Fatigue crack initiation of magnesium alloys under elastic stress amplitudes: A review

Abstract

The most advantageous property of magnesium (Mg) alloys is their density, which is lower compared with traditional metallic materials. Mg alloys, considered the lightest metallic structural material among others, have great potential for applications as secondary load components in the transportation and aerospace industries. The fatigue evaluation of Mg alloys under elastic stress amplitudes is very important in ensuring their service safety and reliability. Given their hexagonal close packed structure, the fatigue crack initiation of Mg and its alloys is closely related to the deformation mechanisms of twinning and basal slips. However, for Mg alloys with shrinkage porosities and inclusions, fatigue cracks will preferentially initiate at these defects, remarkably reducing the fatigue lifetime. In this paper, some fundamental aspects about the fatigue crack initiation mechanisms of Mg alloys are reviewed, including the 3 followings: 1) Fatigue crack initiation of as-cast Mg alloys, 2) influence of microstructure on fatigue crack initiation of wrought Mg alloys, and 3) the effect of heat treatment on fatigue initiation mechanisms. Moreover, some unresolved issues and future target on the fatigue crack initiation mechanism of Mg alloys are also described.

Key words： Mg alloys; fatigue behavior; microstructure; crack initiation; deformation mechanism

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant Nos. 51701129, 51271183 and 51301172), Initiation Foundation of Shenyang Ligong University for Doctoral Research, the National Basic Research Program of China (973 Program) (Grant No. 2013CB632205), the National Key Research and Development Program of China (Grant No. 2016YFB0301105), and Innovation Fund of Institute of Metal Research, Chinese Academy of Sciences.

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