EFFECTS OF β STABILIZING ELEMENTS ON SOLID SOLUTION STRENGTHENING AND TWINNING DEFORMATION AT ROOM TEMPERATURE IN α-TITANIUM

摘要

To obtain fundamental information used for improving mechanical properties in α-titanium, effects of Cu and Cr, both of which are the β stabilizing elements having relatively large solubility in the α phase, on solid solution strengthening and twinning deformation were investigated using grain size controlled 1mm-thick sheets. Solid solution strengthening effects by Cu and Cr are the same level and stronger than that of Al, which is believed as the most effective metallic element for strengthening the α phase. The result can be explained by the change of lattice parameters. Observations for the specimens tensile deformed by 5% elongation reveal that up to lmass% of Cu addition slightly suppresses twinning deformation while up to 0.5mass% of Al clearly suppresses twinning. Up to 0.2mass% of Cr addition does not affect twinning and the average number of twins per grain is almost the same as that in pure titanium.