Specific Gravities and Viscosity

G

ghost squire

Joined
Feb 1, 2004
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Of many oils at different temperatures including typical quenching oil, peanut oil, sea water, fresh water, olive oil, corn oil and automatic crankcase and gear oils:

http://www.csgnetwork.com/sgvisc.html

Question: what makes a quenchant "faster"? I think water is just about the fastest and noticed it had the highest specific gravity, but also the lowest viscosity, which apparently changes during agitation.

I'm wondering if viscosity is the main factor in determining how quickly heat is carried away from a blade? I wonder what oils at what temperature would meet the nose of 1095 (0.5-0.6 seconds) to form the maximum amount of martensite?
 
There are specific ASTM tests for determining quench speed such as the "Nickel Ball Test", there are a number of factors involved.
 
mete is right,as always.It is complicated - besides the "thin vs. thick" thing,there are the heat conductivity factor,vapor point (this is a big thing) and several other things.
 
Approximately speaking could you two experienced guys rate fairly common quench mediums in order from fastest to slowest for me please?
 
Fast to slow:
Brine -water - Fast quenchant oils (Parks #50,Brownell's toughquench, Chevron 70) - Medium quench (Park's AAA,Texaco C) -air
The fast group are good for shallow hardening,sharp nose (TTT curve) steels like 1095,W-1. The medium oils are for O-1 and L-6

mete will give a much better (and probably more correct) answer.I don't seem to have any good comparison charts on hand.
The trick to nailing HT is to know the steel and its hardening curve.Then pick the quenchant type for the job.A good shop will have three quenchants.
Water or water based mix - a fast quench oil - a medium quench oil.(Slow quenches are more useful to machine shops and foundries.)

mete - do you have any experience with plastiquench and polyquench?
 
www.heatbath.com/productt.htm is one source of info. Check other makers also. I have no experience with polymer quenches. Houghton has a website with extensive info on polymers . It shouldn't be complicated -water, fast oil, medium oil ,air. But yes you must know the steels ,you must match the quenchant to the steel. Too fast a quench it cracks , too slow a quench it doesn't get hard. For a number of reasons it's best to use proper quench oils.
 
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