Cobalt for Stainless Steel Cobalt drill bits are incredibly strong. They can be operated at much higher speeds than a standard HSS drill bit. The ability to withstand heat means that cobalt bits perform for long periods without cooling or the need for cutting fluid.They are most often used to cut through hardened and abrasive materials. Cobalt bits are able to cut through the most hardened metals, including bronze, cast iron, stainless steel and titanium. They are also able to cut through weld seams.The cutting edge on a cobalt bit should last for longer than a standard HSS bit. Like other HSS bits, they are corrosion-resistant, which means they should retain their condition in all storage and usage conditions they’re likely to experience.