Tim McCoy Posted January 18, 2012 Share Posted January 18, 2012 Would some of you with more technical knowledge share with the rest of us the differences in "Super Quench", Water and Oil as quenching mediums? What is best for what? Is there a quenching medium that is sufficient for "general" work ... or do we really benefit from specialty formulas? Gotta favorite recipe? Thanks ahead of time for your input. Quote Link to comment Share on other sites More sharing options...
BlissStreet Posted January 18, 2012 Share Posted January 18, 2012 If I understood this properly, the super quench was developed to harden medium carbon steels. The various ingredients lower the surface tension of the water and degrade bubble formation, allowing greater contact with the steel. The story behind it is quite interesting. And if you need it, then yes, you benefit from it. But it's not a daily use item for most I would think. Others, like simple brine, are ages old. From what I have seen, both here and in other research, is that oil and water are the two everyone seems to keep on hand. Quote Link to comment Share on other sites More sharing options...
Frank Turley Posted January 18, 2012 Share Posted January 18, 2012 My search engine found www.navaching.com/forge/quenchants.html. To simplify a bit, in my own experience in a small shop situation, in the order of speed of heat abstraction, brine (salt water) is the fastest quench. I hardly ever use it, because it's not always called for by the metallurgists' specs. Brine is fast, because the vapor formed around the submerged piece is got rid of right away. The brine causes the scale to be thrown off thereby allowing the liquid to contact virgin metal. Water is next fastest and is a fair quench for water hardening steels that have some mass. The work is agitated in the water to shake off the vapor blanket; I often figure-eight the piece under water. HOWEVER, thin sections of water hardening steel get an oil quench, because the vapor blanket stage is slightly prolonged with oil when compared to water. The oil, therefore, is slower and less harsh in its action, and this helps to prevent warpage and cracks on thin pieces like knives. I use Quenchtex, but if a proprietary quenching oil is not available, I have used non-detergent motor oil...NOT dirty crankcase oil. Keep it clean. Warm oil quenches faster than room temperature oil, because the viscosity changes. If oil is not available, luke warm water may help slow the quench, when desired. I have talked to Robb Gunter about Super Quench. When he worked at Sandia Labs in Albuquerque, he would quench low carbon steels in lye water, sometimes called caustic soda or sodium hydroxide. This acted as a super quench. When the Inspector General came around, Gunter was informed that the lye would have to go. It was considered too caustic to be in the building. Gunter, being a metallurgist and knowing something about chemistry, came up with the Super Quench formula, which wasn't so caustic, and which satisfied the Powers that Be. Personally, I have never used it. I buy tool steel that I know will harden in the proper quenchant. Quote Link to comment Share on other sites More sharing options...
MattBower Posted January 18, 2012 Share Posted January 18, 2012 Frank has it, but I'll expand a little on what he said. Order of speed of quench, from fastest to slowest, goes something like Super Quench--brine--water--oil. The speed of water varies inversely with temperature; hotter water is a slower quench compared to colder. Speed of oil varies directly with temperature, up to a point: hotter oil is a faster quench, compared to the same oil at a lower temperature. But beyond a certain point, heating oil slows it down. That point is going to vary depending on the particular oil, but it's likely to be somewhere north of 150 degrees F or so. The speed of an oil quench also depends on a host of other factors, with one important one being viscosity. Generally speaking, lower viscosity oils make faster quenchants than higher viscosity oils. Oils can provide a huge range of quench speeds. As for a general shop quenchant, it depends what sort of work you're doing. If you're only working with 10xx steels in relatively thin cross-sections, you can probably get by with clean water (distilled is good) and a fast oil. (Warm canola is pretty fast, and has a fairly nice cooling curve. But a good quality commercial quenching oil won't go rancid like canola, and will last much longer in use.) If you add a variety of tool steels into the mix, all bets are off. And if you want to be able to significantly harden mild steel, you're going to need some Super Quench as well. (However, just about any tool that you could make from mild steel hardened in Super Quench, you could make better with a properly hardened and tempered medium or high carbon steel. Good steels aren't hard to come by.) Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 18, 2012 Share Posted January 18, 2012 All y'all keep forgetting *air*, the slowest and gentlest quenchant. Usually only hardens air hardening alloys and normalizes the rest. However in thin section many alloys will harden well "one step gentler". So a knife blade made of a water hardening alloy might do better in oil and an oil hardening alloy may even harden in air! As they may crack in their "proper" quenchant it is often a good idea to try the gentler one first! If it doesn't harden appropriately then you can repeat with the harsher quenchant. Quote Link to comment Share on other sites More sharing options...
