Surface hardness and bending fatigue properties of dental cobalt-chromium alloys fabricated by selective laser melting at different heat-treatment temperatures

Methods: Co-Cr alloy specimens fabricated by SLM were divided into four groups according to the heat-treatment temperature: Con, FT750, FT850, and FT950.Bending fatigue tests were performed under a cyclic load of 13 N at 5 Hz for 30,000 cycles.Surface hardness was measured using a Vickers hardness tester at six designated locations.Results: No fracture occurred in any group after 30,000 cycles.The FT950 group showed the highest displacement, whereas the FT750 group showed the lowest displacement.After heat treatment, surface hardness increased significantly, with the FT850 group showing the highest hardness value.Statistical analysis revealed significant differences among all groups (p<0.05). Conclusion:Heat treatment significantly affected the mechanical properties of SLM-fabri- cated Co-Cr alloys.The FT850 group exhibited the most favorable balance between hardness and fatigue resistance, suggesting that a heat-treatment temperature of 850°C may be considered a favorable condition for dental Co-Cr alloy frameworks in terms of hardness and deformation behavior.