Quench question

To quench a knife forged from a file,can i use an oil quench,or will i need to quench in water or brine to get a good hardness?Thanks.

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Files are very high carbon steel. Betwen 1.2% and 1.4% carbon content. Water or brine quenching can shatter or fracture them. Oil works very well. Try a high temp vegetable oil or mineral oil.
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Make sure you have a good file. Some are case hardened and will not make a good knife.
As Ernie stated, use oil and heat it to about 125 degrees before you quench. I use automatic transmission fluid. It will flash (lite on fire) so be prepared for that.
Bob
On Fri, 26 Dec 2003 07:32:48 -0600 (CST), Lil_Red snipped-for-privacy@webtv.net (Cockahdewalk Youbetcha) wrote:

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Thanks,Ernie and Bob! I have quenched 1095 in veg oil with good results,but i half-rememer reading somewhere someone claim that the steel in files wouldnt harden very well in oil.Thanks for the help.
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oso snipped-for-privacy@yahoo.com wrote:

Bob, ditch the tranny fluid. There are metalic soaps in tranny fluid to prevent foaming, and they will contaminate the steel at quench temperature. Same goes for motor oil and almost all the other 'automotive' petro products, bad news for hot steel.
Charly
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Charly,
I have been forging knives for ten years and do my own destructive testing to determine the quality of my knives. I have never had a problem using tranny fluid. I have discussed this with about 2500 other knifemakers over the years on the Custom Knife Directory forum of which there are some pretty famous and respected knifemakers and nobody has ever said anything about metalic soaps. Nobody has ever complained about contamination of their blades that I know of.
Can you elaborate on how you know of this? As I said, I am happy with my heat treatment as it is but if you can shed light on an unknown, I will change my process if I can exceed my own tests as a result..
Currently, I can make knives that will pass the journeyman and the master bladesmith tests given by that ABS and my personal tests are more demanding. I am really quite surprised that there could be a problem but I am open to hear what the effects of these contaminates are.
Bob
On Fri, 26 Dec 2003 20:45:39 GMT, Charly the Bastard

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On Fri, 26 Dec 2003 19:47:52 -0600, oso snipped-for-privacy@yahoo.com wrote:

[blah blah]
How many knife makers really know shit about metallurgy ?
Talk to someone who works in the automotive industry - particularly for gearbox production. My car (15 years old) has 1/4million miles on it and is still going fine. My first car barely made it to 100K. There's a reason for this, and understanding the subtler points of long-term surface contamination is a big part of it, let alone using these same oils for heat treatment.
I'd quench files in water if I were making scrapers or some sorts of knife, but for general knives or anything that's likely to take a pounding, then go with oil. The cracking problem is easy to over-state, but it can happen.
-- Klein bottle for rent. Apply within.
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Are you saying Charly is wrong or that I don't know what I am doing?
Please explain further.
Bob
On Sat, 27 Dec 2003 04:03:29 +0000, Andy Dingley

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oso snipped-for-privacy@yahoo.com wrote:

Slow down, Bob. Anti-foaming agents are usually lithium-based metalic soaps, and they will induce surface brittlness in certain alloys, especially the chrome-heavy ones like stainless. (damn stickyspacebar...) Old motor oil contains combustion formed acids, and sulphate compounds that the foundries work very hard to remove from the steel. I don't know what alloys you work, but that kind of stuff I don't want in my work. I use USP Mineral oil, Vet-grade, which is about a 20-weight at room temp, and it has produced consistent and reliable results for every oil-hardening steel that I normally use. YMMV
Charly
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Charly,
I just get a little twisted when people challenge the knowledge of people they don't know. If is fine to say they disagree with something but to just make a blanket statement that knifemakers don't know shit about metallurgy is irresponsible. We may not know EVERYTHING but then again, we don't need to know everything. We need to know enough to make a quality knife, not necessarily how to get and extra 150K miles out of our cars.
As I stated earlier, my knives pass the tests I put them through and that is better than the factory knives can do. I would take one of my knives into a situation where I had to depend on the quality of the knife before I would take any factory knife.
When you said to ditch the tranny fluid, I responded with a request for more info and admitted that there could be something better and wanted you to share your knowledge.
I have actually used mineral oil in the past. I used it at another knifemakers shop and did not like the results. Now, I had never used it before and had not done all of the tests I would do to get the heat treat correct like I would in my shop. I just followed the heat treating guidelines the other knifemaker used for his knives. The result was a knife that did not pass my tests, so I never went back to it afterwards. It now may need another look. If it can make a better blade than what I am making now, I will switch in a second. If I can't improve on my end product, I will stay with what is working now.
I appreciate your pointing out the potential issues tranny fluid could cause.
I just wish people would talk to others here like they would talk to them face to face. There was no reason for that rude reply, it could have been done politly and added to the conversation, taking the topic to another level. Instead, it is just annoying. To jump into a conversation with smart ass remarks really needs to be backed up with something more than just "cause I said so" arrogance. He said he would quench files in water but that creates a vapor barrier and does not do as good a job as quenching in preheated tranny fluid, proving he does not know what he is talking about. Using files is usually done by beginners and experienced people use new steel of thier choice so they can more accurately heat treat for performance. Sounds to me like he is trying to sound like he knows what he is talking about but really just heard a car guy say something similar.
Thank you Charly for explaining your reasons.
Bob
On Sun, 28 Dec 2003 14:34:13 GMT, Charly the Bastard

