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Old 11-07-2017, 12:51 PM
Max Grossman Max Grossman is offline
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Originally Posted by Pete VanderLaan View Post
why does dipping hot steel in oil harden the steel?
Why does it mess it up if you do it too many times.

What kind of oil?
I have been fascinated by the programming on cable issuing challenges to blacksmiths to make specific items, like sword blades in three hours.
When ya quench it, you cool the outside rapidly - think prince rupert's drops. then you temper it (aka anneal it) to get a bit of the stress out of the metal so it doesnt crack.

Some things are selectively hardened - say the blade of a stone cutting chisel is hard to cut through rock, but the end where you strike with a hammer has been tempered (softened) so it doesn't break from the hammer blows.

I've been playing with some air hardened steel to make jack blades, shear blades, and tweezer tips - it self hardens as it cools, which is better for the business end of glass tools since you lose the hardening when you overheat the tools.

to the OP - I would send it back to Shin, and tell him what's going on. If I were doing it, I would heat it, bend it, then properly heat treat depending on what part of the shear. But the heat treat depends so much on what steel he used! I quench mild steel in water (barely even hardens it) but would never do that to tool steel - unless it was a water quenching steel! See what I mean? Hard to know how to treat the metal till ya know what it's made of.
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