Macrodimensional accuracy of Ti6Al4V parts manufactured by wire-feed high layer thickness continuous laser directed energy deposition

Abstract

This paper presents a detailed study on the dimensional accuracy of Ti6Al4V parts manufactured by the wire feed laser directed energy deposition process as compared to the design data before any postprocessing, as the majority of the reported research is focused on the mechanical and microstructural properties of the manufactured parts. Due to the large layer thickness (1.2 mm) and high material deposition rate (15 mm/s), smaller rectangular samples were susceptible to more dimensional inaccuracies. Most of the samples have larger dimensions than the design data, which is favorable for postprocessing. Special consideration should be given to the Z axis as the top layer has the most curves on the periphery of the samples due to shrinkage upon cooling. Depositing the material along the periphery of the present layer at the start of each layer minimized the overflow of the molten alloy when the laser is near the edges of the model in each layer. Upon further inspection using an optical microscope and scanning electron microscope analysis, surfaces voids were observed. Only ∼0.5 mm was required to remove from each side to obtain a minimal crack-free flat surface. The microhardness of the samples ranged from 313.64 to 346.17 HV.