Cup Drawing of Strongly Textured Titanium Sheets.

Abstract

Commercially pure Ti sheets having a strong recrystallization texture were subjected to cylindrical cup drawing tests, and strain distributions, hardening behavior and microstructural changes developed in various parts of the cups were investigated in detail.It was found that, due to the presence of the strong texture, deformation in the parts of cup flange was highly anisotropic. In the drawn cups, appreciable thickening and work hardening were observed in the transverse direction of the textured sheets, accompanied by extensive twin formation. On the other hand, in the rolling direction, in which only a little twinning took place, thickening and hardening were much smaller. Since constraints of the blank holder were preferentially imposed on the thicker part in the transverse direction, deformation in cup drawing might be most severe in the transverse direction. However, failure of the cup wall did not occur in this direction, but in the rolling direction. It was suggested that the plane strain fracture strength in the wall part in the initially transverse direction was significantly increased by enhanced twinning due to the particular stress state in cup drawing.