Hydrogen-assisted fracture features of a high strength ferrite-pearlite steel
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2019年第6期
论文作者：Yuefeng Jiang Bo Zhang Dongying Wang Yu Zhou Jianqiu Wang En-Hou Han Wei Ke
文章页码：1081 - 1087
摘 要：Up to now, the exact reason of hydrogen-induced fracture for ferrite-pearlite（FP） steel is still not fully understood. This study presents detail observations of the feature beneath the fracture surface with the aim to reveal the hydrogen-induced cracking initiation and propagation processes. Slow strain rate tensile（SSRT） testing shows that the FP steel is sensitive to hydrogen embrittlement（HE）. Focused ion beam（FIB）was used to prepare samples for TEM observations after HE fracture. The corresponding fractographic morphologies of hydrogen charged specimen exhibit intergranular（IG） and quasi-cleavage（QC） fracture feature. Pearlite colony, ferrite/pearlite（F/P） boundary and the adjacent ferrite matrix are found to be responsible for the initial HE fracture and the subsequent propagation. With increasing of the stress intensity factor, fracture mode is found to change from mixed IG and QC to entire QC feature which only occurs at the ferrite matrix. No crack is observed at the ferrite/cementite（F/C） interface. This may be mainly due to the limited pearlite lamella size and relatively low interface energy.
Yuefeng Jiang，Bo Zhang，Dongying Wang，Yu Zhou，Jianqiu Wang，En-Hou Han，Wei Ke
摘 要：Up to now, the exact reason of hydrogen-induced fracture for ferrite-pearlite（FP） steel is still not fully understood. This study presents detail observations of the feature beneath the fracture surface with the aim to reveal the hydrogen-induced cracking initiation and propagation processes. Slow strain rate tensile（SSRT） testing shows that the FP steel is sensitive to hydrogen embrittlement（HE）. Focused ion beam（FIB）was used to prepare samples for TEM observations after HE fracture. The corresponding fractographic morphologies of hydrogen charged specimen exhibit intergranular（IG） and quasi-cleavage（QC） fracture feature. Pearlite colony, ferrite/pearlite（F/P） boundary and the adjacent ferrite matrix are found to be responsible for the initial HE fracture and the subsequent propagation. With increasing of the stress intensity factor, fracture mode is found to change from mixed IG and QC to entire QC feature which only occurs at the ferrite matrix. No crack is observed at the ferrite/cementite（F/C） interface. This may be mainly due to the limited pearlite lamella size and relatively low interface energy.
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