Wire-based laser directed energy deposition of AA7075: effect of process parameters on microstructure and mechanical properties
Mengjie Wang, Volker Ventzke, Nikolai Kashaev
Abstract
The process development for wire-based laser directed energy deposition of AA7075 is studied. Thin-wall structures are produced to investigate the process-microstructure-mechanical performance relationship. By optimizing the process parameters and building strategies, the minimal porosity level of 0.8% and 0.3% can be achieved in the continuous and discontinuous building strategies, respectively. The porosity level exhibits a primary dependence on the specific energy and a secondary dependence on the ratio between wire feed rate and laser scan speed. Thin-wall structures show an average hardness of 115 HV 0.1 . In two optimized building strategies, the ultimate tensile strength of 400 MPa is achieved without the cost of ductility (fracture strain of 9.2%). Large columnar grains with preferential orientation and the distribution of secondary phases relative to the loading direction during tensile tests contribute to superior mechanical properties.