I've always quenched in automatic transmission fluid. In the interest of consistency and quality, I'm going to make the switch to a sure-fire quenching oil like Parks or Brownells. I'd also be willing to use mineral oil if I could find it. I thought that first I'd see if some of ya'll would post what you are using, a supply source for it, and most importantly why you use it. ATF has worked pretty well for me so far (about 6 years), and I'm a bit nervous about switching to something new, but I know that there are other quenchants out there that work at least as well, and maybe some that work a little better. I don't want to go to something that's too fast, or something that's too slow. I forge with mostly 5160, O1 and 1084. I'm going to be trying out some 52100, W2, and 1095 in the near future. I make my own damascus out of 1084/15n20. Any feedback on quenches would be most appreciated. Thanks!
Redneckswami, I apologize, I can see that I went right into a speech without really addressing your questions, I have been doing this topic for so long that I tend to anticipate the typical direction it goes and get ahead of myself.
I use the quench oils I do for so many reasons I could burn up a whole lot of bandwidth listing them. You have a really wide range of steel listed and you need to break them down into two categories in order to assess your quenchant needs. 5160, O1 and 52100 are deep hardening ad will handle a slower oil better and fast oils could be stressful for them. 1084, 1095, 15n20 and W2 are all shallow hardening and need a faster oil to fully harden. You would actually be doing yourself a favor by steeling on two or three of these steels and becoming as familiar as possible with them, it that “jack of all trades- master of none” sort of thing.
A properly formulated quenchant will produce much less vapor, thus decreasing the likelihood of flashing, but more importantly it will allow more liquid to contact the steel and pull heat away evenly. It will be designed to stand up to 1500F steel being added to it again and again without breaking down, and it will not pit or discolor the surfaces nearly as bad. It will cool very quickly through the critical stage of pearlite formation and cool slower through the stressful later stage of hardening, basically it was meant specifically for the task at hand.
Kevin, I got the Parks because you and the reading I have done at your direction have convinced me of the importance of a proper HT. The whole cycle is critical. I spent the money on parks because it is closer to sure fired than ATF. I just have to be curious as to the results from the ATF. What was I making in the past? How hard does it get 1095 or W1. How does it look under a microscope? I really hope I can score the Rockwell tester at a reasonable price. I now have some D2 and basically all I can do is follow as closely as possible to the information and advice of those I believe in. I can do the rod test, cutting test etc. But I really don't know. I have decided to go with a good oven with a pid and top quenchants or methods.
On you one comment of industry and lives and fortunes. I use a punch press quite often at work. The punches are a mass produce item and when you think of the stress and watch the machine when it does something like punch a 13/16" hole thru a piece of 3/4" of 304 ss you have to appreciate what they do. I had a slot punch become misaligned once and a very small shard (a bit more than a bb if it would have been round) hit me in the jaw. It went thru my cheek upwards into my gum. It hit so hard it was like a a super hard punch. I was completely dazed and I thought I had must have lost a tooth and be all torn up. In the mirror just a small entrance hole and was able to pull the piece from my gum. The thought of a whole punch breaking off and flying around is horrifying.
I can see where you would have an appreciation for the care that industry has to take with getting things just right. Of course the most common bladesmiths answer to your punch dilemma is to make the punch so soft that it will just bend or flatten out instead of breaking; there would be very few holes made in anymore 304 stock, but that was only a secondary concern for a good punch anyhow. A good punch would bend back and forth endless times without breaking!
I can’t believe the number of knifemakers that cannot see the naivety of thinking they are pushing the envelope on steel treating in ways that industry has never dreamed of when you realize the stakes of not getting it right on a run of simple punches versus one knife that made 20 more cuts on a rope!!!
Let’s see, the metal in a jets landing gear, or your 4 inch drop point- which has more riding on the heat treatment??
With some steels you may find very little pearlite left after a dunk in ATF, others…well. But then even if you get 100% out of the steel you still have to look at all the other benefits in convenience and consistency. I used to play with different home made mixes for certain hamon effects in my blades but I was always struggling with getting it to come out the same as that one I liked. Then I switched to Heat Baths stuff and even if I take it from a different barrel two years later it seems to be the same high quality, but then If you think about it if the guys who make those punches suddenly had a few thousand come out wrong after using the newest batch of quenchant, that quenchant company is not going to be in business very long. The knifemaker dipping hot blades in bacon fat is not held to anywhere near that level of competency.
Kevin have you or anyone else noticed less warpage due to using a proper quenching oil versus using veg or mineral oil? You are able to eliminate the factor of uneven heat with the salt pots, so it would be interesting to know, I would imagine the more even cooling of an oil designed to cool things off would be more even than an oil like veg or peanut oil designed to abosrb and hold heat for cooking.
Sam, the answer to your question is
yes! If heating is consistent there are two main areas where distortion can occur (main areas – the minor areas are infinite, it would appear
) On a shift from bcc to fcc and the shift back. On heating there will be expansion until austenite forms then there will be a drastic contraction until the conversion is complete, many of the recommended lower presoaks are for dealing with this issue, in order to allow the heat to equalize before passing through this dimensional change as evenly as possible. The next problem area is on the way down. Assuming you have not made any pearlite there will be contraction until around 450F, then martensite formation will cause huge expansion, if it doesn’t occur evenly there will be distortion (once again of you doubt this just watch what happens to a straight katana when the edge reaches 450F). Quench oils are designed to keep vapor jackets to a minimum, providing more even cooling. They are also designed to cool more slowly from 400F downward.
)
