Abstract:The microstructure of an alloy is affected intensively by the cooling process. To figure out the inherent relation between the cooling rate and microstructure of an advanced nickel-based superalloy, experimental and numerical studies on the cooling process were conducted. Specifically, the measurement was performed concerning both the temperature of the specimen during the end-quench test and the size of the secondary γ′ phase of the specimen after that. The heat transfer coefficient of the quenched surface was determined by the inverse heat transfer method for simulation. The results show that the cooling rate of the quenched surface exceeds 1574 K/min. Based on the averaged cooling rate obtained from the simulation and the measured size of the secondary γ′ phase, an empirical correlation in a double logarithmic relationship between them is proposed. The relationship is verified by the experiment with specified cooling rates.

Key words: end-quench test; numerical simulation; cooling rate; heat transfer coefficient; nickel-based superalloy