I claim the ornamental design for a titanium nail, as shown and described.
FIG. 1 is a perspective view of a titanium nail, showing my new design;
FIG. 2 is a front elevational view thereof, the rear elevational view, left-side elevational view, and right-side elevational view all being identical thereto;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof; and,
FIG. 5 is a cross-sectional view thereof, taken along lines 5-5 of FIG. 3.
The broken lines in the drawings illustrate environmental matter that forms no part of the claimed design.