In this study, a new fatigue testing method under shear and axial loading was developed for small specimens (3mm long and 0.3mm thick). The method was applied to a single crystal of pure iron and extra-low carbon steel in order to investigate the effect of shear and normal stress on cyclic slip activity. The specimen was sufficiently small to be prepared from a single crystal, aiming at a specific slip system in the shear loading direction. Moreover, the specimen had a single edge notch, which was designed to generate both pure shear stress and normal stress. Using this testing method, shear fatigue strength with a static normal stress on the slip system  was evaluated, and the fatigue strength was compared with that of polycrystalline ferrite steel with static axial loading.
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