Development of Materials for Metallic Direct Digital Manufacturing

The research objective of this proposal is to perform computational alloy development to enhance the Ti-6Al-4V chemistry for direct digital manufacturing (DDM). The new alloy will be designed to attain the following attributes: (1) isotropic behavior with mechanical properties on par with the upper bins of Cast+HIP Ti-6Al-4V; (2) ability to deposit builds within a window of processing conditions commonly available in the current generation of DDM equipment; (3) ability to qualify the material as per the framework described in the industry standards, AMS4999A or ASTM F42; (4) raw material cost comparable to the Ti-6Al-4V additive material. The new alloy chemistry will be targeted to attain the following: (1) refinement of grain size; (2) reduced propensity to form porosity; and (3) promote fracture toughness. Its processing parameters will be targeted to maximize basketweave microstructure throughout the deposit and to eliminate the need for post process HIP treatment. The new chemistry will be determined using analytical trial and error, which will be supported by limited deposition testing. Analytical iterations will be performed using thermodynamic modeling and process simulation. The depositions, microstructure evaluation and mechanical testing will be performed for a limited number of chemistry variations and the data will be used for the calibration of simulation input, its predictions and the demonstration of feasibility.