A new testing method for investigating the shear-mode fatigue crack growth behavior in hydrogen environment

12th International Conference on Damage Assessment of Structures

Akaki, Y.^1 ; Matsuo, T.^2,3 ; Nishimura, Y.^4 ; Miyakawa, S.^4 ; Endo, M.^2,3

Graduate School of Engineering, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka

814-0180, Japan^1

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

814-0180, Japan^2

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

814-0180, Japan^3

Materials Engineering RandD Division, DENSO CORPORATION, 1-1 Syowa-cho, Aichi, Kariya

448-8661, Japan^4

关键词: Crack growth behavior;    Cyclic shear stress;    Experimental methods;    Fatigue crack growth behavior;    Fundamental principles;    Hydrogen precharging;    Threshold behavior;    Transportation equipments;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/842/1/012065/pdf
DOI  :  10.1088/1742-6596/842/1/012065

来源: IOP

【 摘 要 】

Ball bearing is widely used in a variety of machines including the transportation equipments of the automobiles and airplanes. Flaking failure is a common problem for ball bearing and it is caused by shear-mode fatigue crack growth under cyclic shear stress. Further, it is known that the premature flaking is attributed to the combined effect of hydrogen penetration into the material and cyclic shear stress during the operation. Therefore, in order to ensure the integrity of ball bearing, it is necessary to clarify the effect of hydrogen on shear-mode fatigue crack growth behavior, in particular, the threshold behavior. The evaluation of the shear-mode crack growth behavior is not easy because mode I crack branching occurs easily. Our previous studies revealed that it is required to apply static compression in the direction of specimen axis to attain a stable shear-mode fatigue crack growth. In addition, successive hydrogen supply to the specimen is essential for the evaluation of hydrogen effect on the fatigue threshold because hydrogen emits from the specimen during the fatigue test. In other words, the hydrogen-precharging method, commonly used for the research on hydrogen embrittlement, is not appropriate for the evaluation of fatigue threshold. In this study, to solve these problems, we have developed a novel, easy-to-use experimental method to evaluate the threshold behavior of shear-mode fatigue crack in the presence of hydrogen. The fundamental principle of the method is introduced in this paper.