Which is tougher: carbide or titanium (for drill bits)?

Question

I need to buy a toughd drill bit to drill out two broken bolts. I've been recommended to get either carbide or titanium. I'm not sure what sort of carbide (tungsten?) or titanium or titanium-coated steel? Do they make diamond drill bits for this sort of thing?

Answer 1

Cobalt bits from Sears.They also sell screw extactors that work in a drill.-----Tech. Tip: If it is a broken exhaust manifold stud ,use a small socket the size of the bolt and insert it in the stud hole and use it for a drill guide so you do not damage the threads.

Answer 2

Tungsten carbide is often used on concrete cutting drills
Titanium coated drills are often a bit of a gimmick and don't always work as they should
If the bolts are in an engine you should be able to drill the bolts using a good quality twist drill
Forget diamond drills unless money is no object

Answer 3

Buy a cobalt left hand drill bit. Or two, if the size is small it's easy to break one whatever it is made of. Many times a left hand bit will start the bolt moving out while you are drilling.