Hot deformation behavior and constitutive model of GH4169 superalloy for linear friction welding process

In order to realize a better description about the plastic flow behavior in linear friction welding process of GH4169 superalloy, especially at the friction interface where rather elevated temperature and severe deformation happened, it is necessary to adopt an accurate constitutive model of GH4169 superalloy suitable for the high temperature range. The isothermal hot compression tests of GH4169 superalloy at different deformation temperatures and strain rates were designed and conducted using Gleeble-3500 thermo-simulation machine. Based on the measured flow stress-strain data, three constitutive equations were derived on the basis of the modified Field-Backofen (F-B) model, Johnson-Cook (J-C) model and strain compensated Arrhenius model, respectively. The experimental results show that the plastic flow stresses of GH4169 superalloy are significantly affected by the strain rate and temperature. The comparisons of plastic flow stress between the experimental and the calculated results based on three constitutive models show that there are great errors in the calculation on the plastic flow stress at high strain rates by using the modified F-B model and the J-C model, while the strain compensated Arrhenius model can describe exactly the plastic flow stress evolution because the coupled influences of temperature, strain and strain rate are considered. Furthermore, linear friction welding (LFW) experiment and corresponding finite element simulation based on the established constitutive equations were carried out. The comparisons of flash shape and its dimension between the simulated and experimental results indicate that the strain compensated Arrhenius model is more suitable for the LFW numerical simulation of GH4169 superalloy.