Motoaki Morita

Analysis of Crystal Rotation by Taylor Theory

Simple shear along specific slip plane in polycrystalline and rotation of grains was discussed. The Taylor theory was applied to bridge between macroscopic deformation behavior and crystal plasticity and to evaluate the orientation distribution. Its theoretical solution can hardly satisfy all of boundary condition and plastic dynamics so that the condition of dynamics was simplified and relaxed in the analysis. The path of crystal rotation due to slip deformation was quantitatively predicted by Taylor theory and gave an advantage on understanding of deformation texture. The analysis method can be applied to polycrystalline materials. Although good evaluation was available in fcc and bcc where the orientation distribution fitted well, no good fitting to experimental result in hcp materials was obtained.

Analyses of heterogeneous deformation and subsurface fatigue crack generation in alpha titanium alloy at low temperature

Subsurface crack initiation in high-cycle fatigue has been detected as {0001} transgranular facet in titanium alloys at low temperature. The discussion on the subsurface crack generation was reviewed. Analyses by neutron diffraction and full constraints model under tension mode as well as crystallographic identification of the facet were focused. The accumulated tensile stress along may be responsible to initial microcracking on {0001} and the crack opening.