Can one fairly easily harden/toughen steel?

[nightjar]

I had a 3.5kg Calor gas cylinder with a hose that fed a torch with interchangeable nozzles, varying from needle point (for soldering) up to

50mm diameter. For hardening lathe tools, any of the three largest nozzles would do.

[Roger Hayter]

Tines folded into a vee section may be a good compromise.

[Steve Walker]

I bought a similar torch for some silver soldering - when the regulator is turned up to 4 bar, it'll give 110 kW though! It needs a *large* propane bottle though - a small one cools too rapidly and stops gassing off fast enough.