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通过光滑试件及不同曲率半径缺口圆柱试件的拉伸试验,实现对镁合金MB2的单向及多向应力状态加载。结合数值模拟分析,研究了不同试件在拉伸加载过程中应力状态的变化。以应力三轴度为参数,给出了镁合金MB2等效破坏应变的变化规律,在应力三轴度-等效破坏应变空间建立了镁合金MB2的失效破坏准则。利用扫描电镜对试件断口形貌进行观察,分析了导致材料宏观延性变化的微观损伤机理,对不同应力状态下镁合金MB2的失效破坏行为做出了合理解释。
The uniaxial and multi-directional stress loading of magnesium alloy MB2 was achieved by the tensile test of the smooth specimen and the notch specimens with different radius of curvature. Combined with numerical simulation analysis, the stress state of different specimens during tensile loading was studied. Taking the stress triaxiality as parameter, the variation law of equivalent failure strain of magnesium alloy MB2 is given, and the failure failure criterion of magnesium alloy MB2 is established in the stress triaxiality-equivalent failure strain space. The fracture morphology of the specimen was observed by scanning electron microscopy. The microscopic damage mechanism leading to macroscopic ductility change of the material was analyzed. The failure failure behavior of magnesium alloy MB2 under different stress states was reasonably explained.