Oil over water quench?

R

R.C.Reichert

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Jul 26, 2008
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Have any of you heard of a quenching method involving water with a level of oil floating on the surface to give the quench a buffer zone? I heard that some old-timer bladesmiths used this method to give a fast quench without the severity of quenching in plain water or brine. I don't know the specifics involved in this and was wondering if anyone had ever tried it. Is that even a legitimate method for quenching or what?

I got a different question... If pearlite were to form in a blade not fully hardened in the quench, would it form close to the surface, or deeper in the core of the blade? My logic (whatever that is) says it would form closer to the middle where it didn't get a chance to cool fast enough. If that be the case, how would the presence of pearlite cause any trouble as far as edge-holding? Does this make any sense? Thanks, any help is appreciated.
 
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Hi RC :) The oil over water method is indeed a viable method of quenching for just the reason you mentioned. I first found it documented in my copy of Machinery's Handbook. I tried it once on the blade pictured but have since went to Parks # 50 with what I think are better results. I got some interesting results on the blade I used the oil/water method on. If you'll notice what looks like a thin double quench line moving up towards the tip at an angle just above the Hamon. Ironically this was clay coated and full quenched ....... once :confused:

Your pearlite question should be answered by one of our resident expert metallurgists that understand and can explain the process much better than I :o

P3130627.jpg



Edited to add, verbatim, the quote from Machinery's Handbook 26, pg. 490, paragraph 3 ..................

A water bath having 1 or 2 inches of oil on top is sometimes employed to advantage for quenching tools made of high-carbon steel as the oil through which the work first passes reduces the sudden quenching action of the water.



:cool:
 
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I don't know anything about that method. I have however used a double quench, first in water for a few seconds then immediately into oil. This brings the piece quickly past the pearlite nose then slower through the martensite transformation.I've done this on large parts and it took some experimenting to get the timing but it worked well.
I don't think you'd see much difference in pearlite amounts in a blade since you're quenching from both sides .If you were to quench a round bar there would be more pearlite and less martensite as you went from surface to center. Often with a round bar this is not a problem at all.
 
Logic tells as mete says, if it was oil under water it would work great but it is not possible to keep the oil under the water I suppose :).

I may be wrong but here is my guess.
When I look to TTT charts the temperature needs to fall very fast down just above to MS. After that you can take time to cool so any oil would suffice. So oil above water will not work if the oil is not a very fast HT oil for carbon steel. If it is a fast oil then you dont need the water under. So for any scenario it is not beneficial for any steel I guess. As I said, I'm wrong for most of the time but I'm pretty sure about this particular issue.

Instead, the method that Mete did seem much more promising for me..
 
galadduin said:
Logic tells as mete says, if it was oil under water it would work great but it is not possible to keep the oil under the water I suppose :).

I may be wrong but here is my guess.
When I look to TTT charts the temperature needs to fall very fast down just above to MS. After that you can take time to cool so any oil would suffice. So oil above water will not work if the oil is not a very fast HT oil for carbon steel. If it is a fast oil then you dont need the water under. So for any scenario it is not beneficial for any steel I guess. As I said, I'm wrong for most of the time but I'm pretty sure about this particular issue.

Instead, the method that Mete did seem much more promising for me..
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My thought would be that as the blade passes thru the layer of oil it cools. If the 2" layer of oil drops the temp just 200 or 300f it should take some of the stress of the water away, Plus the coating of oil residue on the piece from its trip thru should insulate the blade a take a bit of the severity water quench. Just my thoughts. I don't really know.
 
galladuin's comments make sense to me.

This topic makes me think of 1095. I picture the TTT graph in my head. 1095 needs a very fast quench to beat the pearlite nose. After that, however, continued rapid cooling can really pile on the stress... often resulting in the dreaded "ping". This is why folks will often use an interupted quench when using brine or water. Quench for a few seconds to rapidly pass the pearlite nose, then pull out to avoid unnecessary stress build-up, then back in the water. This is also the idea behind fast quench oils like Parks. Fast at the front end and slower toward the end.

Seems to me like an oil on water quench would be the exact opposite... slower as the blade passes through the oil initially and fast once it hits the water. Maybe the idea is to plunge quickly through to the water, then withdraw the blade near the surface to for continued agitation in the oil until Ms. Or maybe the purpose is similar to an edge-quench where the quench-depth is controlled so the edge is in water while the spine is in oil.

Hmmm... I think there are smarter people than me around here to give a more definitive analysis.

