Hot Deformation Behavior and Processing Map of Nimonic 105 Superalloy for 700 °C Advanced Ultra-supercritical Power Plants

The high-temperature deformation behavior of Nimonic 105 alloy was investigated through carrying out hot compression at temperatures of 1050-1200 degrees C and strain rates of 0.01-10 s(-1). The stress-strain data obtained during hot compression was utilized to establish constitutive equation and processing maps. The hot deformation activation energy of the alloy is calculated as 453.99 kJ/mol. On the basis of the processing map and microstructure analysis, the optimum hot working conditions of the alloy are determined to be at temperatures of 1070-1175 degrees C and strain rates of 0.05-0.35 s(-1). At true strain of 0.9, the processing map displays two unstable domains. The first one occurs at temperatures of 1130-1200 degrees C and strain rates of 0.6-10 s(-1), at which flow instability results from intergranular cracks. The second one is at temperatures of 1050-1100 degrees C and strain rates of 0.6-10 s(-1), and flow instability is caused by the formation of cavities and cracks at the original grain boundaries.