Integrated Melt Pool Geometry and Microstructure Control for Additive Manufacturing

A critical concern for additive manufacturing process qualification is obtaining consistent microstructures and desirable mechanical properties.  This research explores the idea that indirect control of microstructure is possible through direct control of key melt pool dimensions.  In this talk the approach is applied to wire feed electron beam AM processes.  Modeling results over a wide range of process variables are presented to illustrate the approach, initially for the control of solidification microstructure (prior beta grain size and morphology) in single bead deposits of Ti-6Al-4V.  Experimental results are presented that are consistent with the model predictions.  The connection between microstructure and melt pool dimensions is further explored for an additional deposit geometry and other microstructural characteristics.  By linking microstructure control to melt pool geometry, which can be monitored in-situ, the number of tests and microstructural examinations needed for process qualification can be significantly reduced.  This approach can also be the basis for advanced approaches to thermal imaging feedback control systems.