Influence of Powder Bed Temperature on Microstructure and Post Heat Treatment of High Speed Steel AISI M50 Processed by Laser Powder Bed Fusion

摘要

Laser powder bed fusion (LPBF) is an additive manufacturing process that enables the production of complex structures without material removal. For industrial use, the mechanical properties of LPBF parts have to be at least equal to the conventionally produced parts. High carbon steels expose a tendency to create stress-induced cracks during the LPBF process. An increase in powder bed temperature often decreases the danger of crack formation during the process. In this study, the steel AISI M50 processed by LPBF at two different powder bed temperatures (room temperature and 500°C) is analyzed. The structures are compared by hardness, light microscopy (LM) and X-ray diffraction (XRD). Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) are used for a closer investigation of the microstructure and texture. The influence of the resulting LPBF structure on a possible post heat treatment is analyzed by a dilatometric determination of a time-temperature-transformation (TTT) diagram and a comparison to the behavior of the conventionally produced material.