Effects of Temperature of Low-Cycle Thermal Fatigue Life and Microstructure for Aluminum Alloy

Low-cycle thermal fatigue tests were carried out on aluminum alloys, AC2B-T6. As test temperature makes great effects on mechanical properties, more efforts were focused on the temperature range to find out relation between life and constraint factor of thermal strain. The investigation has turned out that the test specimens which were subjected to temperatures higher than the tempering temperature, and those which were not, greatly differ in mechanical properties Microstructures of test specimens for three temperature ranges were examined by TEM. Fracture surfaces were also observed by SEM. The observation of microstructure has revealed that the highest and lowest temperature ranges greatly differ in the shapes of precipitates and precipitate density, and that the difference make great effect on life. Fracture appearances were also clarified by the investigation. Lastly, test specimens were overaged to study the effects of tempering temperature on life, which turned out to be very effective for lengthening life.