Grain refinement and property improvements of Al–Zn–Mg–Cu alloy by heterogeneous particle addition during wire and arc additive manufacturing

Abstract

Al–Zn–Mg–Cu alloys are widely used in large-scale structural components of the aerospace industry, but research on wire and arc additive manufacturing (WAAM) of Al–Zn–Mg–Cu alloys is lacking. This research focused on grain refining of Al–Zn–Mg–Cu alloys by adding TiN particles during WAAM. The WAAM component was filled with equiaxed grains and the grain orientation became more random because the coarse columnar grains were eliminated. The average grain size was reduced from a value of 459 μm to a value of 104 μm. Heterogeneous nucleation by TiN particles was the main grain refining mechanism, and the TiN particles located along the grain boundaries also helped prevent grain growth. The horizontal and vertical elongations were increased by 160% and 98%, respectively, because of grain refinement; whereas the horizontal tensile strength was increased by 38.1%. The enhanced mechanical properties were mainly attributable to grain refinement and weakening of the texture strength.