Brine Quench Revisited...

You keep mentioning "no pitting and no scale" as a benefit to this brine quench, pitting and scale isn't formed in the quench it is formed in the forge. Which leads me to beleive that because scale usually forms at around 1500F depending on the atmosphere, so that would be the reason for no scaling and pitting is scaling on a smaller level, also the lower temperature would be helpful to a blade surviving the water quench, there is too many variables here for you to say definitely that this works better than a proper 10% solution.

There is most likely a logical reason why industry set the optimal solution at 10% because A-lots of money testing in REAL laboratory conditions proved this to be true, B-they found that slowing down was useless, because then you could just quench in oil if you wanted a slower quench.

I have some really good info on brine quenching, I have seen firsthand a 99% success rate with it with 1075, and around an 85% success rate with 1095, ask a Japanese smith about THEY'RE success rate sometime. Like any good tool it is meant to be used properly, and if used differently than that it is meant to be, then used with common sense. Because most shun industrial methods due to the fact that usually blade cross sections crack in brine or water when alot of the steels we used are designated "water/brine quenching"folks think that some modification to industrial methods and techniques is warranted. Any other time I would probably disagree, but with brine quenching which i have done with swords (3 foot, complex geometry, not 3 inch knives) a fair bit, I can say that if you look at brine quenching with a different mindset, and think it through using SCIENCE and the information available already OR JUST A DAMN TTT DIAGRAM and some good old common sense, you would smack your head and go "OH DUH" and would understand, then be able to brine quench to your hearts content just about any steel you want.

I'll wait to see if anyone is even interested in hearing it before I take the time to type it, or if they just want to talk about adding enough salt to water until you get to the point where you are hardening AND etching your blades at the same time :yawn::rolleyes::)
 
Sam Salvati said:
You keep mentioning "no pitting and no scale" as a benefit to this brine quench, pitting and scale isn't formed in the quench it is formed in the forge.
Click to expand...

I guess I could have been more clear and said that the scale all or 90% popped off in the quench leaving the blade free of scale; that is what I meant and what was there easily rubbed off with my fingers. A blade that is not hot enough to harden would still have the scale on it.

Oh, and I'm interested in hearing what you've got on brine quenching, Sam.:thumbup:
 
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Sam Salvati said:
There is most likely a logical reason why industry set the optimal solution at 10% because A-lots of money testing in REAL laboratory conditions proved this to be true, B-they found that slowing down was useless, because then you could just quench in oil if you wanted a slower quench.

I have some really good info on brine quenching, I have seen firsthand a 99% success rate with it with 1075, and around an 85% success rate with 1095,

SNIP
I'll wait to see if anyone is even interested in hearing it before I take the time to type it, or if they just want to talk about adding enough salt to water until you get to the point where you are hardening AND etching your blades at the same time :yawn::rolleyes::)
Click to expand...

alright Sam, you got MY attention

-Page
 
If you still get under the nose the way you want to, and it isn't causing other issues, I see no harm in adding more salt if it does indeed reduce the thermal conductivity of the brine, and thus make a more gentle landing. There are lots of things that "industry doesn't do" that industry actually does do, but only in specialized instances that don't justify documenting in a general topic metallurgy text. Things like that might be found in industry white papers that you might have to pay to read. If this works, I'm sure you're not inventing something new - but just because I can't find reference to it, I'm not going to assume there is nothing to it unless someone can show me something that contradicts it.
 
There has been OH so much disdain lately for science on this forum, why should I share the fruits it has given me? Alot lately have been wanting to keep knifemaking simple, I am not here to spit on them, in fact I don't even own a pyrometer OR salt pots and happily forge away and heat treat by eye and magnet. but for those of use who have taken our own knowledge and practice to the next level (and I am only barely above coil springs and motor oil :)) only to get knocked for our "expensive" quench oils, why should we give input when it might fall on deaf ears?

I guess I am just sore lately from the turning of this forum of late, from a place to come to get good credible knowledge to a place where the tomfoolery outweighs the good threads when there is other outlets for that (W&C or The Cove). And wonder if I should join the ranks of the lurkers who only look in once a month or those proffessionals who have left outright because why should they use they're spare time and EXTENSIVE self earned knowledge to give info on threads only to get bumped off the bottom of the page by a 7 page post with basically jack $&(^ in it.
 
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Sam Salvati said:
There has been OH so much disdain lately for science on this forum, why should I share the fruits it has given me? Alot lately have been wanting to keep knifemaking simple, I am not here to spit on them, in fact I don't even own a pyrometer OR salt pots and happily forge away and heat treat by eye and magnet. but for those of use who have taken our own knowledge and practice to the next level (and I am only barely above coil springs and motor oil :)) only to get knocked for our "expensive" quench oils, why should we give input when it might fall on deaf ears?

I guess I am just sore lately from the turning of this forum of late, from a place to come to get good credible knowledge to a place where the tomfoolery outweighs the good threads when there is other outlets for that (W&C or The Cove). And wonder if I should join the ranks of the lurkers who only look in once a month or those proffessionals who have left outright because why should they use they're spare time and EXTENSIVE self earned knowledge to give info on threads only to get bumped off the bottom of the page by a 7 page post with basically jack $&(^ in it.
Click to expand...


