C. L. Lach, K. M. B. Taminger, A. Schuszler II, NASA Langley Research Center, Hampton, VA; S. N. Sankaran, Lockheed Martin, Hampton, VA
The Electron Beam Freeform Fabrication (EBF3) process developed at NASA Langley Research Center was evaluated using a design of experiments approach to determine the effect of processing parameters on the composition and geometry of Ti-6-4 deposits. The effects of three processing parameters: beam power, translation speed, and wire feed rate, were investigated by varying one while keeping the remaining parameters constant. A three-factorial, three-level, fully balanced mutually orthogonal array (L27) design of experiments approach was used to examine the effects of low, medium, and high settings for the processing parameters on the chemistry, geometry, and quality of the resulting deposits. Single bead high deposits were fabricated and evaluated for 27 experimental conditions. Loss of aluminum in Ti-6-4 was observed in EBF3 processing due to selective vaporization of the aluminum from the sustained molten pool in the vacuum environment; therefore, the chemistries of the deposits were measured and compared with the composition of the initial wire and base plate to determine if the loss of aluminum could be minimized through careful selection of processing parameters. The influence of processing parameters and coupling between these parameters on bulk composition measured by Direct Current Plasma (DCP), local microchemistries determined by Wavelength Dispersive Spectrometry (WDS), and deposit geometry will also be discussed.
Summary: Electron Beam Freeform Fabrication of titanium was evaluated using a design of experiments approach for low, medium and high settings of beam power, translation speed, and wire feed rate. Vaporization of aluminum was observed in Ti6-4 deposits. Build chemistries were evaluated to determine if aluminum loss could be minimized through selection of processing parameters. The influence of each parameter on the deposit geometry and quality will be discussed.
