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Post by Deleted on Jan 24, 2008 20:07:59 GMT
About 3 minutes in, watch CAREFULLY what he does with the steel.
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Post by Deleted on Jan 24, 2008 22:36:44 GMT
hey, i was watching this just a couple of weeks ago...remember sam showing me that little "trick" (?) when i first visited him. the whole set of videos is actually pretty interesting, imho.
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slav
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Post by slav on Jan 24, 2008 23:02:37 GMT
So, basically he was comparing annealed, quenched, and tempered steel.
That was really neat. A good demonstration of the simple principles of "heat treating".
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Post by Deleted on Jan 24, 2008 23:21:37 GMT
Tempering removes stress in steel after quenching,also slightly softens the steel.You can use an old oven for this(I use with good results) For some types of steel freezing it may also improve their performance.
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Post by Deleted on Jan 25, 2008 0:46:43 GMT
So, basically he was comparing annealed, quenched, and tempered steel. Comparing normalised, quenched(hardened), and quenched(hardened) and tempered steel. Proper terms are key to understand what everyone is talking about. With proper terms everyone speaks the same language. For some types of steel freezing it may also improve their performance. Do you have any concrete evidence of this? I am not hound dogging you i have just yet to see anything credible on the subject.
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Post by Matt993f.o.d on Jan 25, 2008 10:57:42 GMT
Was there anything special about the way he put it into the water? He did it the same both times, with the piece of steel at an angle to the surface.
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Post by Deleted on Jan 25, 2008 13:44:45 GMT
No, just quenched it in water. With blades you have to go straight in, one side or the other might cause one side to cool a bit faster than the other anf pull the blade a bit to that side.
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Post by Dan Davis on Jan 25, 2008 14:28:46 GMT
Sam, Heat-treated steels with chromium content above 12% can develop chromium carbide particles which will only decompose under extreme heat (thereby killing the heat treatment) or under extreme cold.
This has become very popular in blademaking for stainless steels but it really only has a major, lasting effect when dealing with high-alloy large-volume castings like pump motors for nuclear power plants.
In other words, another perfectly valid metallurgical process converted to hype in the blade world.
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Post by Deleted on Jan 25, 2008 15:16:59 GMT
yeah Dan i thought so. it has only been around for a short while, so we still don't know everythng about it yet. Everyone seems to have jumped on that bandwagon though.
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Post by Matt993f.o.d on Jan 25, 2008 15:26:38 GMT
Hey Dan, where did you learn all this metallurgy?
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Post by Deleted on Jan 25, 2008 16:19:18 GMT
Like Dan Davis said I am working now with D2 steel which can be frozen to improve performance.I think it is not just hype.Many knifemakers recommend this process.
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Post by Deleted on Jan 25, 2008 16:54:36 GMT
Great vid. Thanks for posting. I had forgotten what the proper color for tempering was. Blue it is.
I wonder to what extend a tempered sword should reflect that blue color as a finished product. I have seen it in tempered SCA armor. I know some swords also reflect it. Does this mean lack of blue means no tempering?
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Post by Deleted on Jan 25, 2008 17:11:56 GMT
No.Different steels have different temperatures of tempering.Also the coloured layer(not always blue-different tempering temperature may give the steel other colours like for example gold)that appeares on the surface is not thick.You can easily remove it with polishing.
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Post by Dan Davis on Jan 25, 2008 17:20:10 GMT
Hey Dan, where did you learn all this metallurgy? I used to work on nuclear power plants. Back when I wasn't any sort of an engineer.
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Post by Deleted on Jan 25, 2008 17:41:03 GMT
No.Different steels have different temperatures of tempering.Also the coloured layer(not always blue-different tempering temperature may give the steel other colours like for example gold)that appeares on the surface is not thick.You can easily remove it with polishing. Very interesting. Since you can never be 100% sure of what steel you have and it would get even more complicated if you start forging different metals together, is finding the right temper color a matter of trial and error? or is there some way of knowing what color to look for when heat treating.
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Post by Matt993f.o.d on Jan 25, 2008 22:51:30 GMT
Crikey. I never associated metallurgy with nuclear power.
Yo Tsafa, when tempering, you see various colours appear on the blade. This is the oxide film which forms on the surface of the steel. Yellow is first. Purple and blue follow. Once the blade reaches grey, the heat treatment is buggered.
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Post by Deleted on Jan 26, 2008 4:59:41 GMT
Running the colors is a POOR way to temper any steel, especially blades. There is no specific color for each specific steel, but there are specific temperatures different steels need to be tempered. Lack of blue does not mean lack of tempering.
LET ME SAY IT AGAIN ALSO, RUNNING THE COLORS IS A POOR HALFASS WAY TO TEMPER.
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Post by Brendan Olszowy on Jan 26, 2008 13:44:56 GMT
I think knowing what temperature is required for your steel and just cooking it in an oven at said temp. would be easier than judging whats blue and whats purple. Also as or Smithy friends have stated repeatedly Tempering is a function of time as well as temperature, and I've got no ambition to hold a propane torch at 5.57" from the blade for 90 minutes.
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Post by Dan Davis on Jan 26, 2008 13:56:36 GMT
Also, bear in mind that the demonstration was made using short, narrow pieces of very thin steel that was through-hardened. Dimensions and degree of hardness are important factors.
The demonstration was great but hardly all-inclusive.
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Post by Deleted on Jan 26, 2008 15:02:32 GMT
The demonstration was great but hardly all-inclusive. Well hehe, just to get a ROUGH idea of the very basics:D.
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