Effect of Thermomechanical Deformation Temperature and Strain Rate on Annealing Response and Microstructure of a Ni-Based Superalloy
摘要
Nickel-based superalloys, particularly Inconel-718, are critical materials for gas turbine, energy and aerospace applications owing to their advanced mechanical behavior at higher temperatures, excellent corrosion resistance, and thermal stability. The mechanical behavior of Inconel-718 superalloys highly relies on their microstructure and precipitates, which can be controlled by thermomechanical and heat treatments. This study analyzes the correlation between microhardness and microstructures developed through a thermomechanical and heat-treatment process of Inconel-718. Thermomechanical deformations and heat treatments were executed to develop different microstructures. The EBSD technique is performed to analyze the characterization of microstructures. An extensive range of microstructures having microhardness values from 210 to 416 HV was measured after hot deformation and annealing process. In this study, the annealing temperatures of 900 °C, 1000 °C, and 1100 °C and strain rates 0.001 s−1, 0.1 s−1, and 10 s−1 were correlated with microstructures and microhardness. The microhardness value at strain rates 0.001 and 0.1 s−1, increases from 900 to 1000 °C, and then, it decreases at 1100 °C. A clear trend between hot deformed temperature, strain rate, and microhardness was established.