Microstructure and Mechanical Properties of AM Builds

Additively manufactured metal components are subjected to heat and melting cycles that are vastly different from more conventional manufacturing processes whether cast, welded, or wrought. The selective melting of a small amount of material on a larger, relatively cool body, leads to solidification rates that are hundreds to thousands of time faster than observed in casting. This rapid solidification results in much different microstructures for AM parts versus traditional manufacturing, which in turn, results in differing mechanical properties for AM components. This study describes the microstructure, hardness, yield and ultimate tensile strengths, ductility, and fatigue strength of AM Inconel 625, Ti-6Al-4V, and Austenitic stainless steel. Comparisons are made for both microstructures and properties between traditional and additively manufactured components. Discussion is provided on the challenges of linking processing, microstructure, and the resulting material properties, and the high variation of AM properties that may occur even when using identical materials, machines, and processing parameters.