Fatigue of aluminum as affected by temperature and intermittent periods of rest

Abstract

This investigation was undertaken in an attempt to determine the behavior of high purity aluminum when subjected to fatigue stressing in rotary bending at various elevated temperatures, and also to study the effects on fatigue life when the material was given intermittent periods of rest. Two types of rest periods were given; 1) room temperature resting from fatigue cycling at elevated temperature, and 2) resting at higher temperature after stressing at ambient temperature. Because of the limited time available and the desire to apply statistical methods of analysis, testing was restricted to only a single stress level for each phase of the experiment. Up to the highest temperature tested (600[degrees]F), results for continuous stress cycling indicate a gradual reduction in fatigue life with temperature. Rest periods at room temperature contributed only negligible changes in fatigue life, but all tests with rest periods at elevated temperature disclosed a sizable increase. The increase in fatigue life was a maximum when resting was carried out at temperatures in the neighborhood of the recrystallization temperature. In addition, it is curious to note, that in the continuous cycling tests, scatter of results was a sharp minimum at recrystallization temperature.