differential quench vs differential temper

wrote:


Interesting. I recently purchased a band saw blade from a custom blade shop that was supposed to be "bi-metal". When I asked them for specifics I was told it wasn't really bi-metal but differentially hardened.
GA
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Same with old-timey swordsmiths; san-mai japanese blades, old time ax heads, some celtic swords- take a piece of 'tool-steel' and encase it in a softer steel soas to form the body of the implement with the edge presented.
Chas
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Sounds about like what I would expect to be needed. :/ Was hoping they had something easier figured out tho. ;)
If they can get that to work, they are a lot better at this stuff than I'll ever be. :)
Alvin in AZ
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Ecnerwal wrote:

Looking back through my copy of "Metallurgy theory and practice" I think the edge would only have to be kept below Ms (temp at which martinsite begins to form). So a setup which keeps the edge below around 450 F while the spine is at 500 F or better (exact temps and time held there would depend on alloy). Still difficult to do but perhaps a copper tube with water flowing through it in contact with the edge while the whole blade is in an oven at 500 F?
Sorry if some of you thought this thread was dead, but it takes a while for my brain to mull over new info.
ron
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Sounds really good to me! :)
Cool one Ron. :)
Contact between the cooler/coolant and the freshly quenched part is the only real tricky part of that?
Something metal that'll mold itself to the part like copper or silver that can be re-shaped when needed or something that's liquid-and-magnetic like that stuff they put inside loudspeaker gaps ...but can handle the temperatures.

No such thing as a dead thread, they just idle, only takes one more post to it and it's running all over creation again. :)

Same with everyone.
If thinking didn't take time, a chess game would only take seconds.
Alvin in AZ
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snipped-for-privacy@XX.com wrote:

I've been thinking on it for a while. The best I can come up with is make the whole blade bainite the reheat treat with a clay-coat on the spine. of course this is predicated on the assumption the clay will keep the spine from getting hot enough to lose the bainite. Which is something I have no clue on. I don't know if it would be possible to keep the spine hot enough long enough to form bainite without drawing the edge too far if done the other way.
ron
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On Sat, 11 Mar 2006 snipped-for-privacy@XX.com wrote:

Laminate a core with sides which air cool to bainite and do a shallow edge quench. Or do a full bainite and reheat the edge, just *really* shallow (as in 1/8" high) through induction or similar and requench.
--
Cliff Stamp
snipped-for-privacy@physics.mun.ca http://www.physics.mun.ca:80/~sstamp /
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An elementary question, Gentlemen, if you please:
Why not simply treat the whole blade to bainite and then, after quenching, coat all but about .25" with something like "Handy-Jig" [http://store.weldingdepot.com/cgi/weldingdepot/HANDIJIG.html ] then retreat for the martensite edge.
Or the other way 'round: treat the whole blade for martensite then coat the edge and retreat for bainite.
If I'm missing something, I'd appreciate being enlightened.
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