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Glycerin quenchant

Posted by jimmyh 
Glycerin quenchant
January 20, 2019 01:56AM
The boiling point of glycerin is about right to achieve rapid cooling down to near Ms and then slow cooling from there, which sounds promising. I couldn't find anything about quenching into nearly pure glycerin, so I decided to run a quick and crude test.

I heated up a 1/2" bar of steel until it was glowing and quenched it into either water, glycerin heated to 185f to reduce viscosity, or some old soy oil. I then checked the temperature of the rod after varying amounts of time in the quenchant. There are a lot of sources of significant error in this test. For one, the IR thermometer sensor is larger than half inch diameter and would therefore underestimate the temperature of the rod ("190f" would sizzle water). I also didn't measure the behavior up near 1000f where the pearlite nose lives, and perhaps differences in vapor blanket behavior changes the shape of the cooling curve.

It seems pretty promising though. Hot glycerin only took about 40% longer than pure water to reach "450f", yet is like oil in how slowly the temperature drops once it reaches Ms temperatures. Here's the data.

Has anyone played with it or similar quenchants, or have any reason why it might not work well?

Edited 1 time(s). Last edit at 01/20/2019 01:58AM by jimmyh.
Re: Glycerin quenchant
January 22, 2019 11:57AM
Interesting. Maybe it was similar properties to the propylene glycol in antifreeze like how Parks 50 is used as a quenchant.

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Re: Glycerin quenchant
January 25, 2019 02:53PM
I like this glycol cooling characteristic,

I remebmer polymers to be used as quenchants to be faster than oil but not as fast as water,
perhaps from practical experience sometimes it gets burned onto the blade and apart
from being hard to put off it would also create an insulation during the quenching
that would cause inconsistent ht and dimensional instability.

If glycol does not do this it is pretty much ideal..

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