Study on edge cracking of titanium cold rolled sheet

Research Institute of Industrial Science and Technology (RIST), 67, Cheaongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do, Korea

Abstract

In this study, to understand oxygen effects on workability of titanium, edge cracking and microstructure changes with the oxygen content variations in the cold rolled sheets were observed carefully and discussed. The higher oxygen content of titanium sheet, the more the edge cracks occurred after cold rolling deformation. While the specimen containing low oxygen became fine grained structures after the cold rolling, the other high oxygen sheets consisted of relatively coarse and elongated grains. The fine-grained structures was assumed to come from an active twinning behavior, meanwhile the other’s elongated structures were due to the twinning suppression by increasing oxygen contents. In addition, distinct shear bands were appeared in the high oxygen sheets after cold rolling. The high oxygen contents may multiply dislocation density by suppression of twinning and promoting dislocation slips. The increased dislocations can also produce a concentration of strain, slip bands thus appears during the cold rolling deformation. These slip bands cause the edge cracking in the higher oxygen sheets.