Perhaps I'm misreading this, but if you're suggesting that someone on this thread is disregarding science, being insincere or foolhardy, or is being complaisant in wasting a knowledgeable person's time, I wonder if you and I are reading it differently. I don't see it as one of those threads. I read it as an honest question looking for scientific input about a reasonable tweak to someone's brine quench. Am I missing something?
 
No Nathan not this thread, this is a good thread!

Gimme a minute to type up my info, and stop bitching :D
 
IMO cracking in the quench occurs at the point where martensite starts to form. If you feel masochistic, grind out a blade and quench it in water in a well lit environment, and actually watch what happens without focusing or getting all excited and nervous about trying to get it to survive the quench go into it with the goal of cracking it, I think you will notice that just about everytime the cracks will start to occur at the last couple seconds of the quench. This is of course barring the fact you are using a steel that is entirely unsuitable for water quenching such as O1 or 5160. That tells me that you have to halt the blade's cooling before it hits the "tink tink tink point :)" or the point where martensite starts (Ms on a TTT diagram) to form, to avoid the dreaded ping. This is what marquenching is, quenching down to the martensite formation start point, holding it there for everything to equalize out a bit, then letting it air cool and form that good hard steel nice and easy.

So the goal will be to cool the steel in the water to where it will get down to about 500F in the water, then get it to hold there. I am not sure of the danger aspects of putting a wet clay coated blade in low temperature salts, but I don't think it would be very good, nor do I think putting a dripping wet blade into an electric kiln or oven set at 450F is a very good idea either. The method I have used was 400F oil, and while it also isn't a good idea to put water into such hot oil, it atleast won't explode in your face or shock you to death, it at most will just overflow some bubbling hot oil, I will leave the safety aspects of dealing with that to the individual, but I will say it can easily be dealt with with a catch pan or bucket or leaving some expansion room in the hot oil tank and leather gloves and an apron and full face shield and such are common sense.

This will give you your water/brine quench, then your equalization medium. You will quench into the water for your predetermined amount of time based on personal experience or calculations based on the papers out there that provide the speed of a 4-5% mix of brine like the link Rusty McDonald posted or just a 3 or 4 second count (or look at the TTT diagram, how long will it take to get to the martensite start point with a very fast medium like water/brine?) Then go into your 400F-450F equalization medium, then out to air cool (which gives the added benefit of a couple seconds to straighten any warp you probably got from quenching in the water, one of the BEST benefits of marquenching IMO). If all done correctly, You have successfully beaten the pearlite nose, if you are going for a hamon you have gotten some great amounts of activity from the water/brine as well as positive curvature, and don't have a blade that is much shorter than what you started with (or a hand full of pieces).

In simple forms, you use the water to get below the pearlite nose and just above the martensite start point, the oil to equalize the blade just above the martensite start point (where the cracking occurs), and then still ambient air to finish everything off nice and easy.
 
I don't just use oil, use brine and a temperature stabilizing medium which doesn't have to be anything other than cheap free vegetable oil from wal mart that every cheap skate can find.
 
Sam Salvati said:
I don't just use oil, use brine and a temperature stabilizing medium which doesn't have to be anything other than cheap free vegetable oil from wal mart that every cheap skate can find.
Click to expand...

FWIW, I think it's prudent to suggest that folks wear gloves, and wipe down that 500 degree, wet blade with a rag before going into the oil...water into hot oil can be very bad and start fires if there's an ignition source...Unless you're talking about a room temp oil, but then you run the risk of creating a pocket of water at the bottom of your tank that is subject to rapid and freaky heating by blades plunged into it.

-d
 
deker said:
FWIW, I think it's prudent to suggest that folks wear gloves, and wipe down that 500 degree, wet blade with a rag before going into the oil...
-d
Click to expand...

Yeah, those wet 500 degrees blades with standing water on them are very... wait... huh? :D
 
I think it may be prudent to quickly switch tongs, there could be moisture trapped in the joint. I have to admit that I was like :eek: when I read Sam's method but I thought about it for a while and thought it might not be too bad, then I checked out the smoke points and boiling points of oils Canola seems to have a smoke point of around 450F, the boiling point is around 550F so it's not too bad.
 
I always find it funny when blacksmiths and bladesmiths, who regularly whip around 2300F degree steel and hit it with hammers, spray glowing hot flux all over they're shop, cringe at the thought of a little oil flare up or spill. Yeah might be a problem if your quench tank is plastic in which case darwin award for you anyway, but if your quench setup is atleast designed by a very smart monkey, there should be no safety risk involved.
 
"Smart Monkey" may be keywords here. As long as you're not quenching a run of 50+ blades and have an oil thermometer and enough oil volume, large enough oil tank etc, everything should be good.

At first I was having visions of a pot of salt water and a pot of hot oil sitting on a propane coleman 2 burner stove and hot oil bubbling all over a burner and things going BOOM but that isn't necessary or probable with an intelligent approach.
 
