Investigation of process window for AA7075 considering effects of different wire feed directions in lateral Laser Metal Deposition

Abstract

This work addresses the influences of the feed direction of AA7075 high-strength aluminum alloy in wire-based lateral laser metal deposition (LMD). The additive manufacturing process is investigated for the deposition of thin-walled structures. The interaction between wire and laser beam as well as the evolution of the melt pool are in-situ monitored by a high-speed camera. The consequences of different feed directions are analyzed in terms of processability, surface morphology, geometry, and porosity. Besides, the appropriate process parameters for AA7075 in lateral wire LMD are also studied. A maximal relative density level of about 99.7 % can be reached. No macro-cracks on the specimen surface or inside the specimen are observed. Optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy are employed to characterize the microstructure and measure the chemical composition of specimen produced with the optimal process parameters. The plateau-like distribution of the hardness evolution and the uniform layer thickness in the middle of the thin-walled structure indicate that a stable LMD-process can be achieved.