Low cycle fatigue behavior of extruded AZ31B magnesium alloy
(1. Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education,Northeastern University, Shenyang 110819, China;2. School of Materials Science and Engineering, Shenyang Aerospace University, Shenyang 110136, China;3. LEM3, University of Metz, 57045 Metz, France)
Abstract: The strain-controlled fatigue behavior of an extruded AZ31B magnesium alloy was investigated under symmetric loading at different total strain amplitudes. It is found that except for the low strain magnitude of 0.5%, the alloy exhibits obviously cyclic strain-hardening characteristics during fatigue at strain magnitudes of 0.7%, 0.9%, 1.3% and 1.5%. At the strain of magnitude 0.5%, the alloy exhibits a cyclic hardening characteristic in the initial stage and then a stress constant remaining in the late stage. The hysteresis loop is symmetrical in shape at the strain magnitude of 0.5%, and becomes asymmetrical due to the twinning-detwinning process when the strain magnitude increases. The shape difference of the hysteresis loops between the low and high strain magnitudes was discussed in terms of the differential deformation mechanisms.
Key words: AZ31B magnesium alloy; twinning; dislocation slip; hysteresis loop; cyclic hardening