Patent ID: 8293032

Claim:
A titanium alloy bolt having a head and a portion to be threaded and extending from the head, the bolt being made of a Ti—Fe—O (titanium-iron-oxygen) alloy, having a tensile strength of at least 800 MPa, and having a screw thread formed on a portion thereof, wherein the Ti—Fe—O alloy is a composition consisting of iron content of 0.6% by mass, and a combined oxygen content and nitrogen content of 0.24 to 0.44% by mass, with the nitrogen content substituting for up to 0.05% by mass of the oxygen content, the balance of the composition being titanium and unavoidable impurities, wherein the bolt includes a larger diameter portion with diameter D and a shank portion having a diameter d, wherein a relationship between the diameter D and the diameter d is expressed by a formula (D 2 −d 2 )=0.1×D 2 , wherein the threaded portion includes bolt roll marks.