Influence of grain size and grain boundary misorientation on the fatigue crack initiation mechanisms of textured AZ31 Mg alloy

The deformation and crack initiation mechanisms were analyzed in a textured AZ31B-O Mg alloy subjected to fully-reversed, strain-controlled cyclic along the rolling direction after 50 cycles (approximately 33% of fatigue life). Distinct bands corresponding pyramidal slip or tensile twins found 538 grains out 2100 grains. Slip trace analysis showed that 72.3% 18.4% twin boundaries. Both twinning was only 9.1% with bands. Cracking widespread cycles. Grain boundary cracks ≈15% small (< 20 µm) they mainly associated high angle grain boundaries (>40º). also occur by transgranular parallel large (>45 µm). majority (>60%) these presented