Quantifying Equiaxed vs Epitaxial Solidification in Laser Melting of CMSX-4 Single Crystal Superalloy

Abstract The competition between epitaxial vs. equiaxed solidification has been investigated in CMSX-4 single crystal superalloy during laser melting as practiced additive manufacturing. Single-track scans were performed on a powder-free surface of directionally solidified alloy with several combinations power and scanning velocity. Electron backscattered diffraction (EBSD) mapping facilitated identification new orientations, i.e. , “stray grains” that nucleated within the fusion zone along their area fraction spatial distribution. Using high-fidelity computational fluid dynamics simulations, both temperature velocity fields melt pool estimated. This information was combined nucleation model to determine locations where highest probability occur pools. In conformance general experience metals manufacturing, as-solidified microstructure laser-melted tracks is dominated by grain growth; nevertheless, stray grains evident elongated It found that, though higher lower are generally helpful reduction grains, combination stable keyhole minimal further mitigates tracks.