中碳贝氏体钢拉伸变形中裂纹形成及扩展机制分析

残余奥氏体对中碳贝氏体钢的塑韧性起到非常重要的作用,采用贝氏体等温淬火工艺对残余奥氏体在拉伸变形作用下与裂纹形成及扩展的相互作用进行了研究.利用扫描电子显微镜(SEM)、透射电镜(TEM)和电子背散射衍射(EBSD)等对试验用钢基体及拉伸后颈缩区进行表征和分析.结果表明,拉伸过程中残余奥氏体细化明显,拉伸断裂后进行组织...

Analysis of crack formation and extension mechanism in tensile deformation of medium carbon bainitic steel

Retained austenite plays an important role in the plasticity and toughness of medium carbon bainitic steel. The interaction between retained austenite and crack formation and propagation under tensile deformation was studied by bainitic isothermal quenching process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) were used to characterize and analyze the test steel matrix and the necking area after tensile test. The results show that the retained austenite is refined obviously during the tensile process. After the tensile fracture, the microstructure observation shows that the dislocation network is formed by the dislocation tangled in the bainite lath bundle. The dislocation density increases, and the microstructure in the necking zone is obviously deformed. The retained austenite film is elongated and ruptured. The increase of the strain plasticity leads to the increase of the nucleation particles in the micropore, and the TRIP effect of the thin film retained austenite hinders its progress in the crack propagation process.