The Effects of Specimen Grain Size and Environment on the Fatigue Life of Ofhc Copper

摘要

The note presents the results of a study of the effects of grain size and environment on the fatigue life of OFHC copper specimens. Tests conducted in alternating torsion on specimens of two different grain size groups showed that an increase in specimen grain size results in a decrease in fatigue life at both high and low strain amplitudes. Similar tests under low and high humidity showed that humidity has a negligible effect on fatigue life for either high or low strain amplitude and for large or small grain size. The effects of elevated temperatures were found to be more complex. At high strain amplitudes the fatigue life decreased continuously as the temperature was increased. At low amplitudes the life dropped as the temperature was raised to 200C., but then remained approximately constant when the temperature was raised further to 350C. An examination of the microstructural changes caused by the fatigue tests revealed damage characteristics of Wood's H range for the tests at high amplitudes and room temperature, with slight variations for the tests at high temperature. Damage characteristics of Wood's S range were found for low amplitude tests at room temperature, with significant grain growth occurring at high temperature. (Author)