低碳微合金双相钢拉伸断裂过程的动态观察

本文采用配备有拉伸装置的扫描电镜上连续地跟踪观察铁素体-马氏体双相组织在拉伸过程中微观断裂过程,并分析讨论了微裂纹的萌核与扩展条件及微观组织因素的影响。结果表明:双相钢的微观断裂机制是轴向应力和塑性座变的交互作用的结果。双相热处理工艺通过马氏体含碳量与体积率改变铁素体相的强度和变形行为以影响断裂机制。回火则由于碳化物在两相界面处析出与松驰应力集中而抑制显微裂纹的萌核与扩展。

Effect of Second Phase Morphology and Fraction on the Tensile Fracture Behaviour of Dual Phase steels

The dynamic microprocesses of tensile fracture behaviour of ferrite-martensite dual phase steels were observed with the in situ technique in SEMepuipped with a tensile platform.The experimental results demonstrate that theinteraction between axial stress and plastic strain is the microfracture mechanismof dual phase steel.Because of carbide precipitation on the interfaces and therelaxation of stress concentraction during the tempering process,the crackinitiation and propagation are significantly depressed.Different conditions of Crack initiation and propagation as well as thestructurally affecting factors have been discussed.Several dislocation modelshave been proposed to explain the corresponding fracture characteristics.