Micromechanical characterization of hydrogen embrittlement related to martensitic transformation

2015 Fiscal Year Final Research Report

• Project/Area Number: 25420758
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural/Functional materials
• Research Institution: Kumamoto University
• Principal Investigator: Mine Yoji 熊本大学, 自然科学研究科, 准教授 (90372755)
• Co-Investigator(Kenkyū-buntansha): TAKASHIMA KAZUKI 熊本大学, 大学院自然科学研究科, 教授 (60163193)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 水素脆化 / 変形誘起マルテンサイト変態 / ステンレス鋼 / マイクロ材料試験

Outline of Final Research Achievements

Micro-bending and micro-tensile testing was employed to clarify the effect of microstructure developed by deformation with hydrogen on hydrogen embrittlement of metastable austenitic steel. Micro-bending testing of microstructures developed at the crack tip revealed that cracking readily occurred in the specimen deformed with hydrogen. Micro-tensile testing of samples processed by high-pressure torsion revealed the effect of intermediate phase for martensitic transformation on plasticity. Deformation-twinning in the uncharged steel acts as an intermediate phase in the transformation to alpha prime martensite, which contributes to a good balance between strength and ductility. Hydrogen charging in the steel facilitates the formation of epsilon martensite as an intermediate phase in the transformation, thereby leading to the strain localization. However, dynamic alpha prime martensitic transformation in the presence of hydrogen is requisite for severe HE with quasi-cleavage.

Free Research Field

材料工学・構造材料