Effect of melt superheating on solidification microstructure and mechanical properties of K424 superalloy

• Optimal melt superheating at 1,650°C for 5 min yields the finest grain size (949 μm) and SDAS (25.38 μm) in K424 superalloy, enhancing mechanical properties. • Melt treatment temperature and duration significantly influence undercooling, elemental segregation, and solidification microstructure, with higher temperatures reducing segregation. • Room-temperature tensile strength and stress rupture life are markedly improved by specific melt treatment conditions, with 1,650°C/5 min providing superior strength and 1,600°C/10 min balancing strength and stability. • The study provides practical guidance for optimizing melt treatment parameters to refine microstructure and improve performance of K424 superalloy castings.