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from Knife Chat Jan 16, 2009

[m_brothers] blade warping -> straightening?
[markb] Will the edge burn in an oven electric controlled temp?
[Finnr] I leave the edges about the thickness of a dime when hardening
[brucegodlesky] warping?? normalize normalize normalize
[steve sells] most the time by leaving a little extra thick at edge we can avoid burning
[steve sells] thin sections will heat faster than thick
[steve sells] they also loose heat faster and can cause a failure in the hardening precoss from that too
[m_brothers] same here art, about a dime, i didnt call it a dime, i called it about 1/16"
[brucegodlesky] Keep the blade moving back and forth in the forge
[steve sells] most warping for beginners is from using the hot blade to move the coal, or hitting lumps with a rake while the blade is hot in fire.
[steve sells] tell beginners all the time watch the blade when its hot it will move as ya hit it may not think about it while its covered by the coals when you hot the coals on top it, then it bangs the steel underneath too
[m_brothers] i mean after quench
[Finnr] have to have even heating
[steve sells] or shaking it too hard and fast inthe quench and hitting the side too don't worry about edge quenching at first, dip it tip first into the oil and move gently even heat, normalizing before the heat treat, after the grinding
[m_brothers] i mean i quench vertically, but I have a little bit of warping along edge, what can i do to even it out?
[brucegodlesky] sounds like uneven edge
[steve sells] when HT with 1095 many use 1500 - 1550F for a harden temperature. We have to get that temp to below 900F in less than 0.8 seconds to make it harden, BUT it doesn't actually get stiff until its about 500 F or lower. So between thats 900 F and 500 F temps we can still straighten a little with out messing up the blade or its heat treating process we started
[brucegodlesky] long as you're wearing glove s:-)
[steve sells] yes bruce, but I can't imagine anyone hardening in oil with out gloves, more than once anyway
[Finnr] flash ain't fun!
[brucegodlesky] sometimes I forget
[m_brothers] i've done it without gloves, just used likes 3ft tongs, lol
[brucegodlesky] sometimes I go a long time without a warp, other times they seem to breed
[Ted T] How deep is the hardening (penetration) when hardening, and then while drawing to desired temp!
[steve sells] hardening is totally dependant on 4 things, One is the steel used, another is grain size, the temps and quench
[Fionnbharr (finn:-)] If I am not mistaken I have hardened a 2 handed sword without gloves, but I might have been wearing them...
[steve sells] a 10xx series is shallow hardening steel, and anything with chrome in it will harden most the time all the way through
[brucegodlesky] V and Mn also, right Steve?
[steve sells] small grains, always preferred in blades may keep the hardening depth shallower than with larger grain sizes
[steve sells] there are also other additions like Vanadium and WTUNgston that also assist in grains size remaining small, and assist in hardening
[steve sells] MNH to a point makes it "medium hardening: as I can say it will make deep hardening, but these all work together
[steve sells] Yes bruce
[markb] aus forging
[steve sells] all US steel have Mn in them we have no choice unless we make out own
[LDW] What thickness of the cutting edge would be too thick to have the cutting edge not hardened with a 10 series steel after grinding, I am talking about an approximate thickness. I am assuming 1/16" would be fine, but I do not know for sure.
[steve sells] 1/16 is fine remember the de-carb zone when heating before the hardening its thin, but we want enough extra thickness to be able to remove that too
[brucegodlesky] I think with shallow hardening steels, a knife blade still hardens thru and thru
[Finnr] on salvaged steel it's better to go a bit thick for the first blade from a batch . You can make it thinner but not thicker
[brucegodlesky] it's when you start fooling with thick profiles , shallow vs deep shows up
[steve sells] yup To thin and even if ya don't burn the edge you will still have soft spots due to de-carbonization

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