Effect of tensile pre-strain on low-cycle fatigue behaviour of 7050-T6 aluminium alloy

Abstract The present study addresses the effect of tensile pre-strain histories on cyclic plastic deformation behaviour of 7050-T6 aluminium alloy. Low-cycle fatigue tests are conducted under fully-reversed conditions, with 8% tensile pre-strain, 4% tensile pre-strain, and 0% tensile pre-strain, at different strain amplitudes. After fatigue testing, fracture surfaces are examined by scanning electron microscopy and transmission electron microscopy to identify the main failure micro-mechanisms associated with the levels of pre-strain and strain amplitude. Microstructure is analysed by X-ray diffraction, transmission electron microscopy, and optical microscopy. The main findings suggest that tensile pre-strain histories are conducive to a reduction in fatigue life. This reduction increases with higher strain amplitudes.