Quenchants :

Air, Brine, Water, Oil, Synthetics and
Super Quench

When hardening steel it is "quenched" (cooled) at a rate that causes the proper condition of the steel to be hard. Each type of steel has its own "quenchant" and are often designated by it. Such as O-1 (oil quench), W-1 (water quench) and A-2 (air hardening).

The quenchant is also determined by the size of the part. A huge part that may be made of "oil quench" steel may need to be quenched in a tank of ice filled brine to cool it fast enough. On the other hand many high carbon water quench steels will air harden if thin (such as a blade) OR against the anvil while forging. Remember, its the cooling RATE and that big cold anvil cools the steel quickly.


HARDENING and TEMPERING: . . . never quench anything other than mild steel in COLD water. Warm is best, however every steel has a prefered quenchant. Always test unknown steels in oposite order of severity of quench (ie gentlest quench first).

YES! There are air quench steels. Oil is most common with alloy steels. I almost never use water other than for low carbon or non-hardenable material.

- guru - Saturday, 02/19/00 04:29:31 GMT

Vegatable and Animal Oils These are rarely recommended as quenchants any more due to going rancid. Mineral oil is cleaner and doesn't become rancid. More blacksmithing supplies from Johnson & Johnson (baby oil).

Mineral oil is used in bulk (55 gallon drums) by bakeries and other food processors. You can also purchase it in small quantities as noted above as "baby oil". The difference being that the baby oil may be lightly perfumed.

- guru -Tuesday, 04/24/01 18:09:27 GMT

MORE on QUENCHANTS:
Steels haven't changed much since the 1970's. There were BIG changes from the early 1940's. However, most rules are pretty much the same.

Old recipes for quenching oil are often in the category I call alchemy, some witch's brew. No science, mostly old wives tales or whatever was on hand. Certain oils have been found to be better than others. Mineral oil works well, so does ATF. Synthetic oils with no or very high flash points are very good. The old non-inflamable PCB transformer oil would make GREAT quenchant and is a good reason NOT to bring home someone's old tank of quenching oil. Modern industry use polymer quenchants which can be adjusted to the needed quench rate.

Thickness of the section does make a difference in quenchants and technique however the definition "heavy sections" are big dies and anvil size pieces of steel. In those cases many steels are listed as oil OR water hardening and that means water for "heavy" sections. Some steels just cannot take the thermal shock and you use the recomended quenchant only.

- guru - Monday, 02/21/00 17:59:11 GMT

How do you Oil Quench something without having the oil flame into your face. I just cleaned up after the last attempt that burnt out the bucket. I use about a gallon give or take.. Is that enough??

Sparrowhawk - Saturday, 02/19/00 17:24:55 GMT

Sparrow depends on the size piece you are quenching. If you are heat treating a few watch springs 1 gallon of oil is plenty. If you doing larger items in larger numbers use more oil and keep it agitated or stirred. Keep the oil below the flash point. It takes more oil to heat up to the flash point then it does less. Always have the oil in a noncombustible bucket with a noncombustible lid. If the oil flashes and catches fire cover the bucket with a lid. Never use water to put out a flammable liquid fire. Always have a working class B flammable liquids fire extinguisher close by if a fire gets out of control. Big fires start small.

Bruce R.Wallace - Saturday, 02/19/00 23:42:57 GMT

OIL QUENCH: Think about it, oil is less dense than water, less thermal mass for the same volume. It is not as good a conductor of heat as water so the heat is going to build up around the part raising the temperature of the quenchant even higher. It does not evaporate therefore cooling itself like water (it does, except that white 'smoke' is very near the flash point - something you do not want).

Commercial oil quenching tanks have water cooled heat exchanges to keep the oil temperature under control. High flashpoint oils are better than low. Many synthetic oils are non-flamable and make GREAT quenchants for the small shop.

