I worked for a axle remanufacturer - that's correct - the axles are
generally mild steel with a case hardening of .030 - .070" depending on
place of origin.

"Jordan" wrote in message
...
I just discovered auto axles - interesting stuff to machine.
Seems hard on the outside, for about 1/8 inch deep, probably due to oil
quenching when hot? Gives the tool a workout! Below that it's easier to
turn, more like mild steel.