I gotta ask... is that drill head decorated? Or is there a purpose for all those welded-on lines and dots?.
Them lines are what what is known in the welding trade as hard-facing
It's put on there to postpone wear to the actual surface of the cutting head.
Excavator buckets and bulldozer blades typically have the same thing.
It's done by running a bead of weld from a special hard-facing welding rod all over the surface to build it up.