Hot deformation and processing maps of Inconel 690 superalloy

The hot deformation behavior of Inconel 690 has been investigated by means of hot compression tests in the temperature range of 950–1200 °C and strain rate range of 0.001–10 s−1. The results show that the maximum stress decreases with decreasing strain rate and increasing temperature, and the activation energy is about 380.215 kJ/mol. Processing maps developed on the basis of experimental data and using the principles of the dynamic materials model exhibited two domains. The first domain occurs in the temperature range of 970–1120 °C and strain rate range of 0.03–3.3 s−1, with a peak efficiency of power dissipation of 0.39. The second domain occurs in the temperature range of 1150–1200 °C and strain rate range of 0.003–0.1 s−1, with a peak efficiency of power dissipation of about 0.37. Microstructural observations revealed that the full dynamic recrystallization (DRX) occurred in these two domains. In the first domain, the undissolved carbides assisted in nucleating DRX and restricted the coarsening of the full DRX grains and the refined grains were obtained. A small regime of flow instability was noticed at low temperature and high strain rate.