Shrinkage Porosity and Microstructure Control via Casting-Module-Driven Optimization in Ni-based Superalloy Castings

Controlling shrinkage porosity and microstructural inhomogeneity in complex Ni-based superalloy castings remains challenging. This study proposes a shrinkage control model via Casting module simplification, quantifying the effects of pouring temperature, shell mold temperature, and pouring rate. The results indicate that increasing the pouring temperature from 1500 to 1550 °C reduced the shrinkage porosity volume by 3.08 cm³ (0.097%), while raising the shell mold temperature by 50 °C suppressed this defect volume by 2.10 cm³ (0.055%). A prioritized strategy was established: first increase the pouring temperature, which offers a volume reduction of 0.62 cm³ per 10 °C, and then the shell mold temperature, which provides a reduction of 0.42 cm³ per 10 °C. Under optimized parameters (1550 °C, 900 °C, 5.2 kg/s), shrinkage volume decreases from 15.54 cm³ to 2.13 cm³, validated by experimental casting. The as-cast microstructure comprises γ matrix and MC carbides, coarsening dendritic γ and transforming MC from fine particles to coarse lamellae at grain boundaries under slower cooling rates.