24" long allen wrench

[Kevin in California]

Oh oh, Kevin gets put on the spot.
Well I don't know what the composition of the steel is used in the allen wrenches. We pretty much know they are not as hard as a file. That is most likely because the carbon content is lower than the steel used for files. All that to say, you may not get it any harder than it already is. Hardening you can easily do with a torch. (hard to do with a propane torch, but you may be able to cause it is a small piece of steel). Bring the steel to an orange to bright red, and quench it fast in water (you don't need an oil quench for this). Drawing the temper is a bit trickier because you need to know what steel you are working with do really do it right, but, if you can try putting it in your kitchen oven at 400 degrees for two hours, take it out and let it cool down to about 150 and put it back in for another 2 hours, then let it air cool. For file steel, you'll end up with around 61 to 62 RC hardness. My guess is it will be less for the allen wrench, but it may come out harder then what you get when you buy it. Steels vary by carbon content and alloys. What we know of as mild steel has a very low carbon content and won't harden at all.
Run a file over the wrench and see what it does, then try the hardening/tempering and run the file over it again and see what it does.
there you go.

Kevin

[Dave Bagwill]

It would be easier to weld a short piece of the wrench to a rod, as Herman suggested?

[ken cierp]

I think the sleeve/tube is important otherwise it will be like a noodle. That hex rod has .015% carbon content

[Kevin in California]

High carbon steel, like 1095 is .95%, a big difference