Abstract
The effects of Ti-6Al-4V part size on its temperature distribution during the blown-powder directed energy deposition (DED) process was investigated through dual-thermographic monitoring and a unique modeling technique. Results demonstrate that the duration of dwell times presented to be a significant contributing factor affecting the rate at which a steady-state temperature field is achieved. As a result, the longer wall took significantly more layers/time to achieve a uniform temperature profile within the wall. Maximum and average melt pool temperatures appear to be near independent of part size at a steady state. Finite element simulation results showed that a quasi-steady melt pool temperature may be unique to a layer, especially during earlier cladding process near the substrate and that the layer-wise steady melt pool was achieved within the first few seconds of track scanning. A proposed fin modeling-based temperature distribution was found to predict the thermal profile in a ‘substrate affected zone’ (SAZ) along the scan direction within 5%. A method to predict the onset of the SAZ has also been proposed. Process parameters used for the DED of component volumes are not necessarily optimal for thin-walled structures due to significantly less thermal capacity.
Additive Manufacturing and Hot-fire Testing of Bimetallic GRCop-84 and C-18150 Channel-Cooled Combustion Chambers Using Powder Bed Fusion and Inconel 625 Hybrid Directed Energy Deposition
