Quantitative analysis of the deformation modes and cracking modes during low-cycle fatigue of a rolled AZ31B magnesium alloy: The influence of texture

The anisotropy of mechanical behavior, as extensively reported in wrought Mg alloys, is ultimately associated with the variation of deformation modes. The influences of texture on the slip/twinning-detwinning activity, cracking modes and mechanical behaviors of a hot-rolled AZ31B alloy during strain-controlled low-cycle fatigue were investigated quantitatively and statistically by quasi-in-situ electron back-scattered diffraction (EBSD) analysis and scanning electron microscopy (SEM) observations coupled with slip trace analysis. The fundamental difference in the cracking modes and fatigue behaviors between the 0 degrees, 45 degrees, and 90 degrees samples (i.e., under loading directions of the normal direction (ND), 45 degrees, and rolling direction (RD)) is ascribed to the distinct activation sequences of deformation modes. The cyclic deformation-mode transitions throughout the whole fatigue life can be summarized as: (I) the 0 degrees sample: basal slip + tension twinning -> detwinning + basal slip; (II) the 45 degrees sample: basal slip -> basal slip; (III) the 90 degrees sample: tension twinning -> detwinning + basal slip. The underlying mechanism for the texture-dependency of deformation modes is discussed. Cracking modes are also closely related to the texture. Intergranular cracking was the primary cracking mode for the 0 degrees and 45 degrees samples, while tension twinning (TTW) cracking was the major cracking mode in the 90 degrees sample. The factors governing the site where microcracks were nucleated are analyzed.

Automated summary

In this study, the influences of texture on the fatigue behavior and cracking modes of magnesium alloy were investigated. The results show that the deformation modes and cracking modes are closely related to the texture. The cyclic deformation-mode transitions and the factors governing microcrack nucleation were analyzed.