Sand Pot, could it be a salt replacement.

Yeah I was only considering this for austenizing, or tempering personally. Salt obviously has it's advantages for marquenching, etc. I hold it to be a pretty universal truth that nothing is perfect, or without compromise, I expect this to be no different.
 
Also, I'd be curious if we can find out more specifics about the AO that Peters uses. Not sure if it matters but you can get different shapes of AO grit, such as spherical, and stuff that's processed in different ways. I'm not sure if this'll affect surface finish or not, but maybe they're using some highly specific type?
 
Jt I sent you an email but what your doing is amazing and I and I'm sure others hope you try and make these. I'd be first in line for one. Such a clever and simple idea well done sir.
 
Salem, i was taking about using it for austenzing for hamon. I know that for many applications, any "low temp" fluidized setup is not fast enough. But a device like I was talking about would only require a pot of oil and/or a pot of very salty water if you are brave and a very cold place to cover most everything that we might want to do. As for kitty litter, i have been told by at least one guy who does a LOT of forge welding that busted up soft fire brick is a better solution for a "disposable floor"
Salem Straub said:
From what I understand, a fluid bed quench will not reach the speed of fast oil or water or even salt, so hamons might be a no go entirely.
That said, using the more expensive shielding gases like helium and hydrogen expedite heat transfer, much above the qualities afforded by fluidizing with plain air or even argon. That, and the fact that the sand can be run at a lower temp than salt and that the cross sections being quenched are quite thin metallurgically speaking, leads me to think that it's not necessarily out of the question.

An interesting thing about fluid bed quenching is that the quench speed can be customized by tweaking the fluidizing gas, particle size, gas flow, and temperature of the pot.

Javan, I like the kitty litter idea! I have some cheapo clay litter in my shop, just for the welding forge floor. Might work!
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Absolutely and this setup sounds like it could get us closer to that ideal system without worrying about killing ourselves in the process. ;)
javand said:
Yeah I was only considering this for austenizing, or tempering personally. Salt obviously has it's advantages for marquenching, etc. I hold it to be a pretty universal truth that nothing is perfect, or without compromise, I expect this to be no different.
Click to expand...
 
Ok I pulled out my ASM book #4 and what do you know it has a section on fluid bed heat treating equipment.
And thy list from bad to good the way to make a defuser plate. The worst is a single oriface then is a bunch of small holes in a plate and the all time best is a sintered plate. Face palm, why did I not think of that. A quick search shows you can get stainless in a sintered plate. And Amazon has 10 micron 316 stainless sintered disks filtersthat are 3/4" in Diamater. Just to let you know 10 microns is about .0004 so no sand passing through that. But being that's it's common material I believe a few phone calls and we can get disks in the size we want.
 
I found a company that makes
Sintered screen mesh that's 5 layers and fused together. Thy will go as fine as 2um but I think that's over kill. Thy will even cut it into disks for a good price. The only hitch I can see is scaling if running air. But with this type of diffuser I don't think we need to go crazy large in diamater for our tube. If we went say 3" sand pot and built a proper defuser that would load from the top and the gas line would run up the side of the pot and with proper regulation I believe argon injection would be more the feasible and would also preserve the defuser from scaling. I don't think you would really need to keep the argon running while its heating. Just purge the pot and heat. Then start the flow and insert the blade.
 
Ah a little late to the party. I figured someone made the stuff because I know it's used in things, I just didn't know what it was called so I was getting nowhere in my searches.
 
I would not think a fluidized bed pot would work for quenching. The heat transfer rate would be far too slow for most all steels except stainless. It would be roughly equivalent to cooling in a moving air stream.

What it does work well for is any task that requires even heating. Obviously, austenitization and tempering come to mind. Other HT tasks like normalization should be simple with the cooling time between cycles being the only constraint. Perhaps even spheroidizing and annealing could be done with moderate length soaks.

My current thought is that this system would work very well for forging and such, especially on thick billets. The billet/bar could be placed in the sand and removed when ready to forge. Because the temperature is controlled, overheating of the edge/tip and thin sections would be eliminated. If you want to forge at 1950F, set the pot for 1950. I think re-heat time would be fast enough. This would also allow multiple billets or blades to be worked on, as the ones in the pot are just sitting there ready to go as you work on one at a time.
This could provide a positive answer the age old question - "Can I forge with my HT oven?"



Salem, JDM's question on the clayed blade would be for austenitizing, not quenching. It might work - as long as the clay is not scrubbed off by the sand. This would take some experimentation. There would also be some degree of contamination of the sand by the clay. This could easily be dealt with by screening the sand regularly .... which is probably a good idea anyway.
 
Wow! I can actually contribute something!

Sorry i am on my phone but do a search for carbonation stones used in beer tanks. They are made from sintered stainless steel and usually have either 2 or 5 micron pore sizes. You can get small ones from places like morebeer.com for around $20. Bigger ones from gwkent.com.

Mike Pensinger
Brewmaster
Parkway Brewing Company

Sent from my SM-G920P using Tapatalk
 
Stacy, there is an entire book on fluidized bed quenching referred to in this thread. If you go there, and other places as well, you'll see charts and graphs with cooling curves for various quenching media, and various configurations of fluid beds. It's something that's done in industry- like salt, it may be an option for marquenching or austempering. I believe experimentation is warranted.

And yes, I realized that about JDM's post. You are right, screening occasionally would be a good idea. (If you have a large diameter sand pot, keep it covered if you have cats.):barf:
 
http://www.mantectechnicalceramics....ramics/fluidisation-and-aeration/fluidisation

I think the link above will have what will work if you want fancy.

In some water heaters a ceramic air inlet is used. It allows air flow in but won't allow flame out in case of a flammabable vapor ignition event like when someone spills gasoline in the garage. I think a disc of that type of material would work.

Otherwise why not simply put a soft fire brick in the bottom with the air supply below. Seal around the edges of the firebrick with refractory cement? Easy diffuser that almost everyone that has a forge has?
 
A few people have mentioned soft fire brick but I don't think is will let air pass through at least not at the pressures we are considering using. But I have never tried to blow air through a fire brick.
 
Salim. Just a shout out. I just saw your home is in Tonasket. I grew up in Republic (well Malo if that is a place)and then we moved to Colville. Now I live near NYC and miss WA. Lol. Its good to see someone from home on here.

Sorry for the derail.
 
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One of the articles I read indicated that quenching thick sections was entirely possible by fluidised bed. It required a slight drop to the bed temperature to achieve the same result compared to a salt bath for marquenching. So quenching will be entirely possible. My ignorance with steels that require a very fast quench would be the concern I tend to use forgiving stuff and the quench speed is slower than salt but faster than air.
 
Yeah skil, I know Malo. Bought a pair of tongs there once, at the trading post. Come visit if you're ever back around!

Gjnza, that's what I'm saying! May work, for slower steels.
 
Very interesting thread! Crazy thought, but if there was any way to keep the pot vibrating ( like a vibratory stone washing bowl) , would that achieve the same effect as fluidizing the media keeping it in circulation without the added cost of a shielding gas or possible loss of heat from injecting air?
 
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