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Paring knife replacement

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tomrux:
if that is just plain old HRS all the heating up and soaking in the oven wont make a h'penny worth of difference to the hardness.

Tom R

superc:
Sigh, I lack a brinnel tester, so maybe so.

The ebay ad I bought it off actually had the words hot rolled carbon steel plate, so that raises the question why do you think it won't heat treat?

tomrux:
normal low carbon steel/mild steel does not heat treat. Just is.
needs to be particular carbon levels before heat treating has any effect.

From Wiki
"As the carbon percentage content rises, steel has the ability to become harder and stronger through heat treating."

.05% to .3% are normal/mild steel

above .3% gets you into heat treatable/high carbon steels.

go too much above 1.75% and you get close to iron. very tough but brittle.
all sorts of other elements are added to produce different characteristics.
Manganese, chromium, silicone and a chemists delight of others.

Tom R

superc:
So since the Ebay vendors very rarely tell (or know) the specifics of the plates they sell, most of us just do a spark test and confirm steel, then give it a try.  Not much all else we can do.  Regarding the shop knife, who knows.  It is hard and resists filing and getting the little hills and valleys out of the hand held bevel took a lot of stoning, more than some store bought blades have, that's about all I can say.  Yeah, I suppose I could give it a flex test with a breaker bar, but why would I do that for a knife designed for cutting string, tape or opening boxes.  Besides that tests the temper not the hardening.  So beyond noting machine tool marks were hard to file out, I don't know of another test without a Brinnel tester.

RussellT:

--- Quote from: superc on March 07, 2014, 11:17:27 AM ---I don't know of another test without a Brinnel tester.

--- End quote ---

You don't need to be able to measure the hardness accurately but comparing one sample with another might be useful.

If you took two samples - one annealed and one hardened - and put a ball bearing between them and then hit the sandwich with a hammer, the ball bearing would be punched into the samples with equal force.  Comparing the sizes of the dents would show which was harder.

Russell

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