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On Sun, 28 Dec 2003 11:26:15 -0600, oso snipped-for-privacy@yahoo.com wrote:

Well if you don't like it, lay off the sarcasm from your side, "I have just learned that there are NO blacksmiths in this world that cannot forge weld. " then you might not get it thrown back at you so much.
I don't understand metallurgy. I say this, because I have friends who teach the subject and I know I don't know a fraction of what they do. I've worked in car plants and press shops (building SPC measuring rigs) where how to make something last 10 million cycles was a done deal and now they were pushing for 100 million. These are the people who really care about metallurgy, even the subtle stuff that doesn't show up in normal service.
Then you tell us that backyard smiths know all there is to know abot quenching oils on the basis of "I haven't had any problems so far". All this, from a trade that you don't think even needs to know how to forge weld.
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The sarcasm was not meant for you. The person it was directed at is very capable of defending himself and made his point of view known so don't feel like you need to help him out..
As for you, you admitedliy do not know metalurgy so why are you even bothering to try to tell others anything?
I haven't had any problems so far is correct and I TEST my blades, did you miss that or did you not understand that? I was not sarcastic to the guy that told me about potential problems, I pursued his reasons for saying so. I did not say that backyard smiths know all there is to know about quenching in oil. Re-read the post.
Just because you know someone that might know something does not give you any knowledge at all and therefore you look like a fool getting onto this discussion.
What have YOU done to give YOU any insite into this topic at all?
On Mon, 29 Dec 2003 18:52:50 +0000, Andy Dingley

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oso snipped-for-privacy@yahoo.com wrote:

Charly
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As a new person to this group that is thinking about getting involved in black smiting, a couple of good answers to this question would be much better then these flame wars you folks seem so will to wage. I have been around Usenet for over 8 year, and it never ceases to amaze me, how people get sucked into these battles of the egos.. So, as Cockahdewall Youbetcha asked, Oil or Water?? Thanks in advance, and please keep the flames in the forge:-) Doug

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Doug,
It all depends on the steel.
If you are buying steel, it is easy to tell what to use.
If you are using good quality files like Nicholson, they are 1095 steel. You would use oil heated to 125 degrees for your quench.
If you are using O1, you would also use Oil
If you were using W1, you would use water.
If you are using leaf springs they can be 1095, 1084 or 5160. All would use oil but the tempering is different.
Do you know your steel? If not, I would use oil and then test your results. If they are not satisfactory, normalize and then try again with water. TEST again.
Bob
On Mon, 29 Dec 2003 22:32:42 -0500, "Douglas R. Probst"

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"Douglas R. Probst" wrote:

Well Doug, it depends on what kind of steel the file was made from in the first place. Nicholsons are made from W-2, which is a water-quench alloy. Was it a Nicholson? Or was it some no-name from China made from Bhob-knows-what kinda floor sweepings?
Quench is about the rate of temperature drop in the workpiece. Brine (saturate saltwater) is the fastest, then pure water, then oil being the slowest. When steel is heated past about 1475 degrees, the carbon 'goes into solution' in the matrix, and forms a carbide film around the individual ferrite crystals. When you quench, the rate of temp decrease has a controlling effect on the final size of the crystals. The faster you cool, the smaller the grain size, and the more carbide is exposed at the edge. It's this carbide that is the hard part, the ferrite stays soft, so the more carbide exposed in the edge, the better the blade will retain sharpness. This is the rule for plain carbon steels, the SAE 10xx series. When you add alloying agents, like chrome or molybedamned or vanadium or manganese, then the rules change, and you start needing oil because a fast quench can produce internal stresses capable of actually tearing the work apart in the tank. (I have a water-quenched piece of SAE5160 on the wall to remind me of this, little hairline cracks all through it. But damn, a file won't touch it, so it went above Rockwell C-65.) The quench will push the work to 'full hard', then the draw, a low temp reheat, will relieve the internal stresses at the expense of some of the hardness. Final temper is a compromise between absolute hardness and the ability to absorb deflection loads, like a spring, or repeated impact loads, like a hammer. Clear as mud, yes?
Charly
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Just to make sure, did you catch the idea that your files may or may not be "hardenable" steel thru and thru? If they are simply case-hardened lower carbon material, they won't work well. Case hardening is usually only "skin deep", so if I were you, I'd take a sample of the file I'm going to use and grind ALL the teeth off, plus 020" or so and then see if that material is hard or not. Alternately, you could heat a sample to non-magnetic and then quench it in water. If it gets brittle when so quenched, then it will work for you.
I'm a general blacksmith, not at all a knife maker, but with all the work that goes into a blade, I think I'd invest in known, brand new material for my knife stock. In the end, the cost of the stock will be but a small part of the total "cost" of the blade.
Pete Stanaitis ------------------
Cockahdewalk Youbetcha wrote:

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Now those last 3 posts were fantastic! All 3 gave good information that allowed us beginners to learn something. Thanks very much, and have a safe and happy new year to all! Doug
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Can we get back to fighting now??? :)
Les
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