Microstructural and Mechanical Characterization of As-Cast Co-Cr-Mo Alloys with Various Content of Carbon and Nitrogen

Abstract

Co-Cr-Mo alloys is the material used as a biomedical implant in human body. This material is widely used because they have excellent in corrosion and wear resistance. In this study, microstructure and results of tensile test that were affected by carbon and nitrogen were investigated. The specimens of Co-Cr-Mo alloy were made by investment casting. The compositions of the alloys are Co-28Cr-6Mo-0.8(Si, Mn, Fe)-0,2Ni-(0.08-0.25)C-(0-0.2)N. After that process, microstructure of the alloys is characterized by, SEM/EDX and XRD testing using bulk and electrolytic extracted specimens. The mechanical properties were determined by tensile test. The precipitate content in as-cast alloys was higher when carbon and nitrogen was added. The main precipitate formed in the specimens with variations in carbon and nitrogen is M23X6 type, π-phase, χ-phase, and σ-phase. Carbon and nitrogen promoted M23X6 type and π-phase precipitation, respectively, meanwhile χ-phase was formed in the alloys with low carbon content. The addition of carbon and nitrogen shows an increased in yield strength, tensile strength and elongation of as-cast Co-28Cr-6Mo-0.8(Si, Mn, Fe)-0,2Ni-(0.08-0.25)C-(0-0.2)N alloys.