Microstructural Evolution of a Pearlitic Steel Subjected to Thermomechanical Processing

The microstructural alterations suffered during the process of drawing deformation and subsequent annealing of pearlitic steel wires, were evaluated by scanning electron microscopy and atomic force microscopy. The deformed material showed the curling structure in cross section while, in the longitudinal section, the lamellae was aligned with the drawing direction. The microstructural characterization of deformed samples also allowed observing an interlamellar spacing reduction and the intermediate lamellae alignment process. After the heat treatment at 1000ºC for 5 min the microstructure was restored, however, few recrystallized grains were observed. The recovery was the dominant phenomenon, due to factors associated with curling structure that inhibited recrystallization.

本研究通过扫描电子显微镜（scanning electron microscopy, SEM）与原子力显微镜（atomic force microscopy, AFM），对珠光体钢丝在拉拔变形及后续退火过程中发生的微观组织演变进行了表征分析。经变形的试样在横截面中呈现卷曲状结构，而纵截面上的层片（lamellae）与拉拔方向保持对齐。对变形试样的微观组织表征还观测到层片间距减小以及中间层片的定向排列过程。经1000℃保温5 min的热处理后，试样的微观组织得以恢复，但仅观察到少量再结晶晶粒。由于与卷曲结构相关的因素抑制了再结晶过程，回复（recovery）成为该过程中的主导现象。