Abstract The deformation mechanisms and fracture of nano-structured pearlitic steels with inter-lamellar spacing between 60 and 160 nm have been studied in-situ using a tensile stage inside a scanning electron microscope. Fragmentation of cementite lamellae for finer pearlite was observed post ultimate tensile strength (UTS) in regions where the lamellae were aligned along the tensile axis. For coarse pearlite, cementite fragmentation initiated prior to UTS which became more severe post UTS. For coarse pearlite, the fragmented regions were distributed randomly and fragmentation was also observed for lamellae inclined to the tensile axis, thus suggesting a shear cracking dominated fracture. With refinement of lamellae spacing, fragmentation of cementite lamellae occurred simultaneously traversing the entire width of a pearlitic colony because of the strain energy release suggesting a dominating fiber stress transfer failure mechanism. For coarser pearlite, cracks in multiple colonies got connected after reaching the UTS.

中文翻译：

---

珠光体纳米结构改变变形机制的原位研究

摘要 使用扫描电子显微镜内的拉伸台原位研究了层间距在 60 到 160 nm 之间的纳米结构珠光体钢的变形机制和断裂。在薄片沿拉伸轴对齐的区域中，在极限拉伸强度 (UTS) 后观察到渗碳体薄片破碎以获得更细的珠光体。对于粗珠光体，渗碳体碎裂在 UTS 之前开始，在 UTS 之后变得更加严重。对于粗珠光体，破碎区域是随机分布的，并且对于倾斜于拉伸轴的薄片也观察到破碎，因此表明以剪切开裂为主的断裂。随着薄片间距的细化，由于应变能释放表明主要的纤维应力传递失效机制，渗碳体片层的碎裂同时发生在珠光体群的整个宽度上。对于较粗的珠光体，到达 UTS 后，多个群落中的裂纹连接起来。