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Post by Deleted on Jan 13, 2008 16:48:36 GMT
OK, so i heard something today that has made me a little nervous about quenching blades. apparently, when you quench a blade in oil, it absorbs the free carbon atoms as the steel cools. this has presented several problems. first, if you use a high cabon content steel to begin with, 1060 or above, will it absorb too much carbon to still be useful, or will it matter? also i guess it only case hardens the outside, making it really hard and brittle. would tempering at 400 degrees F for an hour even be hot enough to give the carbon a uniform composition? Or is it that the tempering process doesn't change the structure of the molecules? So, should you just Quench a higher carbon steel in water, then temper, or should it be quenched in oil?
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Post by Matt993f.o.d on Jan 13, 2008 18:42:21 GMT
No it doesnt. Quench away.
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Post by Deleted on Jan 13, 2008 20:55:18 GMT
The steel doesn't absorb anything in the quench, where did you hear that from?
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Post by Deleted on Jan 13, 2008 23:56:04 GMT
To tell you the truth, I heard it on Mythbusters
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Post by themaster293 on Jan 14, 2008 0:44:51 GMT
I heard that on Mythbusters too!!! Just last night in fact.
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Post by Dan Davis on Jan 14, 2008 1:01:04 GMT
So? I heard this morning that Miss America was dropping by my shop and bringing Jennifer Aniston along for the ride.
Doesn't make it true.
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Post by themaster293 on Jan 14, 2008 1:39:30 GMT
It is the fact that the Mythbusters team are very experienced scientists, and that most of the stuff that they say is true. They have been wrong before, but it is very seldom that they are wrong.
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Post by Deleted on Jan 14, 2008 3:00:53 GMT
It is the fact that the Mythbusters team are very experienced scientists, and that most of the stuff that they say is true. They have been wrong before, but it is very seldom that they are wrong. They may be scientists about stunts and prop building, but they sure as $@#% DO NOT know about blades, blademaking, metallurgy, or anything basically having to do with blades other than THEY ARE COOL AND THEY CUTS THINGS GOOD. I would not let someon with a PHD in pediotry take out my appendix.
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Post by rammstein on Jan 14, 2008 3:12:48 GMT
I think we're going to need some proof rather than blatant insults before we can believe you.
Frankly, I don't disagree with you, but why not back up your claims with facts rather than comments like "they sure as $@#% DO NOT know about blades, [etc.]." It's insulting, it's inflammatory, and it doesn't help your argument.
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Post by Deleted on Jan 14, 2008 3:22:46 GMT
Watch the show, if you know much about blades you will see everything wrong. They test things out OK, and the entertainment value is good. It's on again on Saturday Ramm, for you, i'll take notes. Watch the hammer episode too, that was a pile of useless false info. So? I heard this morning that Miss America was dropping by my shop and bringing Jennifer Aniston along for the ride. Doesn't make it true. How can that be? I heard they were coming to my shop:).
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Post by Matt993f.o.d on Jan 14, 2008 10:46:41 GMT
The fact that Sam and Dan both make blades for a living should be evidence enough for you guys to believe what they say.
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Post by oos3thoo on Jan 14, 2008 14:07:39 GMT
Hmmmm... My thoughts about myth busters are kinda low. When those Teri, Jamie and whoever try prove myths "wrong", human potential and fitness is always seems to be tested on seeing how hard they (They being the mythbusters) can hit things. As if humans aren't any stronger than they are. And on occasions getting a local "Professional" to be put on the same level as a legend.
You better know what I am talking about... I hate re-explaining.
I love the mythbusters but they know nothing of blades. Just math and science, which aren't always enough.
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Post by Dan Davis on Jan 14, 2008 15:47:15 GMT
Get real, people. Anyone who uses "mythbusters" as supporting evidence for any point of argument is essentially using the Hollywood smoke and mirrors department to prove their point. Based on that argument I think I'll go out, jump off a moving train and land on my feet, then engage seventeen bad guys in a gunfight using my .44 Magnum six-shooter. Of course I will kill them all without reloading once and walk away in my unrumpled silk suit that didn't suffer a single tear or broken button.
