Creep and Tensile Properties of Waspaloy Produced by Wire Arc Additive Manufacturing

The creep and tensile behavior of Waspaloy, a γ′-strengthened nickel-based superalloy, processed by Wire Arc Additive Manufacturing using Cold Metal Transfer (WAAM–CMT) was investigated for repair applications. Mechanical properties of the bulk material were assessed up to 850 °C in both the As-Built (AB) and Post-Weld Heat Treated (PWHT) conditions, with particular attention to the effect of the loading direction. The AB microstructure consisted of large columnar grains with ultra-fine γ′ precipitates and serrated boundaries pinned by carbides, providing considerable hardening despite being out-of-equilibrium. PWHT promoted γ′ coarsening and secondary carbide formation, enhancing yield and tensile strength to levels comparable with coarse-grained wrought Waspaloy. A shallow heat-affected zone (300 to 600 µm) was identified, and digital image correlation analysis of strain localization confirmed the good mechanical strength of the interface. Tensile testing revealed weak anisotropy (< 9 pct) in strength, with AB samples exhibiting higher ductility. PWHT was particularly efficient at elevated temperatures, enabling properties equivalent to fine-grained wrought Waspaloy. Creep testing showed in situ aging and an initial contraction in the AB material. PWHT improved creep resistance at 700 °C to 750 °C but degraded performance at 800 °C to 850 °C, with strong anisotropy in creep life and strain at rupture. These findings establish WAAM–CMT as a promising repair technique for aircraft components.