Mathematical modeling of crystal growth and microstructure formation in laser powder deposition of single crystal superalloy

Abstract

The effects of process parameters on crystal growth and microstructure development during the laser powder deposition of single-crystal superalloy were studied through mathematical modeling and experimental approaches. A self-consistent three-dimensional mathematical model was developed to predict the temperature distribution, molten pool formation and solidification in laser powder deposition of single-crystal superalloy. The effects of the governing processing parameters of laser powder deposition, i.e. laser power, scanning peed, powder feeding rate on the resulting crystal growth orientations and microstructures are studied. Laser powder deposition experiments with single crystal alloy Rene N5 were conducted to verify the computational results of the deposited microstructure. The results indicate that processing parameters have profound influence on the molten pool shape and the resulting crystal growth and epitaxial microstructure in the deposit. For the (001)/[100] crystal orientation in substrate, the height ratio of epitaxial columnar dendrite along (001)/[100] crystallographic orientation increases with the increase of scanning speed and powder feeding rate, while it can be optimized with the variance of laser power. The results of simulation and experiments agree well. This work contributes to the understanding of microstructure formation and providing a fundamental basis for optimization of laser powder deposition process of single crystal superalloy.The effects of process parameters on crystal growth and microstructure development during the laser powder deposition of single-crystal superalloy were studied through mathematical modeling and experimental approaches. A self-consistent three-dimensional mathematical model was developed to predict the temperature distribution, molten pool formation and solidification in laser powder deposition of single-crystal superalloy. The effects of the governing processing parameters of laser powder deposition, i.e. laser power, scanning peed, powder feeding rate on the resulting crystal growth orientations and microstructures are studied. Laser powder deposition experiments with single crystal alloy Rene N5 were conducted to verify the computational results of the deposited microstructure. The results indicate that processing parameters have profound influence on the molten pool shape and the resulting crystal growth and epitaxial microstructure in the deposit. For the (001)/[100] crystal orientation in substrate, ...