Evaluation of Thermal Aging Embrittlement in Directionally Solidified Ni-Base Superalloy by Small Punch Test

Abstract

In order to develop a procedure for evaluating the degradation of impact toughness in directionally solidified Ni-base superalloy CM247LC, which is commonly used for advanced gas turbine blades, the change in small punch (SP) fracture energy due to thermal aging has been investigated. The SP testing technique has been applied to materials aged under various aging conditions, and correlation with the results of Charpy V-notch impact tests has been examined. The experimental results reveal that SP fracture energy at room temperature decreases with aging at 800 °C and is uniquely correlated with high-temperature Charpy impact toughness. The current experiment has shown that the SP testing technique is useful in evaluating the degree of thermal aging embrittlement, one of the parameters required for remaining-life prediction of aged components.