new old guy question.

[redneck17]

just rejoined the forum after being gone for a few years. noticed alot of changes. going to be starting bladesmithing very soon and had a question for the wise men here.
Been doing some studying on making knives and am having a bit of a hard time finding info on the tempering process. i know this varies a bit from steel to steel. but say I was using 5160 from a car/truck spring and had heat treated it with 3 thermal cycles. how would I go about the temper to get the hard edge and soft spine thereby creating a blade that could handle a little punishment like chopping through hardwood?
Thanks. Josh

[BlissStreet]

I'll venture an answer. As I understand it, there are 2 ways of differentially heat treating a blade. One is to quench the edge, letting it cool faster then the spine (claying the blade or 'goop' quenching). The other is to harden the entire blade and then draw the temper along the spine using a torch or tempering tongs.

Fair warning though, I'm new to this and others here have by far more experience then I do. Edit: also, see the heat treat stickies.

[Nakedanvil - Grant Sarver]

Three ways actually. Differential heating, differential quenching and differential tempering. Of the three I have a preference for differential tempering in most things. This allows you to make the softer part a high strength, just lower hardness.

Differential heating is most easily done with induction or a torch.

[Rich Hale]

Welcome back Josh. Just have to wonder if you were to follow the full blade hardening and tempering routines for the steel you have chosen and then tested it to do the things you wish....And then for a good comparison try another one with the differential heat treating and see which one serves you bestg.....If you do this let us know and have fun.