Hot deformation behavior and dynamic recrystallization of GH690 nickel-based superalloy

Abstract

In this study, hot compression tests of GH690 nickel-based superalloy were carried out on a Gleeble3180 thermo-mechanical simulator with strain rates of 0.1-2s−1 and the temperature range of 950–1200 °C. The true stress-strain curves can reflect the internal relationship between true stress and thermo-mechanical behavior, and the evolution law of internal microstructure. According to the true stress-strain curves obtained from the tests, it can be obtained that temperature and strain rate have a great influence on the hot deformation behavior of GH690 alloy. To study this effect, the Arrhenius-type constitutive equation is used to characterize the relationship between various factors and predict the stress state. The material constants in the Arrhenius-type constitutive equation were determined by linear fitting of the experimental data, where the activation energy Q is about 425 kJ mol−1. Furthermore, the microstructure evolution of GH690 alloy was also analyzed, dynamic recrystallization (DRX) critical strain model, Avrami DRX volume fraction model and DRX grain size model were also established. The constitutive model and DRX dynamic model established in the study are imported into the commercial finite element software Deform-3D to verify the established model. The research results show that the prediction results of the numerical simulation agree well with the test. The combination of the established model and numerical simulation is very useful for studying the hot deformation of the alloy.