parameters on the resulting melt pool dimensions and porosity are analyzed. In a previous study, individual parameters such as laser power, scan speed and hatch distance and combination have been studied. In this study, three levels of hatch distance have been investigated while varying power and speed to same extent at all three (3) hatch distance. Similarly, the highest power level has been studied for the effect of speed and hatch distance. The melt pool dimensions, and porosity were measured in the plane parallel to the build direction. Comparison of measured responses with individual parameters provides partial trends of melt pool dimensions and porosity. It was observed that high power and/or low speed and low hatch distance increase the melt pool dimensions and reduce porosity until keyhole mode is reached. Variation of two parameters while keeping the third parameter constant was found to affect porosity due to the transition from lack of fusion type defects to keyhole porosities. The presence of dominant type of defect is identified using average feret ratio, which is the ratio of maximum length to minimum length across parallel surfaces inside a defect. It is found successful to use the combination study of process parameters and resultant type of defects to map the process to achieve minimal defects is identified for 90-μm layer thickness, through the combination study of process parameters and the resultant type of defects.