Bruce is a former fireman, and knows what he is talking about when it comes to fires. Oil quenching is something we often get into to unprepared. It is a LOT different than using water. As mentioned the container must be steel and there must be a steel lid. Preferably the lid is hinged to the container so that it is not missing when you need it. You need a large well ventilated area preferably with an exhaust hood. Most oil quench tanks have a rack or heavy screen basket so that you can drop the part in and not have your face or arms over the container during the quench. For small parts like a knife 5 gallons is a good starting point. More is better and it is a good idea to have a cooking thermometer in the oil if you are doing multiple quenches. You may have enough oil for one or two parts and the third one may flash if the oil temperature has risen enough. - guru - Sunday, 02/20/00 01:51:21 GMT


SAFETY NOTE:

NEVER, use a plastic container for oil quenching. If the oil catches fire the plastic will follow and dump flaming oil and plastic everywhere! As Bruce is fond of saying, big fires start small. Plastic containers such as the ubiquitous sheet-rock mod buckets are not even suitable for water quenching as the steel can still melt through the bottom while being quenched.

Quenching in oil: I tell my people that I use quenching oil, and I usually get a vacuous stare. A few years back, I went to my Texaco distributor, not a filling station, and bought a 55 gallon drum of "quenching oil". It had the trade name of Quenchtex. I think they had at the time, a rapid grade and a slightly slower grade ("A" and "B"?). Back then, I was doing lots of O1 tools. I got the "slow acting", but it's fast enough. The oil has a higher flash and burnoff point than some of the other stuff mentioned, and it has the proper rate of heat abstraction. And warmed up oil quenches a little faster than room temperature oil, because of the change in viscosity. A safety tip that seems to work for me: I try to submerge the whole tool quickly, at least what is red hot. It seems that if you leave a little red heat above the oil level, it wants to flare up.

Frank Turley - Friday, 03/29/02 01:19:27 GMT

Now, in the "old days" (1950s, early '60s) you could still get whale oil for a quenchant! I remember an article playing on the continuous mystique of the quenchant (since at least Roman times all sorts of virtues imparted to the steel were attributed to the quenchant) saying that since whaling and whale products was being banned in the U.S. there would be no more whale oil for traditional blacksmiths to "properly" temper tools.

I keep a small container of bacon grease at the forge for when I'm working small chisels and punches. After heating with a propane torch I quench them in the grease. Ummmmm! Smells like breakfast!

Visit your National Parks: www.nps.gov

Go viking: www.wam.umd.edu/~eowyn/Longship/

Bruce Blackistone (Atli) - Friday, 03/29/02 03:00:36 GMT

PEANUT & INHIBITING OXIDATION (GOING RANCID)

Peanut oil has the highest flash point of all the edible oils. That means that it will get to a higher temperature before it starts to smoke. Chinese chefs use it to the exclusion of all other oil. Stir frying should be done at a very high temperature. One trick that chefs use to extend the life of their deep frying oil is to add vitamin E to the oil. Don't laugh too quickly, there is a reason why. It delays the oil going rancid,(oxidising) thus extending its working life. .

Vitamin E is an anti-oxident. Antioxident chemicals inhibit oxidation by mopping up free oxygen free radicals in the oil solution. (vitamin C does the same thing but itis not oil soluble, so it won't work).

Costco is a good sourse of cheaper vitamin E. The gel capsules should be opened and the fluid added to the peanutoil. Dispose of the empty gel caps.

Please keep a lid on the oil quenching container to keep out all kinds of floating crud and also animals that could drown in the oil (& make a really smelly mess).Light also speeds up some oxidation reactions, so keep a lid on the container when not in use. A locking device will keep the raccoons away, hopefully.

I am not sure how much vitamin E should be used, per gallon of peanut oil quenching. Experiment and let, all of, us know how much is effective Support the site, join C.S.I.!!! Regards To All,

slag - Friday, 03/29/02 03:41:59 GMT

RE quench oil. It is true that old deep-fry oil ( usually peanut oil) will go rancid after a while. There are 2 solutions to this problem.

1...ignore it till the smell goes away in a month or so and it wont bother you again ( not sure if this is cause the smell is gone or because it has overwhelmed my ofactory sensibilities)......or

2..When it ceases to make your shop smell like a cheap deep-fry joint, pour it back in the container and go back to the back of the deep fry and trade it in...might skip the fish fry places, unless you like that sort of thing especially...fish don't generally age well.

Please heed Mr Sundstrom's hard won experience regarding the special aesthetics of quenching in drain oil. I've used drain oil and worse (PCB transformer oil was touted as "inert" with a high flash point and I used it for years. They were right about the high flash point.) So when the excellent Mr Kidwell pointed out the virtues of used fry oil, I was mighty pleased.

