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arXiv · 2109.08404

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

Abbas Jamali·Anxin Ma·Javier LLorca
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Abstract

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

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Abbas Jamali, Anxin Ma, Javier LLorca. 2021-09-17. Influence of grain size and grain boundary misorientation on the fatigue crack initiation mechanisms of textured AZ31 Mg alloy. https://arxiv.org/abs/2109.08404

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