It doesn't have to be hard in the sense of holding an edge (no cutting
involved). But it doesn't seem to me (by intuition ONLY) that mild
steel would be "strong" enough. It seems like it would bend too easily.
But not-bending is a matter of tensile strength, yes? And mild steel
and hard steel have the same tensile strength, right? Or, is it a
matter of yield verses ultimate strength?
Bottom line - what should I use use to make a pry bar? (It will have
very specific geometry, so store-bought is not an option.)
OK, from what Ed & Tim said, I do want something harder than mild steel,
so that it won't "yield" as soon as mild steel would.
As to heat treating facilities, well, minimal - maximum heat capability
is propane forge. Obviously no automatic temp control.
As to what I'm making: it's for taking down tin ceilings. The ceilings
will be salvaged, so the specifics of the tool are needed to minimize
damage. The bar needs to be about 16" long, to reach over the back of a
24" tile. It needs to have a long taper, coming to a thin edge, to work
under the nails without distorting the tin. One edge needs to be 3/4"
wide to fit into a nailing space. One end will be straight & the other
have a 90 degree leg. It will be pulling out 1" long 16 ga nails, so it
won't have to be very strong - I'm thinking 1/16" thick (from trials
with a 1/16" thick putty knife).
If it wasn't for the length, I would re-shape the putty knife. Which
suggests brazing or silver soldering the knife on a longer handle - is
that doable? How about a 90 bend in it - I assume that would require
heating to bend, quenching, and tempering?