Influence of Laser Power and Scan Speed on the Formation of Hot Cracks during the Processing of High-speed Steel HS2-2-2 by Laser Powder Bed Fusion

Abstract

The manufacturing of high-speed steel (HSS) components using the laser powder bed fusion (LPBF) process could create an unprecedented combination of the materials’ mechanical properties and the design freedom enabled by the process to unlock new applications, such as milling heads with functionally optimized cooling channels. However, the processing of HSS with the LPBF process shows high susceptibility to cracking. This contribution aims to reduce hot cracking for the processing of HS2-2‑2 by investigating the influences of preheating temperature, laser power, and scan speed on the formation of hot cracks. The density and melt pool geometry of the produced parts are measured to further examine the relationship between the processing conditions and the resulting properties. The influence of various process parameters on the formation of hot cracks can be demonstrated. Further investigation shows a relation between hot cracking and the melt pool geometry. With a narrow and shallow melt pool, influenced by laser power and scan speed, the number of hot cracks can be reduced.