In-situ tensile-shear test in SEM and DIC analysis of two pearlitic steel microstructures: undeformed-coarse and deformed-refined
In-situ tensile-shear test in SEM and DIC analysis of two pearlitic steel microstructures: undeformed-coarse and deformed-refined
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DOI：
10.1016/j.jmrt.2023.05.154
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发表时间：
2023-05
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通讯作者：
P. B. Paiva Leão;João R. Barros Neto;S. Rodrigues;João Victor B. Xavier;J. L. Cardoso;Luís Flávio Gaspar Herculano;T. N. Lima;A. Ramirez;Hamilton Ferreira G. de Abreu
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作者：
P. B. Paiva Leão;João R. Barros Neto;S. Rodrigues;João Victor B. Xavier;J. L. Cardoso;Luís Flávio Gaspar Herculano;T. N. Lima;A. Ramirez;Hamilton Ferreira G. de Abreu
利用扫描电镜（SEM）原位拉伸剪切（TS）试验研究了未变形粗晶（UC）和变形细化（DR）珠光体钢的变形和断裂行为。设计了原始TS样品几何形状。二次电子（SE）图像实时记录和数字图像相关技术应用于他们。由于DR的精细的微观结构，SE图像，背散射电子图像，和电子背散射衍射技术，另外采用在DR条件下的中断TS测试。结果表明，在高温剪切过程中，DR珠光体组织比UC组织具有更高的剪切强度和能量吸收。UC的珠光体显微组织经历了高度的显微组织变形，而DR似乎是高度刚性的。应变集中主要出现在UC的菌落边界、DR的GBs-α和DR的菌落中，且板片平行于拉伸方向。UC和DR试样分别在菌落边界和铁素体/铁素体界面观察到脱粘现象。这些脱粘现象都与珠光体显微组织条件下的裂纹形核有关。最后，剪切破裂突然发生UC和DR缓慢，导致断裂主要包括剪切平面和韧窝，分别。
The deformation and fracture behaviors of undeformed-coarse (UC) and deformed-refined (DR) pearlitic steel microstructure were investigated via in-situ tensile-shear (TS) test in scanning electron microscopy (SEM). An original TS sample geometry was designed. Secondary Electron (SE) images were recorded in real-time and digital image correlation technique was applied to them. Due to the DR's refined microstructure, SE images, backscatter electron images, and electron backscatter diffraction techniques were additionally employed in the DR condition under an interrupted TS test. The results showed that the DR pearlitic microstructure presented a higher shear strength and absorbed energy, compared to UC, during the TS performance. UC's pearlitic microstructure experienced a high degree of microstructural deformation, while DR seemed to be highly rigid. Strain concentration was mainly observed in the UC's colony boundaries, in the DR's GBs-α, and in the DR's colony with lamellae parallel to the tensile direction. The decohesion phenomenon was observed at colony boundaries and ferrite/cementite interfaces, respectively, for UC and DR specimens. These decohesion phenomena were related to crack nucleation in both pearlitic microstructure conditions. Finally, the shear rupture occurred abruptly for UC and slowly for DR, resulting in fractures mainly comprised of a sheared flat surface and dimples, respectively.