when is cobalt HSS not worth it?

 I just spotted some cobalt alloy deburring bits on ebay, used in hand-deburring tools.  That prompted this post.

Cobalt steel is often seen as an option (a step up from HSS) for drill bits and sometimes other cutters.

Is it worth the extra money?  How is cobalt alloy different from regular HSS alloy?

 It's actually quite simple: cobalt alloy steel raises the temperature at which the steel begins to lose the high hardness which enables it to cut other steel. That's it.

 One thing cobalt does not do, is increase cutter life at normal temperatures. It does not make the steel harder, so it won't wear any different from regular steel.

 But if you like to abuse your tools and run them at high temperatures (without coolant or cutting oil), then cobalt will let you get away with it more often.

 And now you should understand why I was prompted to write this article: using cobalt alloy for a hand cutting tool does absolute fuck-all for you except raise the price.