Publication Date
2010
Document Type
Thesis
Committee Members
Jack Beuth (Committee Member), Srikanth Bontha (Committee Member), Nathan Klingbeil (Advisor)
Degree Name
Master of Science in Engineering (MSEgr)
Abstract
Laser and electron beam-based additive manufacturing of Ti-6Al-4V are under consideration for application to aerospace components. A critical concern for these processes is the ability to obtain a consistent and desirable microstructure and corresponding mechanical properties of the deposit. Based on the Rosenthal solution for a moving point-heat source, recent work has developed simulation-based process maps for the thermal conditions controlling microstructure (grain size and morphology) in beam-based deposition of semi-infinite geometries, where a steady-state melt pool exists away from free-edges. In the current study, the Rosenthal solution is modified to include the effects of free-edges. This is accomplished by the superposition of two point-heat sources approaching one another, with the line of symmetry representing the free-edge. The result is an exact solution for the case of temperature-independent properties. Dimensionless results for melt pool geometry, solidification cooling rate and thermal gradient are determined with MATLAB, and plotted as a function of distance from the free-edge. Finite element analysis is used to verify results for 2-D and 3-D geometries in both small-scale and large-scale (higher power) processes. Results are further plotted on solidification maps to predict trends in microstructure for Ti-6Al-4V. Results suggest that melt pool geometry is more sensitive to free-edges than solidification microstructure, particularly for small-scale processes. This is an important result for process developers.
Page Count
85
Department or Program
Department of Mechanical and Materials Engineering
Year Degree Awarded
2010
Copyright
Copyright 2010, all rights reserved. This open access ETD is published by Wright State University and OhioLINK.
