The high-cycle fatigue and fracture behavior of aluminum alloy 7055

This paper highlights the results of a study on the high-cycle fatigue, deformation and fracture behavior of aluminum alloy 7055. Specimens of the alloy, in the T7751 temper, were cyclically deformed over a range of stress amplitudes at both ambient and elevated temperatures. While an increase in test temperature was found to have a detrimental influence on cyclic fatigue life of the transverse orientation specimens, little influence was found on the longitudinally oriented specimens. The macroscopic fracture mode was essentially identical regardless of the orientation of the test specimen with respect to the wrought rolled plate. Cyclic fatigue fracture, on a microscopic scale, revealed features reminiscent of locally ductile and brittle mechanisms. The microscopic fracture behavior was a function of test temperature. The mechanisms governing cyclic fatigue life and fracture behavior are discussed in light of the mutually interactive influences of microstructural effects, matrix deformation characteristics and test temperature.