Influences of Different Selective Laser Melting Machines on the Microstructures and Mechanical Properties of Co–Cr–Mo Alloys

Dental prostheses have been fabricated using various selective laser melting (SLM) machines; however, the impact of the type of machine on the microstructure and mechanical properties of Co–Cr–Mo alloys remains unclear. In this study, we prepared samples using two SLM machines (the small M100 and mid-sized M290) with different beam spot sizes (40 and 100 µm, respectively). The microstructures and tensile properties of the heated (1150 °C for 60 min) and as-built samples were evaluated. The grain sizes of the M100 samples were smaller than those of the M290 samples due to the small beam spot size of the M100 machine. Both heated samples exhibited recrystallized equiaxed grains; however, the amount of non-recrystallized grains remaining in the M290 sample exceeded that in the M100 sample. This suggests that the M100 samples recrystallized faster than the M290 samples after heating. The elongation of the M100 samples was higher than that of the M290 samples in the as-built and heated states, owing to the smaller grain size of the M100 samples. A comparison of the M100 and M290 SLM machines indicated that the M100 was suitable for producing dental prostheses owing to its good elongation and rapid recrystallization features, which shorten its post-heat-treatment duration.