A geometry based approach towards improving the structural integrity of single-walled ti6al4v alloy features fabricated using laser directed energy deposition additive manufacturing

Summary

Presence of sharp turns in the deposition tool-path for Additive Manufacturing (AM) introduces heterogeneity in built-part thereby affecting structural integrity. Slower deposition speeds around turn points or corner leads to defects such as increased wall thickness, porosity, lack of fusion voids, and cracks. Such defects can be minimized by either by optimizing processing parameters or through geometry optimization. Optimizing processing parameters requires extensive and expensive set of... Show morePresence of sharp turns in the deposition tool-path for Additive Manufacturing (AM) introduces heterogeneity in built-part thereby affecting structural integrity. Slower deposition speeds around turn points or corner leads to defects such as increased wall thickness, porosity, lack of fusion voids, and cracks. Such defects can be minimized by either by optimizing processing parameters or through geometry optimization. Optimizing processing parameters requires extensive and expensive set of experiments. Furthermore, it is challenging to accurately model the process and have closed loop controls because of the impracticality to include all process parameters. This work focuses on optimizing the geometry instead of process parameters to fabricate components with minimum defects. In this work, single walled cubical Ti6Al4V shells with sharp and rounded corners were fabricated using laser Directed Energy Deposition (DED). Cross sectional and build plane coupons were extracted from each sample for microstructure and defect analysis. Results show that inclusion of rounded corners leads to consistent deposition speeds. Defect density measurements, using optical microscope, show reduction of defects from 6.8 ± 0.35% to a virtually defect-free structure for samples with rounded corners. Results indicate that consistent deposition speed around rounded corners improved homogeneity in the resulting microstructure. Show less