工業用純チタンの2軸引張り変形における双晶変形の結晶方位依存性

抄録

Orientation dependence of twinning in commercially pure titanium was determined under biaxial tensile stress conditions. {10\bar12}, {11\bar21}, {11\bar22} and {11\bar24} twinning occurred in equi-biaxial stretching depending on crystal orientation. Twinning operated only in the orientations where the resolved shear stress on the twin system was directed to the twin direction. Moreover, it was observed that twinning generally occurred on a highly stressed system with a larger Schmid factor for twinning. However, {10\bar12} and {11\bar22} twinning had a tendency to precede {11\bar21} twinning in the orientations where Schmid factors of these twinning systems were comparable. This suggests that {10\bar12} and {11\bar22} twins nucleate more easily than {11\bar21} twins. The planar anisotoropy of deformation twin density, which has been reported in biaxial stretching of commercially pure titanium sheet, is satisfactorily explained by the orientation dependence of both twinning and slip presented in this study.