Heat treating is the process of hardening the steel. To hear most people talk about it you’d think it is a science. Well it is, but we’ll let the pro’s handle all that math stuff. Heat treating is the combination of hardening and tempering the blade.
Know if you are like me you don’t have a $1,500 heat treatment furnace. Do not let that stop you though, for a $10 bag of charcoal, a grill, and a way to supply a constant flow of air then you are all set. All and all to harden the blade heat it until it is non-magnetic and quenching it oil. Different steels have different temperatures at which they hit critical temps (non-magnetic) and are primed for quenching. Now you can go looking for a fancy chart that has steels, temps, oil temps for quenching, etc. There is an easier way though. Grab a magnet and once the blade is evenly heated and glowing red touch it to the magnet. If the blade does not stick to the magnet then dump it, straight up and down, into the oil. Ta-da! Your steel is now hard as a rock and more brittle than a child’s dream. Don’t fret, we’ll get that dream back.
Next what needs to happen is we need to temper the blade. This is fairly less intimidating than hardening. All you really need is an oven, and hopefully you don’t mind the smell of burnt oil throughout your house. Actually, I recommend you do this outside somewhere. A convection oven is awesome when it comes to tempering. Heat the blade back up to around 400 degrees and leave for around 2 hours, and this should take the stress out enough that if you were to drop the blade it won’t shatter into the worlds largest jig saw puzzle.
As mentioned before, you can look up the charts, get a thermo-gun, proper oil heating apparatus, and a rockwell hardness tester. Or if you don’t really want the spend three grand then this is for you.