Fatigue crack propagation behavior and debris formation in Ti-6Al-4V alloys with different grain size

6th International Conference on Fracture Fatigue and Wear

Kim, H.J.^1,2 ; Nakahigashi, J.^3 ; Ebara, R.^2 ; Endo, M.^1,2

Department of Mechanical Engineering, Fukuoka University, 8-19-1, Nanakuma, Jonan-ku, Fukuoka

814-0180, Japan^1

Institute of Materials Science and Technology, Fukuoka University, 8-19-1, Nanakuma, Jonan-ku, Fukuoka

814-0180, Japan^2

Department of Mechanical System Engineering, Fukuyama University, 1-3, Gakuen, Fukuyama

729-0292, Japan^3

关键词: Fatigue characteristics;    Fatigue crack propagation behavior;    Fatigue properties;    High specific strength;    Metallic material;    Severe plastic deformations;    Small fatigue cracks;    Tensioncompressions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/843/1/012039/pdf
DOI  :  10.1088/1742-6596/843/1/012039

来源: IOP

【 摘 要 】

Titanium alloy is widely used in applications where high specific strength as well as good heat and corrosion resistance is required. Consequently, there are a number of studies on the fatigue characteristics of titanium alloys. In recent years, grain refinement for metallic materials processed by several methods, such as severe plastic deformation, has been studied to improve the mechanical properties. Grain refinement of titanium alloy by the protium treatment is a new technology, and the fatigue properties of this material have yet to be sufficiently studied. Therefore in this study, tension-compression fatigue tests were conducted for a protium treated Ti-6Al-4V alloy with ultra-fine grains of 0.5 μm in average size as well as for an untreated alloy with conventional grains of 6 μm. Specimens had shallow, sharp notches with the depth of 50 μm and the root radius of 10 μm, which enabled successive observation of the initiation and early propagation behaviors of small fatigue cracks. Substantial amount of oxide debris was formed along the crack during crack propagation. The role of debris was discussed in association with propagation resistance.