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为研究多轴应力下铁素体球铁延性断裂机制,采用三种不同曲率半径(ρ=2,4,10mm)的缺口圆柱试样进行拉伸试验,并用大弹塑性变形有限元分析法计算试样缺口部位的应力、应变分布。在中断拉伸试样上进行金相观察,跟踪石墨球与基体界面处微空洞的形核和长大。研究结果表明,当石墨球与基体界面处的应力到达650MPa时,微空洞形核,空洞长大和聚合导致延性断裂。
In order to study the mechanism of ductile fracture of ferrite ductile iron under multiaxial stress, three kinds of notched cylindrical specimens with different radius of curvature (ρ = 2, 4 and 10 mm) were used for tensile test and were calculated by using the elasto-plastic deformation finite element analysis Stress and strain distribution at the notch of specimen. Metallographic observation was performed on the interrupting tensile specimen to trace the nucleation and growth of the microvoids at the interface between the graphite ball and the substrate. The results show that when the stress at the interface between graphite ball and matrix reaches 650MPa, nucleation, voids growth and polymerization of microcavities lead to ductile fracture.