Microstructural performance, mechanical properties and correlation of tensile strength of multi-material structure fabricated via wire plus arc additive manufacturing

This study investigates the fabrication of a multi-material (MM) wall using titanium alloys (Ti-2 and Ti-9) via tungsten inert gas (TIG) welding-based wire plus arc additive manufacturing (WAAM). The objective is to understand the metallurgical characteristics, mechanical performance and simulation validation of MM walls. Detailed microstructural analysis, including EBSD, revealed epitaxial grain growth, phase redistribution and stabilization of β-Ti at the Ti-2/Ti-9 interface due to localized thermal cycles and solute partitioning. Mechanical testing showed that the MM-interface exhibited superior hardness, tensile strength and impact toughness compared to wrought alloys. Finite element simulations using the Johnson–Cook damage model closely matched experimental tensile results, with less than 1% error, confirming the reliability of the approach. The novelty of this study lies in addressing MM Ti WAAM structures unlike conventional single-alloy studies while also providing experimental–numerical correlations and identifying the strengthening role of interface microstructural transformations. These findings enhance understanding of MM WAAM systems for aerospace, automotive and biomedical applications.