The two main characters on Mythbusters (yes, I said characters- these guys are actors) have as their resume that they have been doing special effects for movies for years. This does not make them scientists; it simply makes them good showmen.
One of the minor characters has as his resume the simple fact that while in college he built a robot in his garage for a show called battlebots. This apparently makes him an universal expert on all subjects.
Another of the minor characters has as the shining point on her resume that she went onto another Discovery Channel show (Monster Garage) as an automobile builder and caused all manner of trouble because she behaved as a complete ass. Another universal expert who we should believe explicitly when she cannot reproduce a poorly understood occurance.
The third minor character apparently has the sterling qualities of being able to use hand tools and the desire to be a guinea pig under the most humiliating and degrading circumstances. A source we all should worship and believe.
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Post by Deleted on Jan 14, 2008 15:58:08 GMT
The third minor character apparently has the sterling qualities of being able to use hand tools and the desire to be a guinea pig under the most humiliating and degrading circumstances. A source we all should worship and believe. Shoot, if i wanted to watch people degrade and hurt themselves and each other, i'd watch Jackass.
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slav
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Post by slav on Jan 14, 2008 16:24:29 GMT
I'll venture to say that I know almost as much [maybe more] about the principles of physics than they seem to on the show. And I know for a fact that I am more knowledgeable than both of them about blades and firearms.
But then again maybe It just seems that way because they intentionally dumb it down for the lay audience.
I've gotta admit though, those guys have the best jobs in the world. And they damn well get paid for it too!
Reminds me, anyone remember Junkyard Wars? I'll have to bring that up in the Cafe.
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Post by Dan Davis on Jan 14, 2008 16:27:01 GMT
To answer the original question: OK, so i heard something today that has made me a little nervous about quenching blades. apparently, when you quench a blade in oil, it absorbs the free carbon atoms as the steel cools. Oil is a complex hydrocarbon chain; there are no free carbon atoms involved. Even when the oil burns off it forms carbon dioxide and carbon monoxide, still no free carbon atoms. this has presented several problems. first, if you use a high cabon content steel to begin with, 1060 or above, will it absorb too much carbon to still be useful, or will it matter? Carbon absorption values are expressed as a curve based on temperature and time of exposure. The resultants are depth of migration over time. In order to case-harden any steel down to a depth of one-two microns requires a prolonged exposure to PURE CARBON and heat, on the order of 3-5 minutes. The process for Pack-hardening steel actually takes HOURS to complete. By comparison, the actual duration of a quenching process is 1-3 SECONDS during which the metal is rapidly cooling down. Any carbon that happens to be first broken down from the hydrocarbon compounds into atomic purity and then absorbed into the steel could not possibly penetrate past the firescale before the steel was too cold to absorb anything. Thus, this presents absolutely no problems whatsoever and will have absolutely no effect on the steels. also i guess it only case hardens the outside, making it really hard and brittle. would tempering at 400 degrees F for an hour even be hot enough to give the carbon a uniform composition? Or is it that the tempering process doesn't change the structure of the molecules? Case hardening aside (which doesn't happen), tempering does absolutely nothing for carbon composition or carbon distribution. It seems you have a gross conceptual error on the function and purpose of tempering. When you raise steel above it's critical temperature the structure of the iron molecule changes. It shifts from a body-centered cubic structure composed of nine iron atoms to a face-centered cubic structure composed of 14 iron atoms. You can see the obvious here; that 14 is greater than nine and some iron molecules decompose into elemental iron in order to form the larger, empty boxes. The boxes formed by the iron molecules are now empty and larger, leaving spaces where carbon AND ALL OTHER ALLOYING ELEMENTS can migrate in and fill. When you cool the steel slowly, the lattice reverts back to it's original structure and the smaller boxes are filled with an iron atom.When you cool the steel rapidly the shell of the box shrinks faster than the carbon or other elements can be displaced and the carbon forms martensitic steel crystals. Now here is the kicker: martensite, ferrite or austenite are regular crystalline shapes but during each quenching process some carbon is fully trapped, some is completely ejected, and other carbon atoms are trapped in ever state between. The "between states" carbon atoms create stressed, irregular crystals that cause steels to crack and fail. Tempering as a process simply adds energy to the crystalline iron molecules, allowing the bonds of those molecules to expand and "relax" without causing state transformation. This in turn allows the carbon (and all other similarly trapped elements) to either migrate into or out of the stressed molecular structures. this results in a molecular change into fully-formed martensite or fully-formed ferrite, either of which is a regular crystalline structure and inherently stable. This should also explain why tempering is a function of time as well as temperature, since you need to both relax the molecular bonds and give the trapped elements TIME to migrate. So, should you just Quench a higher carbon steel in water, then temper, or should it be quenched in oil?
