According to Chris Lewis :
According to clifto :

I can picture how cooling would prevent brittleness. I can't imagine how
lubrication could prevent brittleness.

Mike's gotten confused. You don't use lubricants with grinding wheels.
Grinding wheels should be used on dry metal, they rely on both the
abrasion and instantaneous melting (the sparks) to cut. With hardened
steel or carbide, the melting does more of the cutting than the abrasion
does.

The picky may notice that there are _some_ grinding setups designed
to be cooled with a continuous stream of water. These are low speed
grinders (up to 200RPM or so) _mostly_ used for sharpening woodworking
tools - allows you to fine grind for long periods of time without overheating
and detempering the metal - in contrast with a standard bench grinder
that's usually running at 3600RPM with silicon dioxide (hard!) wheels
that will burn a chisel quite fast if you're not careful. Wet grinders
are not suitable for general metal shaping.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.