抄録
To investigate fatigue fracture behavior of small titanium single crystals, plain bending fatigue test method for thin sheet specimens was developed. One end of the sheet specimen was fixed at a voice coil of a loudspeaker and the other end was set free. A bending mode resonance occurs in the specimen due to forced vibration at the fixed end. In A-specimen whose surface plane and loading direction were (0001) and [1120], the fatigue crack propagated parallel to {1100} plane and striation-like markings were observed on the fatigue fracture surfaces. In B-specimen with (0001) surface and [1100] loading direction, the fatigue crack also propagated parallel to {1100} plane as similar to A-specimen. These fatigue cracks are deduced to extend by alternating shear on two intersecting prismatic slip systems at the crack tip. In D-specimen with (1100) surface and [1120] loading direction, the fatigue crack propagated along [0001] with prismatic slip. In E- and F-specimen with [0001] loading direction, these fatigue cracks propagated parallel to (0001) with {1012} twinning. As a result, S-N plots of each specimen showed strong orientation dependence.
