"Kori" wrote in message
...
When I am making a tool bit out of tungsten carbide, do I have to keep it
cool? Does heat change it's hardness, or does this just apply to tempered
steel?

You don't have to keep it cool. It can glow red without suffering harm.
However, a brazed-on carbide tool bit will fall apart long before it gets
red, because the brazing material will melt.

Ed Huntress