Thermal Process Maps for Controlling Microstructure in Laser Deposited Materials

The ability to predict and control microstructure in laser deposited materials requires an understanding of the thermal conditions at the onset of solidification. To this end, the focus of this work is the development of thermal process maps relating solidification cooling rate and thermal gradient (the key parameters controlling microstructure) to laser deposition process variables (e.g., laser power and velocity). Results presented herein are based on the Rosenthal solution for a moving point heat source traversing an infinite substrate. Ongoing work includes the effect of a distributed laser power through superposition of the Rosenthal solution, while the effects of finite geometry, temperature dependent properties and latent heat of transformation are included through thermal finite element modeling of the laser deposition process.