Effect of Grain Size on Slip System Activity and Room Temperature Strain Aging in Commercially Pure Titanium Rolled Sheets

Commercially pure titanium rolled sheets with different grain sizes of 20, 50, and 80 µm were applied to tensile tests to investigate the effects of grain size on the relationship between mechanical properties and activities of slip systems. While the ductility was independent of grain size, the activity of first order pyramidal slips and second order pyramidal slips decreased with decreasing grain size. In addition, grain boundary sliding was found to contribute to ductility when the grain size was small. Prismatic slips were activated in all of the specimens when yielded. Activity of pyramidal slips increased with increasing strain and decreased with decreasing grain size. Tensile tests were interrupted and slip lines were observed after the unloading in this study. Yield stress increment was observed when reloaded in interrupted tensile tests, but not in immediate reloading tensile tests. We found room temperature strain aging in pure titanium sheets. Yield stress increment increased with increasing strain.