Nowadays, full-field microstructural simulation is of primary importance in predicting grain size evolution during forming processes and heat treatments (HT). Our latest developments in the Level-Set Finite Element [1] commercial software DIGIMU® enables us to take into account second phase particles and their evolution during heat treatments. These precipitates block the grain boundary (GB) motion through the Smith-Zener pinning (SZP) mechanism [2,3,4].

This study investigates the behavior of two superalloys during several subsolvus treatments: Aubert&Duval‘s AD730 (only 𝛾′ precipitates) and Safran’s N19 (one population of 𝛾′ precipitates and one population of prior boundaries particles coming from powder metallurgy). For both, the dissolution kinetics of the primary precipitates was analyzed through an extensive range of experimental observations. Then, a phenomenological model was established to describe their area fraction and size kinetics by combining Thermo-Calc simulations and a Johnson-Mehl-Avrami-Kolmogorov model [5].

For the alloys, full-field grain growth simulations combined with the phenomenological particles evolution models are in good agreement with the experimental results in the transient and stable regimes. In the case of N19, near solvus heat treatments, where the primary 𝛾′ particles are completely dissolved, the grain size is still controlled by the oxides coming from the used powder metallurgy route [6]. These results are very promising concerning the possibility to optimize subsolvus heat treatments of superalloys via numerical simulations.