Effect of Powder Shear Property on PBF-LB/M Powder Bed Quality of Tool Steels

Abstract

The Additive Manufacturing (AM) die & mold, which has conformal cooling channel manufactured by PBF-LB/M process, will be deliver high performance in terms of improvement of thermal fatigue. In tool steel SKD61 for AM die & mold often occurs surface crack due to abnormal surface roughness that occur during the build process. In the process, powder bed (PB) quality influenced by powder properties is one of the key factors to determine the quality of built parts. However, in terms of quantitative relationship between PB quality and powder flow-ability, there are few reports. In this study, SKD61 powders with different flow-ability (powder shear properties) due to different particle shapes were prepared and the effect of shear properties on PB roughness was investigated using the evaluation machine specialized in powder recoat process. As a result, PB roughness has a good correlation with angle of internal friction, PB roughness and PB roughness stability corresponding to powder recoat speed change showed increase with increasing angle of internal friction. It was found that it is important for PB quality to control angle of internal friction influenced by particle shapes of mean particle diameter d50 or over.