No, each steel is formulated at the mill and should be quenched as directed by the manufacturer.
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Post by Deleted on Jan 14, 2008 16:39:19 GMT
Dan, you said right:D. Only one little thing, alot of times the manufacturer's quenching directions are based on large LARGE cross sections, so you can get away with using oil for some water quenching steels with a higher success rate than with water. Plus when you factor in oils like Parks#50, which is damn close to being water in oil form but a much more even heat transfer, it's get's tricky but i am just getting overspecific. They say quench 1095 in water, but alot of times that GUARENTEES cracks, so you can get away with great hardness with much less sadness:) in oil.
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Post by Dan Davis on Jan 14, 2008 17:12:50 GMT
Very true, but those determinations only come over time and with experience, and it seems as if Ben is working on both of those Interesting aside for everyone else: Iron undergoes phase transformation into austenite and back into ferrite whether or not there is carbon present. A large part of the hardening which is attributed to carbon content of the steel is actually a function of molecular structure and accretion effects in iron. Accretion is what causes grain growth in steels and also what causes the lammellar plate structure of normalized or annealed steels. If properly quenched, iron will form long chains of regular molecules having a much higher strength and hardness than normalized iron. In other words, if you quench wrought iron it becomes very hard and makes a decent sword. The aforementioned long chains of iron molecules become very flexible as they grow in length, which is why wrought iron made such great buggy axles and steamship drive shafts. The function of the martensite crystals in hardened steel is to break up those long, regular strings into much shorter pieces while allowing them to remain regular and parallel. shorter means less flexible which means harder. This is the primary hardening effect of carbon and should help explain why such a small percentage (six tenths of one percent in 1060) can make such a huge difference in the characteristics of iron. Another interesting aside (and correllary):You CAN put a hamon on wrought iron and this is why it works. Another interesting aside: when you quench a piece of steel not all of the carbon forms martensite, and when you temper you reduce some of the martensitic structures further. It therefore stands that if any given steel has a lower carbon content it must therefore be heat treated more severely in order to form the same percentage of martensite as a similar alloy having a higher carbon content. This is why you sometimes here from smiths that some steels are more "forgiving" than others; You can quench some steels longer with higher temperature differentials because the formation of martensite (and it's ugly stepsisters) is inherently lower and therefore stress buildup is less rapid.
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Post by Matt993f.o.d on Jan 14, 2008 18:33:32 GMT
Fascinating info, Dan. A lot of smiths would faint at hearing you divulge such incredible knowledge for free!
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Post by Deleted on Jan 14, 2008 18:38:13 GMT
Fascinating info, Dan. A lot of smiths would faint at hearing you divulge such incredible knowledge for free! Who cares about jerks like that? Info should be shared freely to further the entire craft as a whole, anytime someone neglects to share info, they are doing the craft a serious injustice.
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