Comparison of fatigue behaviour and fracture toughness of cobalt chromium alloy fabricated by casting and selective laser melting methods

Abstract

Co-Cr alloys are most commonly used base metal alloy in dentistry for the fabrication of many types of metallic substructures. They gained popularity due to their good mechanical properties and low cost. There are different techniques for fabrication of Co-Cr alloys which includes casting and DMLS technique. However, change in the fabrication techniques showed variation in mechanical properties. Forty Co-Cr samples each were made from two different techniques, Casting and DMLS. Fracture toughness was done with charpy’s impact test machine and fatigue behaviour test was done with nano universal testing machine. The samples were later observed under stereo electron microscope to assess the kind of failure. Unpaired t test revealed that there was statistically significant difference between two different groups. The mean difference of fracture toughness in Casting group was higher when compared with DMLS group. The number of fatigue cycles were higher in DMLS group than the casting group. Within the limitations of this in vitro study, casting group showed higher fracture toughness when compared to DMLS group, whereas fatigue limit was higher in DMLS group than casting group.