The anisotropic fracture behavior of cold-drawn pearlitic steels was analyzed up to a true strain of 1.6. The structures were analyzed and quantified by scanning electron microscopy, electron backscatter diffraction and high-resolution electron microscopy. The aspect ratio Λ was defined to describe the fracture mechanism based on statistics pertaining to major axis and minor axis of pearlitic colonies, and the fitting formula was established as follows: $\Lambda =0.4\exp \left(2x\right)+0.65$. At Λ ≤ 2.75, the fracture mechanism shifts from cleavage to quasi-cleavage fracture due to dislocation generation, as the measured parameters of interlamellar spacing (ILS) showed no obvious decrease. At values of Λ > 2.75, ductile fracture mechanism becomes dominant due to a drastic decrease in ILS. The <110> ferrite fiber microtexture formed during the cold drawing process and the component exhibiting a gradient distribution from the surface to the central regions increased gradually with drawing. The crack propagation path was then deflected and formed a ‘V’ shape at ε ≤ 1.5. However, as carbon migrated from cementite to the ferrite near the interphase, the fracture path deflected again. Furthermore, two reasonable models were formulated to explain fracture crack forming and anisotropic fracture behavior. In addition, this study illustrated that the relative crystallographic orientation of the ferrite and cementite components followed the Bagarytski relationship. With increasing strain, the cementite layers transformed from single crystals into nanostructured polycrystals and even evolved an amorphous structure at the interface at strains above 1.5.

对冷拔珠光体钢的各向异性断裂行为进行了分析，直到真实应变为1.6。通过扫描电子显微镜，电子反向散射衍射和高分辨率电子显微镜对结构进行分析和定量。根据有关珠光体菌落长轴和短轴的统计数据，定义纵横比Λ来描述断裂机理，并建立拟合公式如下：$\Lambda =0.4\mathrm{经验值}（\mathrm{2个}X）+0.65$。在Λ≤2.75时 ，由于位错的产生，断裂机理从解理断裂转变为准解理断裂，因为层间间距（ILS）的测量参数没有明显降低。在Λ>  2.75的值时，由于ILS的急剧下降，延性断裂机制变得占主导地位。在冷拔过程中形成的<110>铁氧体纤维微织构和从表面到中心区域表现出梯度分布的组分随拉伸而逐渐增加。然后将裂纹扩展路径偏转，并在ε≤1.5时 形成“ V”形。但是，当碳在界面附近从渗碳体迁移到铁素体时，断裂路径再次偏转。此外，建立了两个合理的模型来解释断裂裂纹的形成和各向异性断裂行为。此外，这项研究表明，铁素体和渗碳体组分的相对晶体学取向遵循巴加里茨基关系。随着应变的增加，渗碳体层从单晶转变为纳米结构的多晶，甚至在应变高于1.5时在界面处形成无定形结构。