My machinist friends don't support the "you can't hurt HSS by overheating"
philosophy. They agree it is much less prone to damage but recommend you
learn to grind without bluing.
Billh BRBR

A member of our AAW chapter is a metallurgist, and he explained to us that
bluing will NOT make a HSS tool lose its temper. I don't recall the temperature
that makes steel turn blue, but he said that HSS is tempered much higher than
that. You would have to heat it to "straw color" to take away the temperature,
and an aluminum oxide wheel is not capable of getting HSS to the "straw" stage.
Carbon steel tools are the only tools you can't blue without losing the temper.
-Jim Gott-
San Jose, CA