Wire-arc additive manufacturing of a novel high-performance Al-Zn-Mg-Cu alloy: Processing, characterization and feasibility demonstration

Wire-arc additive manufacturing (WAAM) is a feasible technology for manufacturing of metallic components of medium complexity with a high deposition rate. Manufacturing of aluminum alloys for e.g. structural components of the aero plane fuselage by this technology has been impeded by the unavailability of high-performance alloys with good processability and low susceptibility to hot cracking. Therefore, a novel alloy system has been developed based on the Al-Zn-Mg-Cu system and successfully processed by WAAM without the occurrence of any hot cracks. Heat treatment strategies were developed allowing for optimum mechanical properties. A homogeneous grain structure was observed with few elongated grains. Upon heat treatment, the formation of T phases was verified with a precipitate size in the range of similar to 10 nm. These are responsible for the observed pronounced age-hardening response of this alloy. An isotropic proof stress of up to similar to 340 MPa and a fracture strain of up to similar to 11% are evidence of the high quality of the WAAM deposited material allowing for an extended use of these alloys for advanced applications. Finally, the applicability and processability of the alloy was proven by fabrication of a motorcycle piston.