利用TEM, SEM和纳米压痕仪研究了珠光体钢丝在冷拉拔形变过程中, 珠光体层片取向对其形变及力学性能的影响. 结果表明: 与拉拔轴向夹角较小的珠光体层片, 通过珠光体团旋转, 使珠光体层片转向平行于拉拔轴向, 并率先形成铁素体<110>丝织构; 铁素体中位错由单滑移到多滑移, 最终变成同一滑移系的单滑移, 位错分布较均匀, 渗碳体与铁素体保持协调变形. 与拉拔轴向夹角较大的珠光体层片, 通过弯折转向接近平行拉拔轴向, 渗碳体发生断裂碎化、铁素体中形成位错胞, 造成后续形变困难, 层片缓慢减薄. 经拉拔形变后, 平直珠光体的显微硬度高于弯折珠光体, 表明接近平行于拉拔轴向的珠光体层片加工硬化率较高, 有利于形变强化.

Cold drawing pearlitic steel wires with ultra-high strength have important applications such as the automobile tire, springs rope and bridge cables. There have been many investigations which are paid attention to the hardening mechanisms of pearlitic steel wire, covering evolution of microstructure, texture and dislocation. In this work, effects of pearlitic lamella orientation on mechanical properties and deformation of pearlite steel wire in cold drawing were investigated by combining TEM, SEM and nano-indentor. The experimental results showed that pearlitic lamellae having low angle with drawing direction would be turned to parallel the drawing direction through a combined rotating process of pearlite colonies. The <110> fiber texture in the ferrite phase formed and the distribution of dislocations in ferrite was almost uniform. The deformation between cementite and ferrite was coordinated. Pearlitic lamellae having large angle with drawing direction would be bent and turned to parallel the drawing direction. It was difficult for the bent pearlite to deform because of the fragmentation of cementite and formation of dislocation cell in ferrite. After cold drawing process, the micro-hardness of straight pearlite was higher than that of bent pearlite. The result indicated that pearlitic lamellae having low angle with drawing direction have higher working-hardening rate in drawing.