LOL...hurray Slag I like the vitamin E solution!

Pete F - Friday, 03/29/02 08:20:49 GMT

OIL QUENCHANTS: May I insert two bits of unsolicited input? I use cheap (hot press) olive oil, from costco in 2 litre jugs, and I keep it in an old aluminum coffee maker (holds about 3 ltrs), then if I want, I can easily warm the oil, or leave it cold - very handy for me, especially as the oil gets sorta thick in the winter if left unheated. May not smell as good as peanut oil, but a definate improvement on used motor oil (gag)...Tim

Tim - Wednesday, 04/25/01 15:17:14 GMT

SUPER QUENCH


Super Quench was invented by Rob Gunter of Los Alamos Laboratory after they banned the use of sodium hydroxide as a quenchant.
ROB GUNTER'S SOAP QUENCH
  • 4 1/2 gallons water
  • 5 lb. salt
  • 32 oz. Dawn dish soap (blue)
  • 8 oz. Shaklee Basic I

    Stir before each use

  • Now, what is it? Basically it's a heave brine solution, with a surficant and an anti-bubbler in it.

    It will not turn mild steel into tool steel. But for those applications where we need mild steel to be just a little bit harder, it does a good job.

    One test took a piece of 1" steel bar, (1018 if I remember correctly) heated one end to non-magnetic and quenched it in cold water. The other end was also heated to non-magnetic and quenched in Super Quench.

    The cold water end tested at about 18 on the Rockwell C scale, and the Super Quench end tested at about 42 on the Rockwell C scale. That's an appreciable difference.

    I use it on RR spike knives. The regular spikes won't really take or hold an edge. (although I've been told that the ones marked HC will, I've never had any of them) but when quenched in SQ, they do take an edge and hold it fairly well.

    OH! BTW, Shaklee is a line of bio-degradable detergents. Basic I is the basic industrial strength formula. Shaklee distributors are listed in the yellow pages of the phone book.

    As for Case Hardening, Kasenit, (sold by McMaster & Carr) does a good job.

    Paw Paw Wilson - Saturday, 05/19/01 21:33:46 GMT

    Super Quench: Paw-Paw is a great believer in super quench. I am not. You can get the same results using ice water and quenching hotter than normal. The hardness achieved is untempered hardness. The result is brittle steel that when tempered is considerably softer. If you need hard, use real steel. Old tools and springs to recycle are too easy to come by. Be VERY careful not to use superquench on high carbon or alloy steels.

    In 1885 steels were brine and water quenched. I don't think I EVERY got into a hardening tempering discussion doing a public demontration. The only time it came up was when very missinformed character tried to tell me how to do it. In these cases in public all you can do is keep working and hope the idiot goes away. Otherwise you make him look like an idiot in front of family and friends. Its not good to argue with the the public. .

    - guru - Saturday, 05/19/01 23:29:01 GMT


    In my net surfing, I came across a formula for a soap quench, but it calls for 8 oz Shaklee Basic "i" (a wetting agent. I have no idea what this stuff is (or what a wetting agent is for that matter). Can you please help me?

    the formula is:

    5 Gal water
    5 Lbs table salt
    32 oz dawn dishwashing liquid (the blue stuff)
    8 oz Shaklee Basic "I" (a wetting agent)

    minatawa - Monday, 02/21/00 14:37:25 GMT

    Minatawa, What you have found is Super Quench. It is often used on mild steel to get a little extra hardness. I've found that COLD (ice) water does the same thing. You don't want to use it on high carbon steels. Its a kind of alchemy but a lot of folks believe in it.

    -guru - Monday, 02/21/00 14:47:49 GMT


    Guess it's time to tell one on myself.

    I had some punches that a friend had given me. Mystery metal as far as I knew. I made a reversed "TUIT" punch so I could make round tuits. (grin)

    When I finished making the punch, I heated it to non-magnetic, quenched it in Super Quench. The punch SCREAMED when it went into the quench. Didn't hiss/steam, it SCREAMED.

    Second time I hit it with a hammer, it shattered into a dozen pieces.

    Turns out it was S7 tool steel! (grin) Taught ME a lesson. Super Quench is for MILD steel ONLY! (grin)

    Paw Paw Wilson Monday, 02/26/01 20:14:50 GMT


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