Method of forming a highly-deformable titanium or titanium-alloy one-piece fastener

A method of forming a semi-tubular fastener, the method comprising steps of:

• inserting a semi-tubular blank precursor into a bore of a forming die, comprising an enlarged bore portion, and wherein:
• the semi-tubular blank precursor comprises a hollow tubular cavity extending at least partially into the semi-tubular blank precursor, and
• the semi-tubular blank precursor is formed of an ultra-fine grain titanium or titanium-alloy composition, having an average grain size of less than approximately 10 microns;
• inserting an insert tool into the hollow tubular cavity;
• applying a first axial compression force to the semi-tubular blank precursor after inserting the insert tool in the hollow tubular cavity;
• forming a cold-worked head section and an enlarged shank portion on the semi-tubular blank precursor, and wherein the enlarged shank portion corresponds to the enlarged bore portion, and the enlarged shank portion comprises a nominal shank portion, extending therefrom;
• inserting the nominal shank portion into a bore of a final reduction die;
• applying a second axial compression force to the enlarged shank portion;
• urging the enlarged shank portion into the bore of the final reduction die;
• reducing a cross-sectional area of the enlarged shank portion by approximately 2 to 5 percent;
• and
• forming a cold-worked shank section by reducing the cross-sectional area of the enlarged shank portion.