VEGETABLE OIL QUENCHANTS - Scientific Study - REAL DEAL

JTknives

JTknives

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Jun 11, 2006
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Well as we all know the battle between Vegetable quench oils and Commercial Quench oils has been going on for quite some time. There are Experts on both sides of the line saying what thy know and believe. Mostly on one side you have the vegetable people saying "Hay it works, and works good" then the Real quench people say well "How do you know, where is the lab tests". I really am not on one side or the other, people can use what thy want. I have 5 gal of Parks AAA but thats just because i could not pass it up. Its funny really because all thats need or should i say was needed ;) was a commercial study done on VEGETABLE OIL QUENCHANTS. well i have been searching and searching for a long time for any data related to the quench speeds of different vegetable oils. And if god be willing a comparison between them and a commercially produced quench oil. Well I come to you today to tell you i have found what we have been looking for, for a long time. I hope it clears the air a bit and satisfy both sides of the battle field so we can all be friends once more. Let the revelation Begin.

I am hosting a copy of this on my site so that we will not lose track of it.
http://www.jtcustomknives.com/calendar/files/1/Vegetable Oil Quenchants.pdf
 
very interesting, thanks for posting. i will stick with vegtable oil!
 
Looking at the all important cooling curve, it appears to me that the heat extraction of the vegetable oils are faster than the commercial oils at the very start of the quench (which surprises me), but at the all important nose of the quench (900 f, 480c) the the heat extraction of the commercial oils are higher (even the slow one), and then at the other all important Mf (around 500, it depends) the commercial oils are slower (which is a good thing).

It appears to me that the heat extraction of the vegetable oils makes a nice clean curve, where the commercial oils look to have been tweaked to have a slow initial rate (perhaps to keep things even), a high rate at the nose (which dictates if the quench is successful or not), and a low rate going into martensite formation (to reduce warping). Meaning the commercial oils are better optimized for quenching steel. Which is what they have been saying all along - through chemical magic they've deformed the curve of the quench oils to better match the quench requirements of steel.

It also looks like the over all "speed" of vegetable oils is faster, which I did not expect.

Cool paper. Thanks JT :thumbup:
 
I read the entire article ,word for word, and understood most of what they were saying.

The gist of it was that all the vegetable oils tested were about the same, but were different than the commercial oils. That is what many of us have been saying all along.

The difference shows most clearly in the graph of cooling curves. Notice how the commercial oils drop the temperature fast at the high end, and them slow down as the steel enters the martensitic-start region. This is more desirable than the curve depicted by the vegetable oils. The article even says that the vegetable oils may not be as suitable for higher alloy steels ( which is the class that knife blades are made from) than would be desirable.

Condensed book version of the report, as I read it, is:
Vegetable oils will work, but will oxidize ( go rancid), and display different cooling characteristics than commercial oils.

I see nothing in this report that would make me consider changing quenchants at all.
My vegetable oils will be used for frying eggplant, and my Parks oils will be used for quenching blades.

Stacy
 
bladsmth said:
My vegetable oils will be used for frying eggplant, and my Parks oils will be used for quenching blades.

Stacy
Click to expand...

Oh crap. I've been doing that backwards. That explains the indigestion...
 
Sorry, but this is nothing new. The foreman in our heat treat dept. at work posted this on the board a year or so ago. It basicly proves that commercial oils are better for steel. It does'nt mean veg oil won't work, just not near as well.
 
Interesting!


But doesn't this mean that vegetable oils will make the steel as hard as the commercial oils but with a bigger risk of wrapping?
 
Depends on the steel. If the vegetable oils are slower at the nose of the curve they may fail to fully harden steels that require a very fast quench such as 1095 and W2.
 
Umm, if fastest quench speed was the goal, all the searching and waiting could have been greatly reduced... water and brine beat all quenchants mentioned, hands down. It is when you expand you criteria to multiple other factors that things naturally get more complicated.

I too have seen this study (or one very similar, the text and format seems different), but it fails to alleviate other concerns I have in the consistency of results that I insist on for much of my work. Something that has bothered me concerning this study is the possibility that people could draw conclusions about any petrolium oils other than Micro Temp 157 and Micro Temp 153B, only the most general conclusions can me made about the countless other oils designed for this purpose that were not involved in the test. In quench speed alone there will be a huge discrepency between Parks AAA and Parks #50. How many other liquids could fit between these two oils alone? How many other peterolium based quenchants would fit between them? Based on quench speed alone, AAA is inferior to #50, and both are inferior to water, based on quench speed alone, but is that truly the case?

However this study is fascinating and really shouldn't be dismissed out of hand, there is a load of useful information here about cooling curves and how slight chemical variations, even in natural oils, can have profound effects on properties. Also it is very much worth noting the stability of canola oil in the study while remembering that Houghton has done work with this one vegetable based oil as a quenchant. These studies are invaluable for the little bits of data they provide but even the researchers who do them are often very careful (and wisely so) with their conclusions. The best studies produce more questions than answers.
 
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