Eye opening quench test results.

Kevin R. Cashen

Super Moderator
Although I am very careful to protect the privacy of my clients for whom I do consulting and testing, this research has so much educational value that I asked for permission to share some of the results with my knifemaking friends. I am currently involved in a project to help a quenchant manufacturer (not Parks or Houghton) develop some oils to specifically meet the demands of certain steels. The first goal is a very fast oil that will work for shallow hardening steels, so I am testing with a fast oil control.

Below you will see results from one of the first prototype formulations, starting at lower speeds, on 1095. 1095 is one of the toughest to thoroughly harden so I thought it would be a good challenge. The samples where ground from the same bar of steel, austenitized side by side with direct thermocouple monitoring in salts, and quenched side by side in identical quantities of oils and agitation, surrounded by a 125F bath to assure temperature. The results were then cross sectioned and roughly polished for metallographic examination (so please overlook the scratches). Micrographs were actually taken at 1mm increments from the edge but I only took a sampling to put this image on the web. After this the samples were then tested for Rockwell hardness at roughly 3mm increments.

oiltest.jpg


The light background is martensite (the good hard stuff we want), the dark stuff, making it look like blue cheese, is fine pearlite (the soft stuff that quenching is supposed to avoid). Please be aware that at the edge both of these samples would have skated a file just fine, would have flexed over a brass rod all you want, and would even have cut a few 2x4” with little problem. But every little black patch represents a percentage of overall loss in strength, and long term edge retention.

Do be aware that that prototype oil would probably have held its own against many medium speed oils and was made by guys who’s business it is to make oils specifically for quenching and know what they are doing. This was a good oil but was still a first step in moving from medium to the fast speed, with a few adjustments that were yet needed to reach the goal, and many more tests in that process. But the speed factor is just one area among many to account for, long term stability, vapor points, interaction with the surface finish etc…

The real point of this post is that making a real quench oil isn’t all that simple and testing it is even less so, believe it or not these are just rough preliminary tests and not all that exhaustive. I hope this gives somewhat of an insight as to my perspective when I express my doubts about some of the homemade and improvised quenchants some folks feel work “just fine”, and I hope it gives food for thought to those who feel carefully considered quenchants are unnecessary.
 
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Thats pretty interesting. I'm a newb at this
Question : What is the best "fast" oil currently on the market for 1095 ?
 
Kevin,

You've got my full attention.....so spill your guts, I know more folks than just me want to know what your "control" quenchant is. :) I do have to ask the question, was there a specific reason that 1095 was chosen as the test steel?

I'll keep watching! Many thanks for taking the time to share!
 
That has got to be the best explanation for using the proper quenchant I have ever seen or heard.

Thanks for sharing,
Carey
 
In time I will be able to reveal much more, but in the meantime the information and results are really not mine to give. I chose 1095 because it is the toughest to fully harden steel commonly used by knifemakers, nail a good curve with that steel and any shallow hardening alloy should fall into line quite well. Just remember that while Parks #50 is indeed a very good fast quench oil, it is not at all the only one out there. I would love to be able to do all sorts of these types of tests but I would also love to make all kinds of blades just for me to have for myself, and for the same reasons I cannot do either. But when you are doing it for a client suddenly the time is not just time loss to the business end of things. But the specifics of what I am trying to do with this client is separate from the striking lesson of how much a difference very small changes in the quenchant can make. Knifemakers will use many substances that had no quenching considerations in their creation, and be quite content with the results, for some time I have been painfully aware of what even the subtle differences in carefully formulated quenchants can make, my hopes were to give a little insight into why I am such a neurotic bug about it.:3:
 
Thats pretty interesting. I'm a newb at this
Question : What is the best "fast" oil currently on the market for 1095 ?

Any oil with a rating faster than 9 seconds should get you in the ballpark. Many would recommend Park Metallurgical #50, which is indeed fast enough but is also very hard to obtain or even more expensive. I would recommend a few of the oils offered by Houghton International, like type "K" or Houghto-Quench 3440 which may be about the fastest out there. Parks #50 has become all the rage, and I share a large part of the guilt for that, but Houghton is the largest, oldest and more friendly to deal with, so I cannot recommend their products enough.
 
Kevin,
Just forgiggles and cause your da man


what is the recommended quench temp for oils like houghton and parks 50??
 
Most oils work best in a range from 100F to 150F, above that is bad. Some very fast oils such as the #50 can work from room temp on up to 130F but should not be allowed to go hotter. I do not have the exact numbers for the Houghton stuff right in front of me but the range is still valid. The medium speed oils are not as touchy, they have higher vapor points and so can handle the higher end of the same range.
 
Thanks Kevin.
Houghtons website says min temp of 70f to a max of 200f , with a recommended temp of 140 - 160f

Holly Hell , $250 for 5 gal.............I guess it would last quite a while though.
 
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I also contacted a local sales rep. for Houghton to get a price on there K quench it was 175.00 + shipping ....steve
 
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Thanks Kevin the pictures realy helped me to understand more of what i have been reading.
Thanks and God Bless
Rodney
 
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