Study of Low Cycle Thermal Fatigue and Aluminum Alloy Microstructure

Abstract

The most popular aluminum alloy, AC2B-T6, was tested for thermal fatigue with the center of strain amplitude offset to take realistic engine running conditions into consideration. Test specimens were overaged to study the effects of tempering temperature on life, which turned out to be very effective for lengthening life. In the TEM microstructure observation, attention was focused on precipitates, and the average size and number of precipitates were measured. The effects of temperature, loading period strain amplitude on the characteristics of precipitates were studied to establish relation with fatigue life. As a result, it was found that the average size of a certain type of precipitates has a strong correlation with fatigue life, and was concluded that not only material properties but also microstructure should be studied to develop an aluminum alloy.