Hot Forging Behavior of Inconel625 Superalloy Based on Processing Map

Abstract

The hot forging behavior of Inconel625 superalloys was studied in hot compression tests by the thermal mechanical simulator with Gleeble-3800. The testing conditions were that the maximum strain was 0.8, the deformation temperatures were 950, 1000, 1050, 1100, 1150, 1200 °C, and the strain rates were 0.1, 1, 5, 10, 50, 80/s. The constitutive equation was developed based on true stress (σ)-strain (e) curves, and the activation energy of Inconel625 superalloy under hot compression was about 679.6 kJ/mol. The processing map was developed based on experiment data and the dynamic material model (DMM), which predicted that the optimum hot working regime of Inconel625 was the compression condition of 1200 °C with 0.1 s−1, and predicted the instability zones were found out under the compression condition of 1100 °C with 0.1 s−1, 1200 °C with 1 s−1, 950 °C with 10 s−1 and 1150 °C with 80 s−1. The microstructure under the compression condition were in good agreement with the predictions of the processing map, under the optimum compression condition of 1200 °C with 0.1 s−1, the dynamically recrystallized grains were finer and the better mechanical properties, this condition should be selected to forging. In contrast, the grain sizes were uneven and the mechanical properties were poorer under the instability compression condition of 1100 °C with 0.1 s−1, 1200 °C with 1 s−1, 950 °C with 10 s−1 and 1150 °C with 80 s−1. Therefore, these instability zones should be avoided during hot forging.