Quantitative characterization of cleavage and hydrogen-assisted quasi-cleavage fracture surfaces with the use of confocal laser scanning microscopy

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• 作者：E. Merson^a ; ; A.V. Kudrya^b ; V.A. Trachenko^b ; D. Merson^a ; ^c ; V. Danilov^a ; A. Vinogradov^a ; ^d
• 关键词：Cleavage ; Quasi-cleavage ; Facets ; Hydrogen-assisted cracking ; Confocal laser scanning microscopy ; Fisheye
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：17 May 2016
• 年：2016
• 卷：665
• 期：Complete
• 页码：35-46
• 全文大小：5508 K

文摘

“True” cleavage (TC) and quasi-cleavage (QC) fracture surfaces of low-carbon steel specimens tested in liquid nitrogen and after hydrogen charging respectively were investigated by quantitative confocal laser scanning microscopy (CLSM) and conventional scanning electron microscopy (SEM) with electron-backscattered diffraction (EBSD). Topological and crystallographic features of the TC fracture surface are found in good agreement with the generally accepted cleavage mechanism: TC facets diameters correspond to those of grains; the crack path strictly follows the crystallographic orientation of grains and the most of the cleavage cracks are parallel to {100} planes. On the 2D SEM images, the QC facets appeared resembling the TC ones in terms of river line patterns, shapes and sizes. However, the substantial differences between the topography of these two kinds of fracture surfaces were revealed by 3D CLSM: the average misorientation angle between QC facets and the roughness of the QC fracture surface were much lower than those measured for TC. It is demonstrated that all these features are attributed to the specific fracture mechanism operating during hydrogen-assisted cracking.