Influence of Solution Treatment on Microstructure and Properties of CoCrMo Alloy

CoCrMo alloy was prepared by using vacuum induction melting technology, and solution treatment of the alloy was carried out at 1200 ℃ for 4 h. The microstructure and properties of the as-cast and solution-treated CoCrMo alloys were comparatively analyzed. The results show that the dendritic microstructure of the as-cast CoCrMo alloy is coarse, the primary precipitates M₂₃C₆ and σ phases are rich in chromium, molybdenum and carbon, which are unevenly distributed and form a network structure, leading to inferior mechanical properties. During solution treatment, the dendritic microstructure of the cast alloy is eliminated, and the primary precipitates M₂₃C₆ and σ dissolve, forming a supersaturated solid solution, and the elements such as chromium and molybdenum do not have sufficient time to segregate and precipitate during air cooling,resulting in the formation of uniformly distributed, fine and regularly shaped M₂₃C₆phases. Compared with those of the alloy in cast state, the tensile strength of the soluble CoCrMo alloy decreases, but the plasticity increases greatly.