Two-component DF2016 criterion to characterize the fracture behavior of magnesium rare-earth alloys

Stress state has a significant influence on the fracture behavior of materials, especially for the lightweight-high strength metals. The research is carried out to uncover and characterize the stress state-dependent fracture behavior of two Mg alloys containing rare-earth (RE) elements. A two-component DF2016 fracture criterion is constructed by coupling two DF2016 models with the form of addition. The mechanical experiments in wide stress triaxiality were performed for WE43 and Mg-Gd-Y alloys, and the loading process was recorded by adopting digital image correlation technology. Based on the experiment-inverse engineering method, the deformation behavior of each specimen is captured by the numerical simulation with high accuracy. The fracture-related variables in the key element are extracted to present the strong dependence of fracture strain on the stress triaxiality and Lode parameter. Experimental results are used to calibrate the fracture parameters of the two-component DF2016, two-component DF2014 and DF2016 fracture criteria, respectively. The comparative result intuitively shows that the prediction performance of the two-component DF2016 criterion is prior to the other two models. This implies that the established fracture model is more suitable to characterize the fracture behavior of the two Mg-RE alloys. The research provides a comprehensive experimental database and numerical model for the fracture behavior of Mg-RE alloys under a pretty broad range of loading conditions, and is helpful in the engineering application.