SS400钢焊接接头抗断性能的数值评估

SS400钢是一种超细晶粒、超纯净、具有优良综合力学性能的新一代钢铁材料，其焊接结构性能的研究对其推广应用具有重要的意义。文中通过数值分析方法，以SS400母材性能为参照，对其实际焊接接头的抗断裂性能进行评估。采用MARC商用软件，对不同中心贯穿裂纹尺寸的SS400母材及其实际焊接接头拉伸板模型进行三维有限元计算和拉伸过程模拟。焊接方法为脉冲熔化极混合气体保护焊，焊接板的中心裂纹处于焊缝与热影响区之间的熔合区。用作比较的母材板的裂纹尺寸和位置、网格划分、边界条件等与焊接板完全相同。根据计算结果，分析焊接接头力学不均匀性对应力应变场的影响，并依据全面屈服理论对断裂参量CTOD进行分析比较。结果表明，焊接接头的CTOD值均低于同裂纹尺寸的纯母材。因此，该焊接接头拉伸板的抗断性能应优于纯母材。

NUMERICAL EVALUATION OF FRACTURE PERFORMANCE FOR A SUPER STEEL SS400

Steel SS400 is a kind of new steel with superfine grain and super purity, and has an excellent mechanical property. Study of welding structure characteristics is essential for its promotion and application. The method of numerical analysis was used to evaluate the fracture properties of the actual weld joints in reference to SS400 parent material properties. With the help of a MSC. MARC commercial software, the fracture mechanics parameters of the parent material and the actual weld joint with various central transverse crack lengths were computed, and the tensile process of that model was simulated with the three-dimension finite element method. MIG was used in the welding process. The central crack was in the fusing zone between the weld and heat affection zone(HAZ). The crack size and position, the plotting of the mesh and the boundary condition of the parent material panel used for comparison were entirely the same as those of the welding panel. With the help of the results of the computation, the effect of the weld joint mechanical heterogeneity on stress-strain field was analyzed. Furthermore, based on the theory of full-scale yielding, the fracture parameter CTODs, was analyzed and compared. The result shows that the CTOD value of each weld joint is invariably lower than that of the pure parent material with the same crack size. Consequently, the fracture-resistant ability of the weld joint is superior to that of the all parent material.