Influence of laser powder bed fusion parameters on microstructure and mechanical properties of Co–Cr dental alloy

Abstract

This research investigates the impact of three process parameters of Laser Powder Bed Fusion (LPBF) - laser power, scanning speed, and base plate preheating temperature on the structure and mechanical properties of the EOS CoCr SP2 dental alloy. The LPBF process was used to fabricate dental Co–Cr alloy specimens for microstructural analysis and mechanical properties testing. Light and electron microscopy were used to determine microstructural parameters, including porosity, inclusions, and cracks. The material's chemical composition was analysed by EDS, while XRD and EBSD methods were used to determine the presence of microstructural phases and the crystallographic orientation of individual grains. The mechanical properties were evaluated through a static tensile test (Rp0.2, ε), a toughness test (KVa), and a three-point bending test to determine the flexural strength (Rms). In the microstructure, differences were observed that reflected statistically significant differences in mechanical properties (one-way analysis of variance (ANOVA) and Scheffé post hoc test (α = 0.05)) Using the base plate preheating temperature ϑp = 310 °C with a constant scanning speed v = 900 mm/s in combination with increasing laser power P from 160 W to 250 W the proportion of porosity decreased while the mechanical properties of toughness (KVa) and flexural strength (Rms) increase to maximum values.