Effects of Thermal Processing on the Multiscale Mechanical Behavior of Laser Directed Energy Deposited CoCrMo Alloy

This study investigates the effects of thermal processing on the mechanical properties of CoCrMo alloys fabricated via laser directed energy deposition, using various heat treatment strategies. Microstructural analysis revealed a transition from a columnar grain structure and carbide‐rich grain boundaries in the as‐built (AB) sample to a microstructure with a high density of annealing twins in samples heat‐treated at 1200°C. Notably, the 1200SHT condition subjected to a short annealing treatment, exhibited an almost full‐solutionized structure. The AB condition exhibited an ultimate tensile strength (UTS) of around 1350 MPa, with an elongation of almost 25%. In contrast, the 1200CT and 1200SHT samples demonstrated lower yield strengths in lieu of significantly improved ductility, reaching failure elongation levels close to 60%. Despite the reduced yield strength, the consistent strain‐hardening behavior led to a moderate UTS reaching almost 1200 MPa. Additionally, while the pop‐in phenomenon was observed in all conditions during nanoindentation, its delayed onset after heat treatment indicates improved ductility and suppression of strain‐induced martensitic transformation.