Microstructural, Mechanical, and Tribological Characterization of Selective Laser Melted CoCrMo Alloy under Different Heat Treatment Conditions and Hot Isostatic Pressing

A deep knowledge of material properties is fundamental to obtain high-performance medical implants realized with CoCrMo alloy manufactured by selective laser melting (SLM), even more so when considering that heat treatments (HTs) are often necessary to refine the microstructure, eliminate residual stress, and improve mechanical properties. To this aim, herein, SLM CoCrMo alloy samples are produced in six different treatment conditions: as built (AB), four different vacuum HTs, and hot isostatic pressing (HIP). Modifications to microstructure, hardness, tensile behavior, and wear resistance are then investigated. Results reveal that vacuum HTs and HIP have different effects on microstructure and types of defects with respect to the AB condition. Thus, proper selection of the treatment is mandatory to improve specific mechanical properties, such as strength, ductility, hardness, or tribological response. In this context, it is confirmed that the choice of an appropriate HT allows SLM CoCrMo to reach the target mechanical properties set by international standards for applications in the medical field, such as dentistry or orthopedics.