Fatigue behavior of AZ31 magnesium alloy evaluated using single crystal micro cantilever specimen

• Fatigue test of Mg alloy using micro cantilever specimen.
• Crystallographic analyses by EBSD.
• Schmid factors calculation of activated slips and twins.
• Analyses of fatigue damage based on crystallographic orientations.
• Proposal of fatigue mechanism in single crystal Mg alloy.

Plane bending fatigue tests of magnesium alloy, AZ31, were conducted using micro cantilever specimens, which were composed of single crystals. The grain orientation of each specimen was analyzed by an electron back-scattered diffraction (EBSD) method. The slip and twin systems operated during fatigue tests were identified from the line analyses on the specimen surface. Depending on the crystallographic orientation, fatigue fracture modes were classified into three types, namely basal-slip, primary-twin and pyramidal-slip dominated fatigue. When the fatigue damage was dominated by pyramidal slip operation, the fatigue strengths were the highest. The lowest fatigue strengths were obtained in the basal-slip-dominated fatigue mode.