A gentler quenchant

[evfreek]

Hi. As I promised, I will post an idea for saving oil. Unfortunately, a doggie ate my longer post last night, so I will just post the outline

Recently, when quenching some handled top tools in oil (to protect the eye), I experienced a fire . The stench was also disgusting.

I decided to try a polymer quench:

o did not want to buy the minimum quantity of Dow UCON A
o try to find an easier to source alternative
o do not use antifreeze: this is ethylene glycol, not PAG, and it is toxic
o ideas: CMC, psyllium seed powder (Metamucil), snails and slugs, shampoo
o settled on used disposable diapers from the local baby (cheap or free)
o each diaper contains about 12 grams of sodium polyacrylate ladder copolymer, with excess sodium ions
o MW is in the MD range, so only a small amount is required to boost viscosity
o slows down quench in the critical convection dominated martensite region
o enhancement must be at least an order of magnitude because oil is 10X and heat cap x density of water is about 3 x.
o simple experiment at a few ppt by weight shows promise

I am always reminded that anything I ever thought of has been discovered by another earlier blacksmith. Any experiences ? I checked De Re Metallica (Hoovers translation) but came up with nothing. There is some controversy, however with the interpretation.

[ThomasPowers]

The largest collection of odd quenchants I know about is in "Sources for the History of the Science of Steel" C.S.Smith

[bruce wilcock]

the softest quench is oil floated on water,push the job through the oil into the water and dont move it about,it only needs a small amount of oil just a skim ,to leave a coat on the peice as it goes into the water .

[BobStrawn]

Here I show my ignorance:
Here is what I think I know, but would not mind correction on.
A harder quench, as in cold water, shocks to very hard, but is can be quite brittle and may fracture some metals. A softer quench such as warm oil is less likely to warp or fracture the metal in quench. Some alloys produce more desirable crystals in one or another quench. Air would we the gentlest quench unless you include cooling in ash or pearlite as a quench.

Wouldn't placing the slab of metal in question in a big solid vise be a reasonable way to produce another gentle if not perfectly even quench? You could even warm the vise and fairly well calculate the final temperature if you weigh the metal and the vise.

Bob

[son_of_bluegrass]

Cooling between plates of metal (usually copper or aluminium) is called plate quenching and is applicable to some metals.

ron

[HWooldridge]

I have "quenched" a multitude of small items with a blast of compressed air. Colder than ambient air blown over the top of an item will cool it pretty quickly and of course, it's not as harsh as a fluid. In fact, this is the way I condition leaf springs when I have to rebuild a post vise. I forge the spring from a car spring, let it normalize, then reheat to critical temp and quench with compressed air - no temper.

[evfreek]

Bob, often evenness is more important than speed. That is why some people favor brine over plain water. Brine is faster, but more uniform.

The compressed air quench sounds interesting. I have waved pieces of air-hardening steel and gotten good hard quenches, even in fairly thick sections. I would be a little scared of using a blowgun, since it might just quench one spot well.

Thanks, Bruce, the suggestion of the oil floating on water sounds like it would save oil, but there still would be the stench and the fire risk. One would think that the diaper quench would smell bad, but it doesn't. The amount of diaper filler dissolved in a liter of water is fairly small. About 1 gram each of fluffed cellulose and sodium polyacrylate or polyacrylic acid and 20 or so grams of baby waste product. It is not even slightly tinged yellow, but I try not to touch it.

Thomas, I did a search on Smith's text that you referred to. Saw some posts on a "rainworm quench" but no diaper quench. It was actually something like this rainworm quench which gave me the inspiration. A bunch of snails and slugs got into my quench bucket. The effect on moderating the quenching vapor film was remarkable. I did not realize at the time whether it was surface tension alteration or viscosity, but after some reading, it is due to high temperature precipitation of the polymer. Snail and slug slime, and I would guess, chopped rainworm, would have some pretty high molecular weight components with interesting properties. I suspect that the ancient smiths did not realize what was going on.

The interesting thing about the diaper quench is that it does not harden plain high carbon steel completely. It does not even cause the scale to blast off. I can't wait to try it on something more discriminating, like 5160 or deep hardening 4140, or even D-2.

[BobStrawn]

This has helped fill in a lot of blanks in my data. I knew brine was faster, but not that it was more even. Makes sense though, better conductivity, higher thermal mass and an elevated boiling point.

So are you looking for a less conductive quench with an elevated thermal mass and an elevated boiling point? My wild crazy guess would be that lecithin might do just what you want. It is available in most health food stores and is a nice lipid that will combine with and even thicken water. Use about one part lecithin to 16 or more parts water if you want them to mix well.

A low sodium/electrolyte protein drink quench might also have the qualities you are looking for. The right carbohydrate might work too. In general, the more different stuff you mix in, the greater the thermal mass and the higher the boiling point.

Bob

[bruce wilcock]

the oil on water is only a light sheen not enough to burn apart from a flash thats put out as you go into the water ,

[ThomasPowers]

Plate quench can be quite fast if the metal makes good contact with the piece and warming the plates does not slow down how fast it removes heat much unless you are heating them way hot!