Temperature dependence of critical resolved shear stress using without making large single crystalline specimens

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02462
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: Kyushu University
• Principal Investigator: Tanaka Masaki 九州大学, 工学研究院, 教授 (40452809)
• Co-Investigator(Kenkyū-buntansha): 森川 龍哉 九州大学, 工学研究院, 助教 (00274506) ; 奥山 彫夢 木更津工業高等専門学校, 電子制御工学科, 助教 (50804655)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 転位 / すべり変形

Outline of Final Research Achievements

In this study, the temperature dependence of critical resolved shear stress (CRSS) for each slip system in Ti-6Al-4V was clarified relatively by measuring the slip bands after plastic deformation. The results show that, at the strain rates used in this study, not only the prismatic plane, which is conventionally known, but also the basal plane is active at temperatures below 225 K. The prismatic slip is also active high at temperatures below 225 K. The results of the inverse analysis using the finite element method showed that the slip deformation in single crystals is localised so that the plastic deformation starts at higher indentation loads in bending than those expected from CRSS.

Free Research Field

結晶塑性学

Academic Significance and Societal Importance of the Research Achievements

チタン合金のように結晶の対称性が低い材料では，結晶粒毎の塑性変形挙動が異なることから延性が低く，加工性に劣る．構造用チタン合金として最も良く用いられているTi-6Al-4Vでは，塑性変形挙動の異なるα相とβ相が混在して塑性変形が起こる．またチタン合金は延性に乏しく，部材の加工に制限が生じるため，製品形状の自由度が少ない．本研究の成果は，チタン合金における塑性変形挙動の素過程を明らかにするものであり，延性に富むチタン合金の設計指針を与えるものに繋がる．