부산대학교 도서관

The thermal fatigue behavior of superalloy Inconel 713LC was investigated at peak temperatures of 900, 1 000 and 1 100 °C. Thermal fatigue tests were performed on self-constraint single-edge V-type notch specimens. The effect of the maximum temperature, Tmax in the thermal cycles on the crack characteristics was studied. Under identical test conditions a comparable crack propagation rate was observed for all three peak temperatures. The results showed that cycle numbers for crack initiation decreased while crack propagation rate increased with the increase in peak temperature. Therefore, it was concluded that in the current experimental conditions, thermal fatigue resistance reduced dramatically with the rise of upper temperature. Through optical microscopy and scanning electron microscopy observation, it was found that the primary cracks generally propagated along a preferential direction. Microstructure changes after thermal fatigue are also discussed on the basis of scanning electron microscopy observation.