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  #21  
Old 12-22-2007, 11:51 PM
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weldor2005 weldor2005 is offline
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Default oil

in my metallurgy class we used hydraulic oil to quench any of our oil hardening materials. If you got s1 instead though, i'm not sure that i would be making chisels out of it, however it would work, but not most suited for the job at hand.
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  #22  
Old 12-23-2007, 09:40 AM
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Barry's advice is solid. The important thing is whatever is used (oil) has a high flash point. I don't think the type of oil is important other than I would steer away from HD oils. Don't know what affect the detergents have on the metal. I have always used 30Wt non-detergent.

Basically the oil is simply a medium by which the temp of the metal is rapidly reduced.

I defer to the wisdom of someone more experienced like Iforgeiron...
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  #23  
Old 12-23-2007, 06:16 PM
R Funk R Funk is offline
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Default Quench Mediums

One of the things I keep in mind that in general there is no secret in the quench media. The variable that is important is cooling rate and uniformity of quench.

We want to quench as slow as possible and still get get the untempered hardness needed for the application. Too fast quenching cause residual stress which weakens the object and can cause cracking

Rates of quench From fastest to slowest
(remember that agitation increases cooling rate)

Brine
Water
Oil
Air

Brine is more uniform quench than water as water forms a skin of steam around the item being quenched. Sometimes things that crack in water may not crack quenched in brine due to increased uniformity of quench.

The other factor is the size of the item. A larger item takes longer to quench and remember that variable is cooling rate.

A stress relief before hardening may also reduce quenching.
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  #24  
Old 12-23-2007, 06:23 PM
R Funk R Funk is offline
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Default CORRECTION Sorry

A stress relief before hardening may also reduce ***cracking and internal stress***

Sorry!
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  #25  
Old 12-23-2007, 07:00 PM
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R Funk, well said. Although there are no real secrets, there are techniques and quenching media that are more suited to one job than another. As you point out, brine, though perhaps a more drastic quenching medium, does apparently reduce the chances of cracking on an object of more complex shape.

Incidentally, quenching oils do vary widely in their rate of cooling from what I've read.
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  #26  
Old 02-16-2008, 11:48 PM
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Jake the Mad Russian Jake the Mad Russian is offline
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Quote:
Originally Posted by ace4059 View Post
I have a question: It maybe stupid but what oil do you guys use.
The reason I ask is because it seems to me, some oils would burst into flames if you placed red hot metal in them.

-Ryan
Ryan-there is such a thing as a legit quenching oil,it's very expensive,and only the very finest anal-retentive metallurgy warrants it's use,maybe some milling cutters or such.What matters in any quenching medium is it's boiling point,and that does not differ greatly between brand-name quench oil,waste oil or lamb's fat.Don't worry about it flaming up-it will go out again,flames do no harm,you're not holding the metal in your bare hand,anyway.Any place where you'd be likely to frolick in like matter should take it without a problem,if it won't-get the combustibles the heck away out of the forge,they've no business there.While quenching it's CRUCIAL that you move the metal around in such a way as to prevent the gases forming around it-their temp.is way different and negates the whole process.(with water especially-steam insulates and transfers energy very poorly).The lid on the oil quench,thusly,is impractical,though sounds nice.Had to put in my 2 cents worth to uphold the hohor of the backyard abortionists everywhere,after all,all of the discussion above was carried on without any idea of what sort of steel was in question.Safety first!I never use anything but waste oil,on principle.
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