Erin
 
Wayne Goddard had told me about that method. I tired it a few times but stopped doing it. I can't remember what the results were. I've gone back to my old ways.
 
mete said:
I don't know anything about that method. I have however used a double quench, first in water for a few seconds then immediately into oil. This brings the piece quickly past the pearlite nose then slower through the martensite transformation.I've done this on large parts and it took some experimenting to get the timing but it worked well.
I don't think you'd see much difference in pearlite amounts in a blade since you're quenching from both sides .If you were to quench a round bar there would be more pearlite and less martensite as you went from surface to center. Often with a round bar this is not a problem at all.
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This is why I can't see pearlite being a problem in a cross-section as thin as a knife blade. Even a thicker one that was quenched in a slower oil and used a steel such as 1095. If it were a 2" thick bar of 1095 I could see why you would need a super fast quench to get to full hardness at the center. Otherwise wouldn't it be kinda like unintentional case-hardening? Maybe this is wrong, but aren't the industrial-grade and formulated quenching oils designed for just that? They are designed to achieve full hardness on parts that could be really big? Tell me if this is wrong thinking. I'm just a novice at this, so I'll take any criticism you have to offer. Thanks.
 
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Thought about it again and you may be right R.C.Reichert, I don't really know. I have a question on the subject, does anyone knows if the blade hits the oil and covered with oil then in the water cooling down, will the oil around the blade will break the vapor formations and helps the blade to cool down evenly or will it reduce the heat transfer rate insulating the blade and keeping the water away. Also carbonized oil will stick to blade steel under the water, so will it affect the cooling rate...
There are too much unknown to me. May be one of us have to test it and post the results. But testing is another monster for me, needs to eliminate too many variables, same shape test pieces etc. One have to have a couple days off to test this IMHO...
 
You need fast followed by slow. The oil over water is just the opposite.
The limits of how big a bar can be through hardened is determined by the 'hardenability' [dependent on chemistry] and the speed of the quenchant.Many applications do not require through hardened.
 
R.C.

Will you get SOME pearlite in W1 or W2? Yes!

However, with a fast quench (very fast oil, water, or brine, take your pick) it won't be enough that you'll likely notice it at all. Edge holding should be just dandy (assuming you did the rest of your job right).

Bear in mind that W2 has a long standing reputation for being one of the best edge holding steels available, and it has a practically identical chemistry to W1 (except the vanadium, which is there in a very small amount, and doesn't exactly have a huge impact on the cooling curve anyway).
 
It's kinda like Tai Goo once said in a previous thread...."heat treating in nothing but a big old can of worms". But in every can of worms, you'll be sure to get at least some "dirt". More or less, it's still a can of worms. Thanks for helping get all my worms in the can. You're advice is appreciated!
 
Raymond Richard said:
Wayne Goddard had told me about that method. I tired it a few times but stopped doing it. I can't remember what the results were. I've gone back to my old ways.
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FWIW, The steel in the knife pictured is W2. My quenchant at the time was McMaster Carr High Speed. I don't care for it. It didn't at the time(and still doesn't) seem like "high speed" quenchant to me. I didn't have the nads or the time to remake the knife if it had problems due to a brine/water quench attempt. When reading the Heat Treat section in Machinerys Handbook I came across the oil over water method and thought I would give it a try to speed things up a bit.

How could a couple inches of McMasterCarr High Speed over water not be faster than just straight McMaster Carr High Speed while still being less severe than straight water/brine :confused:

edited to add : Just to be clear, this is "old news" when it comes to my knifemaking. The experiment was done nearly 2 years ago as was the pictured knife.

Like Ray I tried it and moved on to, IMHO, "better things", namely Parks # 50. Now that stuff is fast and has been everything that I've been looking for in a high speed quenchant :thumbup: :thumbup: :thumbup:


;)
 
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This thread brings up something that has been hovering in my mind. What would happen if you used water soluble oils. Some oils mix with water and don't separate. Our big band saws run an oil/water mix like this on the blades. This type is mixed 1 part oil to 5 water and is very thin, but, I would think it would slow the water a bit and keep it from vaporizing as fast.. I have also seen thicker water soluble oils in the oil field that were used to lubricate and cool big pump rods and liners. These oils were designed to mix with water and cool. Seems like it should work. I am always wondering, what if.
 
ib2v4u said:
This thread brings up something that has been hovering in my mind. What would happen if you used water soluble oils. Some oils mix with water and don't separate. Our big band saws run an oil/water mix like this on the blades. This type is mixed 1 part oil to 5 water and is very thin, but, I would think it would slow the water a bit and keep it from vaporizing as fast.. I have also seen thicker water soluble oils in the oil field that were used to lubricate and cool big pump rods and liners. These oils were designed to mix with water and cool. Seems like it should work. I am always wondering, what if.
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I seem to recall Don Fogg mentioning that he used something along these lines not long ago. This could have also been a dream.

3 things I have thought about using but have never gotten around to trying. Jello, K Y Jelly, and BS. I got one of them bulls, the other's I'd have to go to the store to get. :D
 
I've tried Jello, didn't work so good. KY jelly is a bit pricy for my liking... thinking about trying cactus juice, it's a lot like mucus... snot! LOL :D

I think Mete is correct, fast then slow...
 
What if you as quickly as possible passed the blade through the oil and went to the water and let it sit there for a few sec then retracted the knife up into the oil allowing it to cool slower. or you could quench with the edge down and enter the oil fast and keep going till just the edge is in the water but the spine is still in the water.
 
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