Clarification of the effects of trace elements on hydrogen embritllement and establishment of technique to evaluate the structural integrity

2015 Fiscal Year Final Research Report

• Project/Area Number: 25420006
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Materials/Mechanics of materials
• Research Institution: Ibaraki University
• Principal Investigator: Konosu Shinji 茨城大学, 工学部, 名誉教授 (90091686)
• Co-Investigator(Kenkyū-buntansha): HORIBE TADASHI 茨城大学, 工学部, 教授 (50141867) ; MORI KOTARO 茨城大学, 工学部, 助授 (40712740)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 水素脆化 / 破壊力学

Outline of Final Research Achievements

By focusing attention on the effects of trace elements on hydrogen embrittlement sensitivity for iron-based materials, the thermal desorption analysis and electro probe microanalysis were conducted. A number of dispersed vanadium carbides caused by the addition of roughly 0.3 wt.% vanadium is effective in mitigating hydrogen embrittlement, while the reduction of impurity elements such as phosphorus and tin has little impact on threshold for hydrogen-induced fracture. For a structural integrity assessment, the mechanical characteristics such as threshold stress intensity factors at the onset of hydrogen-assisted crack growth, KIH, the tearing resistance, dJ/da and subcritical crack growth rates at constant loads, da/dt need to be known. In this study, the newly developed offset potential-drop method was employed to clarify these properties for 2.25Cr-1Mo steels with trace element controls.

Free Research Field

材料強度学