I made a double ended chuck key to fit both of my chucks a few minutes ago
and I'd like to case harden the square drive ends. The steel I used is
12L14 because that is what I had on hand.

I have some new formulation Kasenite and access to an OA torch. I understand
a carburizing flame can harden mild steel and of course so can Kasenite.

Which would be the better choice?

Thanks,

Wes