pkrankow Posted January 18, 2012 Share Posted January 18, 2012 You forgot air Super Quench-->brine-->water-->oil-->air Very good information contained in this thread. Now, something to also consider is quenching can be done with a solid material too, such as pressing between plates, or against the anvil, or clamping in the vise. This means that if you are forging a tool, and need to do an upset, or hot filing, or whatever clamping the part in the vise MAY cause localized hardening of the metal, and if this is not corrected in the next step (reheating) it may cause a brittle spot. Phil Quote Link to comment Share on other sites More sharing options...
trying-it Posted January 18, 2012 Share Posted January 18, 2012 Some folks use old used oils such as motor oil, vegetable oils, peanut oil,etc. Used motor oil has its own related issues as toxic fumes may given off with any form of heating. Also beware and remember that there are people that can have severe allergic reactions from coming in any contact with peanut oil. A piece quenched in peanut oil now and later handled by a person with such an allergy can trigger a violent allergic reaction, some as severe as being fatal. Play it safe, don't tempt fate! Just my $0.02 Quote Link to comment Share on other sites More sharing options...
MattBower Posted January 18, 2012 Share Posted January 18, 2012 I didn't forget air, I just didn't include it because it's generally only relevant to deep hardening tool steels. (The OP's question is implicitly about quenchants for hardening.) If we want to exhaust all the options, we should also be talking about molten salts -- they're not just for austenitizing, you know! -- polymer quenchants, high pressure gases like pure nitrogen, and all sorts of fancy stuff that has no bearing on general shop use. (I actually deleted several paragraphs from my first post when I realized I was going way beyond what he asked.) On the plate quench, I'll mention that I managed to quench crack a piece of O1 this past weekend by working a thin section on a cold anvil, then letting it cool to ambient. The next piece got slow cooled on the coal/coke pile next to the fire, and then tempered by sitting on top of the fire for a while. Quote Link to comment Share on other sites More sharing options...
jimmy seale Posted January 18, 2012 Share Posted January 18, 2012 just to throw my .02 in..i use non-foaming hydrlic oil...heated to about 120/140 degrees, i believe in it's cool state it is a 20 vis.and it has a high temp rating but still flairs.as for H2O everyday water is 8.34 ppg and saturated brine is at 14 ppg. please don't play with sodium hydroxide! PH on that stuff is nasty..in oilfield terms it will eat your --- up. for reference take a 30 gallon tub of 90 degree water..add in a sack(50#) of caustic and ph will be 14 and that 90 degree water will go up to 180 degrees...the chemical burns are nasty, be careful and choose wisely, jimmy Quote Link to comment Share on other sites More sharing options...
Tim McCoy Posted January 19, 2012 Author Share Posted January 19, 2012 Wow !! Great information and really appreciated. Good to have all this on one spot to refer to. Frank T. thanks for the link . . . Tim Quote Link to comment Share on other sites More sharing options...
dkunkler Posted January 19, 2012 Share Posted January 19, 2012 Frank has it, but I'll expand a little on what he said. Order of speed of quench, from slowest to fastest, goes something like Super Quench--brine--water--oil. Don't you mean fastest to slowest? Quote Link to comment Share on other sites More sharing options...
MattBower Posted January 19, 2012 Share Posted January 19, 2012 Don't you mean fastest to slowest? I sure do! Dang. Getting old(er) sucks. I'll fix that. Quote Link to comment Share on other sites More sharing options...
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