G'day folks,
We have a good how-to on DIY PowerTorque special tools here; https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/33821/all/Victa_special_tools.html

I would add the comment, that quality sockets will not be case-hardened, but fully hardened and tempered Cr-Mo [Chromium-Molybdenum] AISI 41xx series alloy steel.

So long as they don't get hot enough from grinding to reach the Curie point [which is where a magnet will no longer stick to the socket], their heat treatment won't be affected significantly.
Not that re-heat treating is at all difficult for these steels, in any case.
Edit: FWIW, that's a simple heat to Curie point or dull red, oil quench to harden, temper by colour procedure.

Last edited by Gadge; 14/04/17 06:46 AM. Reason: Add HT info
Cheers,
Gadge

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