MICROMECHANICAL STRESSES DURING LOW CYCLE FATIGUE OF AN OVERAGED Al‐Mg‐Si ALLOY

Abstract The evolution of micromechanical stresses; flow stress, kinematic back stress and isotropic drag stress during room temperature, uniaxial, low cycle fatigue of overaged Al‐Mg‐Si alloy is studied. Continuous real‐time measurements of yield stresses are made in cyclic tension and compression, within the hysteresis loop, at different strain amplitudes, strain rates and number of cycles. An asymmetry is observed in flow stress and kinematic back stress in tension and compression half cycles during cyclic hardening and saturation. The phenomenological results have been analyzed in terms of kinematic and isotropic type microstructural mechanisms.