High-temperature deformation characteristics and constitutive models of Inconel 625 superalloy

The isothermal compressive tests are performed to analyze the hot deformation characteristics of Inconel 625 superalloy over a wide temperature range of 1000-1150 degrees C and the strain rate scope of 0.01-10 s(-1). The hot deformation mechanisms and the impacts of deformation parameters on the thermal deformation features, are analyzed. It reveals that the true stress first rises to a maximum stress level and then progressively drops to a comparatively stable level, demonstrating apparent work-hardening (WH) and dynamic softening (DS) features. Meanwhile, the true stress swiftly rises with the reduced deformation temperature or the increased strain rate. Moreover, the almost fine and uniform grains surround the whole microstructure under relatively large true strain, elevated temperature, and depressed strain rate. Besides, three kinds of constitutive models, including the Arrhenius-type (AT) model, physical-based (PB) model, and artificial-neural-network (ANN) model, complied with the backpropagation learning (BP) and new binary particle swarm optimization (NBPSO) algorithms are developed, respectively. The correlation coefficient (R) and absolute relative error (ARE) distribution are estimated to assess the predictive abilities of the established models. It can be concluded that the maximum absolute relative errors are near 12%, 15%, and 7.2% for AT, PB, and NBPSO-BP ANN models, respectively. Meanwhile, the correlation coefficient of the NBPSO-BP ANN model is as high as 0.9983, while the corresponding ones for the AT and PB models are 0.9951 and 0.9903, respectively. Thus, the established NBPSO-BP ANN model can depict the hot deformation features of the studied superalloy precisely.

Automated summary

The hot deformation characteristics of Inconel 625 superalloy were analyzed through isothermal compressive tests at a wide range of temperatures and strain rates. The study revealed the work-hardening and dynamic softening features of the material, as well as the effects of deformation parameters. Additionally, the microstructure of the alloy showed fine and uniform grains under certain conditions. Three different constitutive models were developed to predict the thermal deformation features, and their predictive abilities were assessed.