|About this Abstract
||10th International Symposium on Superalloy 718 and Derivatives (2023)
||Superalloy 718 and Derivatives
||Microstructural and Tensile Properties Evolutions of Direct-aged Waspaloy Produced by Wire Arc Additive Manufacturing
||Marjolaine Sazerat, Azdine Nait-Ali, Lucie Barot, Alice Cervellon, Inmaculada Lopez-Galilea, Dominique Eyidi, Anne Joulain, Patrick Villechaise, Jonathan Cormier, Sebastian Weber, Roland Fortunier
|On-Site Speaker (Planned)
The microstructure and tensile properties of direct aged Waspaloy manufactured using wire arc-based Cold Metal Transfer (CMT) have been investigated. Samples were exposed to temperatures ranging from 700░C to 900░C, for up to 96 hours. In the as-deposited condition, pronounced chemical segregation is inherited from the process, leading to heterogeneous γ' precipitation between dendrite cores and interdendritic spacings. Precipitate size and distribution were measured in both areas for each heat treatment, and a diffusion-controlled coarsening behavior following the LSW theory was observed for temperatures above 760 ░C. Activation energies were calculated. Tensile tests at room temperature were carried out on the additive alloy pre- and post-aging, but also on wrought sub-solvus and super-solvus treated material for reference. Results showed that heat treatment significantly increased the yield strength and ultimate tensile strength of the CMT samples, of up to +340 MPa compared to the as-built conditions. Elongation, however, decreased from 40-45% to 16-28%. Direct aged CMT Waspaloy exhibited a similar behavior to that of wrought super-solvus Waspaloy, due to their large grains (~200-250 Ám). Anisotropy in tensile properties was estimated by calculating the ratio of properties for horizontal and vertical specimens. Finally, the formation of secondary phases was assessed. Thermodynamic calculations predicted the formation of M23C6, η and σ in interdendritic spacings at thermodynamic equilibrium. By using Electron diffraction patterns and Energy-Dispersive X-ray Spectroscopy in TEM, intergranular (Cr,Mo)23C6 secondary carbides decorating grain boundaries and near (Ti,Mo)C primary carbides in the interdendritic spacings were observed to nucleate and grow.
||Definite: At-meeting proceedings