Quenching & cooling methods info?

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I want to learn about methods for cooling, hardening & tempering steel.What I've done in the past is either natural air cooling (room temp) or water quenching (water at room temp).  I know that oil is sometimes used.  20W motor oil is sometimes mentioned.  Are there other oils (types, weights) that are also sometimes useful?And what about good info on Web sites?  Any site(s) worth recommending?I realize my intentions, in terms of uses and projects, are being left vague here.  I want to do some pretty broad learning and then to experiement with a variety of kinds of steel and processes, at home-shop level.  (I'm a carpenter & woodworker who has just started getting his hands dirty with welding & metal in the last year... wish I were living closer to a seasoned blacksmith, and a knife maker too.)Thanks.
Reply:http://www.swordforum.com/forums/found this sight pretty fast, it's a start, do some searches. Bing.com is an excellent search engine
Reply:What kind of steel ?Mild steel cannot be heat treated, though it can be case hardened.Tool steels are available in water hardening, oil hardening, or air hardening.   And even then it is not straightforward because it depends on the size of the piece.Since this is a welding forum, it's worth mentioning that most weld beads can be hardened, whether you want them to or not.   That's why it's better to let a weld cool slowly.I presume you are interested in making carpenter tools like chisels.   That would typically be 0-1 (oil hardening).   Heat to about 1450 F, then quench in oil.    Then it will be hard but also brittle.   To temper the piece, you would reheat it, but only to say 300 - 900 F, depending on what you need.   Tempering makes it tougher, but sacrifies some hardness.
Reply:I have done a bit of Web searching.  (Thanks for the sword-maker's site).When they talk about 'oil cooling', are we always talking, ideally, about 20W motor oil?  Or is some other oil better in some circumstances?
Reply:www.bladeforums.com is another great sight.  Those guys are always on there talking about heat treating steel for blades.  They are a pretty good group of guys too.
Reply:Most of the guys on Bladeforums look down their noses really hard at motor oils for quenching. You need to buy special quenching oils or use olive, peanut or some other natural oil according to them. I only make knifes from old Nicholson and Simonds file and 1095 steel which are simple carbon steels as a hobby. Both respond well to my home mix of 20 wt. motor oil and ATF. If the temperature is right when you quench the blade will get so hard a file won't touch it which is what you want. You can then draw it to the hardness you want depending on your draw temperature. I'm probably doing everything wrong according to the experts. Maybe they are on to something I haven't run across yet. But it works for me. More complicated steels require more sophisticated methods and the equipment can get very expensive. That is why I don't use them.I'm not knocking the information found on that website. I'm a member and very interested in the information found there. Just like this forum, there are some really sharp, pun intended, people there and some that aren't, well, so sharp.Last edited by Oldtimer; 11-07-2009 at 11:26 AM.
Reply:Originally Posted by OldtimerMost of the guys on Bladeforums look down their noses really hard at motor oils for quenching. You need to buy special quenching oils or use olive, peanut or some other natural oil according to them. I only make knifes from old Nicholson and Simonds file and 1095 steel which are simple carbon steels as a hobby. Both respond well to my home mix of 20 wt. motor oil and ATF. If the temperature is right when you quench the blade will get so hard a file won't touch it which is what you want. You can then draw it to the hardness you want depending on your draw temperature. I'm probably doing everything wrong according to the experts. But it works for me. More complicated steels require more sophisticated methods and the equipment can get very expensive.
Reply:Find a class in metallurgy. It will blow your mind!  You will find that every metal alloy has a very specific isothermal transformation diagram that has been researched for you. So if we use O.T.'s 1095 steel, it has a dedicated diagram that will tell you the exact time/temperature change you need to take the metal through to get what you desire from it. The trial and error method also works, and has been the method relied on for millenia. Have fun and keep in touch with the smithies, they can teach you a bunch.Last edited by tanglediver; 11-07-2009 at 11:15 PM.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:Oh, yeah... another question.In the past, I've seen oil quenching from a distance (at the time, unfortunately, I was not interested in metal work - making my living in a different way, and not enough free time).  But I seem to remember that metal that  is quite hot (maybe in the yellow-heat range, definitely hot enough to be red) will cause a momentary small flame to flare in the oil, where the metal is submerged.Do all small-batch quenching oils flare up, to some extent?  Seems to me it could just be in the nature of oils.  Or is this why my web search has turned up the fact that there's such a thing as "quenching oil"?  Is Q.O. resistant to flaming from heat?
Reply:Joel,The hardening and tempering of steel depend on the particular alloy of steel in question.Some steel uses oil to quench, some use water,  some use air.  Quenching an oil-harding steel in water will usually result in the steel cracking.And yes, sticking a piece of HOT steel into oil does cause flames.  Sticking a piece of hot steel into water causes steam, so you have to be careful there too.First, pick or choose what steel you will use.  Then figure out what the heat treatment requirements are.  You may have to pick a different alloy and research again.  The best laid schemes ... Gang oft agley ...
Reply:You should buy this book-http://www.amazon.com/Complete-Moder...7789408&sr=8-5only 14 bucks, its a great, step by step intro to simple blacksmithing, making tools, heat treating, using junkyard tools, and doing it all cheap with stuff you can find easily.No, its not a 5 year swordsmithing apprenticeship.And its not a college degree in metallurgy- but it will get you going, actually making stuff, that works.The author was a woodcarver, who was living in rural Java (Indonesia) before the second world war, and made his own tools using the simplest of procedures.