Search

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. [ABSTRACT FROM AUTHOR]

Investigation of the selective laser melting (SLM) process, using finite element method, to understand the influences of laser power and scanning speed on the heat flow and melt-pool dimensions is a challenging task. Most of the existing studies are focused on the study of thin layer thickness and comparative study of same materials under different manufacturing conditions. The present work is focused on comparative analysis of thermal cycles and complex melt-pool behavior of a high layer thickness multi-layer laser additive manufacturing (LAM) of pure Titanium (Ti) and Inconel 718. A transient 3D finite-element model is developed to perform a quantitative comparative study on two materials to examine the temperature distribution and disparities in melt-pool behaviours under similar processing conditions. It is observed that the layers are properly melted and sintered for the considered process parameters. The temperature and melt-pool increases as laser power move in the same layer and when new layers are added. The same is observed when the laser power increases, and opposite is observed for increasing scanning speed while keeping other parameters constant. It is also found that Inconel 718 alloy has a higher maximum temperature than Ti material for the same process parameter and hence higher melt-pool dimensions. [ABSTRACT FROM AUTHOR]