单调荷载下Q345钢焊缝金属的延性断裂性能研究

为了研究Q345钢焊缝金属的延性断裂性能，对9个试件进行了单调荷载下试验研究，试件设计考虑了不同应力三轴度和洛德角分布范围。分别采用Swift、Voce及Swift-Voce混合强化模型，拟合得到了能预测到断裂时的完整应力-应变曲线，其中Swift-Voce混合强化模型模拟各试件荷载-位移曲线精度最好。采用VGM，改进SWDM和Lou模型3种断裂模型，通过编写UVARM子程序，校准了各模型的材料参数，并对各试件进行了有限元断裂模拟预测，比较分析了各个模型的预测精度。结果表明，VGM模型对接近于平面应变状态的矩形缺口和槽板试件的预测结果误差较大，而改进SWDM和Lou模型通过引入洛德角参数来描述偏应力状态，对不同应力状态的试件断裂预测结果精度更高，模型的适用性更好。

DUCTILE FRACTURE BEHAVIOR OF WELD METAL FOR Q345 STEEL UNDER MONOTONIC LOADING

To study the ductile fracture behavior of weld metal for Q345 steel,nine specimens with different distribution of stress triaxiality and Lode angle were tested under monotonic loading.Swift,Voce and mixed swift-voce hardening models were used to fit the full stress-strain curves up to fracture.in comparison,the mixed Swift-Voce hardening model showed the best accuracy in simulating the load-displacement curves of the specimens.In addition,three kinds of fracture prediction models,namely,VGM,modified SWDM and Lou models,were utilized.The material parameters were calibrated by the UVARM subroutine and applied to the finite element numerical simulations.The accuracy of these prediction models were compared and analyzed.The results showed that the VGM model presented a relatively large error in predicting the fracture of rectangular notches and grooved plate specimens when they were near the plane strain state.However,the modified SWDM and Lou models produced accurate predictions when the Lode angle were considered to describe the deviatoric stress state.Based on the fracture prediction results,the modified SWDM and Lou models were effective for specimens of various stress states.