Microstructural Evolution of Additively Manufactured Ti-6Al-4V During Repeated Pulsed Heating

Metal additive manufacturing (AM) is a rapidly developing processing pathway that produces components by selective fusion of feedstock material to build a specified geometry. The process results in initial rapid solidification of the deposited material followed by many thermal cycles during deposition of subsequent material layers producing a high-energy, metastable microstructure. Ti alloys are attractive for AM because the process can reduce material waste and the high cost of machining. Post-build (ex-situ) microscopy has been used observe the effect of heating profile on the final microstructure of AM Ti64. We are proposing pulsed heating measurements on AM Ti64 to monitor the evolution of the high-energy, metastable microstructure of the material at rates relevant to AM in-situ. We will extract the evolving solute chemistry, phase fractions, dislocation density, and internal stress at data rates approaching 1kHz to aid in developing predictive process/structure relationships.