Relationship between the fatigue behavior and grain structures of an as-extruded Mg-6.2%Zn-0.6%Zr (in wt.%) alloy

Through investigating the tension-tension fatigue behavior of an as-extruded Mg-6.2 wt.%Zn-0.6 wt.%Zr (ZK60) alloy, it revealed that the determined fatigue strength at 10 7 cycles was quite sensitive to the grain structure. Among them, the fine grain structure had the highest fatigue strength of 130 MPa, whereas the typical "bi-modal" grain structure had the lowest fatigue strength of 110 MPa. Failure analysis demonstrated that for the fine grain structure, fatigue cracks preferentially nucleated at grain boundaries. For the "bi-modal" and coarse grain structures, the fatigue crack initiation was dominated by the cracking along slip bands. (C) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.