Prevention of Seizure by Oxide Coating in Multi-Stage Deep Drawing of Pure Titanium Sheets

摘要

Long pure titanium cups with a high resistance to corrosion are formed by preventing seizure in multi-stage deep drawing processes of titanium sheets. The titanium sheets have sufficient ductility and high r-value for the deep drawing, whereas the seizure tends to occur during the deep drawing due to high reactivity with other materials. For the prevention, pure titanium sheets are treated by electrochemical and heating oxide coatings, because the coated titanium is not in direct contact with the die during the deep drawing due to the existence of the oxide layer. The effects of the coating methods and conditions and die materials on the occurrence of seizure in the multi-stage deep drawing are examined. Long pure titanium cups with the height which is 6 times larger than the diameter were successfully formed by using bronze dies or oxide re-coating.