Experimental investigation on the influence of build direction in wire arc additively manufactured AA7075 nano-TiC metal matrix composites

Abstract

This study presents a systematic experimental investigation into the influence of build direction on the mechanical behavior of Wire arc additive manufactured AA7075 nano-TiC metal matrix composites by using Cold metal transfer technique. Radiographic inspection confirmed defect-free deposition. Single-wall structures were fabricated at a wire feed rate of 8 m/min, and a travel speed of 150 mm/min and Arc Length Correction −5% (15.3 V). Tensile specimens were extracted along the X-direction, Y-direction, and at 45° to the X–Y plane. The results revealed pronounced anisotropy, with X-direction specimens exhibiting the highest performance, achieving a maximum Ultimate tensile strength of 730 MPa, Elongation of 20.5%, and Microhardness values ranging from 77 to 104 HV across deposited layers. These properties are superior to those of unreinforced AA7075 as cast alloys, which typically exhibit elongation in the range of 4%–6%, hardness 60–90 HV, and UTS 280 MPa. Fractographic analysis revealed a predominantly ductile failure mode with equiaxed dimples across all orientations. The findings provide quantitative insight into build-direction effects in WAAM aluminum matrix composites, contributing to improved understanding and optimization of WAAM deposition strategies for aerospace applications.