| Abstract Scope |
Many power generation technologies rely on high temperature materials for structural components. When components fail, rapid replacement parts are needed to ensure minimal disruption to the power grid. Due to its large build volume and high deposition rate, gas metal arc directed energy deposition (GMA-DED) is being considered for producing new and replacement power generation components. Haynes 282 is a gamma prime strengthened Ni-based superalloy used in many power generation applications that is designed to be highly weldable and is therefore a prime candidate for GMA-DED. In this presentation, microstructure and creep performance of GMA-DED processed Haynes 282 is discussed. A Fronius TPS 400i gas metal arc heat source was used to produce wall-shaped builds. Builds were direct one step aged to replicate the heat treating strategy developed for large Haynes 282 components. In the as-built condition, the microstructure exhibited coarse columnar grains parallel to the build direction with an average grain size of over 1 mm. After the aging heat treatment, the grain morphology was unchanged, but a heterogenous distribution of gamma prime precipitates were observed with different sizes and densities in dendrite cores and interdendritic regions. Creep testing at 760°C revealed that specimens extracted perpendicular to the build direction showed rupture times nominally equivalent to wrought Haynes 282, while specimens extracted parallel to the build direction showed creep lives greater than that of wrought. The superior creep life of GMA-DED Haynes 282 is likely due the large grain size compared to wrought counterparts, which is in alignment with predictions of creep rupture life models. The results of this work show that GMA-DED is a strong candidate to produce structural components in high temperature structural applications and may provide the rapid production capability needed to ensure reliability in the power generation infrastructure. |