Eye opening quench test results.

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Kevin R. Cashen, Sep 23, 2010.

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  1. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    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.


    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 all the homemade and improvised quenchants some folks feel work “just fine”, and I hope it gives pause to those of who feel carefully formulated quenchants are unnecessary.
    Last edited: Sep 23, 2010
  2. fitzo

    fitzo Basic Member Basic Member

    Aug 14, 2001
    Excellent demonstration, Kevin!

    I picked a great time for one of my rare visits to the forum. Thanks for the timing. :)
  3. Burton Harruff

    Burton Harruff

    Oct 1, 2007
    Interesting, keep us posted as further developments occur.
  4. deker


    Nov 14, 2005
    I had the good fortune of catching Kevin while he was going over these results with somebody at Ashokan and got to see the test coupons themselves. It was shocking to me how similar these two samples looked to the naked eye in comparison with what the micrography showed.

    I'd like to personally thank you Kevin for all of your hard work in what is very often a thankless task. We're listening, we're learning, we're questioning, and we do appreciate your efforts. Please keep us posted on how this project goes. I for one would love to have a readily accessible fast oil. I mean, I'm stocked with Parks #50 right now, but students and friends of mine are having a rough time of it.

  5. 12345678910


    Jul 13, 2009
    I love that measurable analytical approach.

    Is the control oil new and unused, like the test oil is ?
  6. Mitchell Knives

    Mitchell Knives Knifemaker Moderator

    May 21, 2000
    Very informative post; makes me glad that I spent the extra $ for a professional quenching oil.
  7. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    Interesting question, since the speed of aging oil is not always slower. Yes both samples where fresh and ready for the test.
  8. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    I have put the Parks bug in enough peoples head that I feel somewhat obligated to help in moving the industry forward in providing more equivalents. But in the meantime I feel it right to share the lessons I myself am learning about the intricacies of properly quenching steel. Many are very happy with "good enough" and what they are currently using, but when you can clearly see how much of a gain you can get I am sure there are many who will want to go for it.
  9. tiguy7

    tiguy7 Gold Member Gold Member

    Jun 25, 2008
    Jeesh, and I thought that one could make a great blade using a horseshoe and motor oil.
  10. LRB


    Feb 28, 2006
    Keep at it Kev. We need oils that are easy to get, and work right. Thankyou for your time and research in this area.
  11. Robert Mayo

    Robert Mayo

    Oct 13, 2005
    Thanks for posting this Kevin.

  12. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    I heard that a good smith could lick the steel and tell how much martensite there was by the taste.:D The "Scratch it with your fingernail" test is ,however, unreliable.:mad:

    Great post Kevin, Thanks.:thumbup::thumbup:
  13. gga357

    gga357 Gold Member Gold Member

    Dec 3, 2007
    Kevin, I have learned quite a bit from your post. Thanks.
  14. Rick Marchand

    Rick Marchand Donkey on the Edge Moderator

    Jan 6, 2005
    Kevin is the type of guy who shines one of those CSI blacklights in every hotel room he spends the night in. I bet that sometimes, he wished he didn't know about the blood and semen and just got a good night sleep.

    All joking aside... your blood sweat and tears are not going to waste. We all appreciate the way you freely share your findings with us. You are a beacon of light in the smoking quench tank of purple panther piss and peanut oil. Okay, I really can't help but joke around, sorry.

    Great stuff Kevin..... please tell me Houghton K is one of the good oils?... that's all I got, man.

  15. David Sharp

    David Sharp

    May 23, 2008
    Thank you very much for the continuing education.
  16. Darrin Sanders

    Darrin Sanders Knifemaker Moderator

    May 6, 2009
    Thanks for sharing the results of the test Kevin. I have gained lots of useful info on H/T'ing from your threads. I've heard you're writing a book on the subject. Any truth to this?
  17. Bigfattyt


    Jun 23, 2007
    What? Does this mean I need to toss out my knife I made in the garage? 5160 heat treated in a hibachi grill and magnet, and quenched in used motorcycle oil (synthetic racing oil).

    Then tempered in my super accurate 20 year old oven!

    Great post. Looks like I know who I am sending my next knife to for the heat treat! (It is about 19 inches over all, so I am not going to try and heat treat it "shade tree" style).
  18. sharpeknives


    Jan 13, 2006
    Kevin, Thank-you for this post. You have proved what I keep preaching. Your work and time posting are greatly appreciated.
  19. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    Actually that has been true for around 5 years now, but now fate and forces beyond my power to oppose are bringing it to fruition whether my procrastinating self likes it or not (in other words my wife will simply slip a knife between my ribs if I put it off any longer;))
  20. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    Martensite is more tinny flavor, while pearlite tastes more chalky:barf: I tried to taste austenite once in 1095 but only picked up the flavor of scorched tongue:( too bad it would have been handy to determine how much retained austenite many tool steels could have. One can try stainless but the peppery bite of chromium totally overpowers it.
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