Sam Salvati said:
I always find it funny when blacksmiths and bladesmiths, who regularly whip around 2300F degree steel and hit it with hammers, spray glowing hot flux all over they're shop, cringe at the thought of a little oil flare up or spill. Yeah might be a problem if your quench tank is plastic in which case darwin award for you anyway, but if your quench setup is atleast designed by a very smart monkey, there should be no safety risk involved.
Click to expand...

LOL! Very good point Sam :D
 
Sam, I'd just like to say I really appreciate you posting that information. I feel it brings a whole new perspective to a lot of the issues experienced with 'water quenching' steels, especially 1095. Even though I have a fast quench oil Houghto K, I think it is quite possible that I may put it to the way-side and replace it with this. I always had in the back of my mind that I should pick up another 5 gallons of $100.00 quench oil but I genuinely think that is no longer necessary, which is good because I really like 1095.

Thanks again, Sam!
 
Sam Salvati said:
IMO cracking in the quench occurs at the point where martensite starts to form. If you feel masochistic, grind out a blade and quench it in water in a well lit environment, and actually watch what happens without focusing or getting all excited and nervous about trying to get it to survive the quench go into it with the goal of cracking it, I think you will notice that just about everytime the cracks will start to occur at the last couple seconds of the quench. This is of course barring the fact you are using a steel that is entirely unsuitable for water quenching such as O1 or 5160. That tells me that you have to halt the blade's cooling before it hits the "tink tink tink point :)" or the point where martensite starts (Ms on a TTT diagram) to form, to avoid the dreaded ping. This is what marquenching is, quenching down to the martensite formation start point, holding it there for everything to equalize out a bit, then letting it air cool and form that good hard steel nice and easy.

So the goal will be to cool the steel in the water to where it will get down to about 500F in the water, then get it to hold there. I am not sure of the danger aspects of putting a wet clay coated blade in low temperature salts, but I don't think it would be very good, nor do I think putting a dripping wet blade into an electric kiln or oven set at 450F is a very good idea either. The method I have used was 400F oil, and while it also isn't a good idea to put water into such hot oil, it atleast won't explode in your face or shock you to death, it at most will just overflow some bubbling hot oil, I will leave the safety aspects of dealing with that to the individual, but I will say it can easily be dealt with with a catch pan or bucket or leaving some expansion room in the hot oil tank and leather gloves and an apron and full face shield and such are common sense.

This will give you your water/brine quench, then your equalization medium. You will quench into the water for your predetermined amount of time based on personal experience or calculations based on the papers out there that provide the speed of a 4-5% mix of brine like the link Rusty McDonald posted or just a 3 or 4 second count (or look at the TTT diagram, how long will it take to get to the martensite start point with a very fast medium like water/brine?) Then go into your 400F-450F equalization medium, then out to air cool (which gives the added benefit of a couple seconds to straighten any warp you probably got from quenching in the water, one of the BEST benefits of marquenching IMO). If all done correctly, You have successfully beaten the pearlite nose, if you are going for a hamon you have gotten some great amounts of activity from the water/brine as well as positive curvature, and don't have a blade that is much shorter than what you started with (or a hand full of pieces).

In simple forms, you use the water to get below the pearlite nose and just above the martensite start point, the oil to equalize the blade just above the martensite start point (where the cracking occurs), and then still ambient air to finish everything off nice and easy.
Click to expand...

As someone who is about to try a brine quench for the first time in a long time (and all previous attempts went 'tink' in a most dramatic fashion), thank you for that information!
 
Thanks, all,
I had seen onyoutube and read on the net that with oil you could burn down the barn(house) I got my neigbors a little upset melting lead for my other hobby. Thanks again, bullet
 
Sam,
I think we know each other well enough that you will take my comments as questions and opinions - and not attacks on you personally.
I have followed this thread and not commented, thinking that most would see the problems with it, and it would fall away, but it is back, so I am going to post my thoughts.

Have you actually done what you are suggesting. You comments imply that it is just an idea you have. If so, I would recommend that you try it in a fireproof building while wearing a safety suit....with plenty of fire suppression and extinguishing equipment handy.....and post the results. I doubt that you will get the hamon you talk of.

One part of your post had to do with the formation of a great hamon and still having the blade above the MS. Those two things can't happen at the same time. The hamon is a function of tiny martensitic crystals forming at the boundary line between the already formed martensite edge and the still austentitic body of the blade. The steels that form a hamon will be shallow hardening and low alloy, so the edge will have already converted to martensite in the water quench. If you delay the formation of the pearlite in the rest of the blade , it won't change the edge, but may move or erase the hamon.
When the spine and body of the blade convert into pearlite, the small crystals of martensite ( nie and nioi) are trapped between the two structures, creating the hamon cloud ( nioi) and the tiny glints above it (nie).
I don't know what the results of your procedure would actually bring, because I have never tried it or known of anyone doing such to get a hamon. It just seems that while it may well prevent some cracking by delaying the Ms, it also seems that it would greatly modify ( or eliminate) any formation of an active hamon. Hamon formation is a bit of a crap shoot as it is, and any change would require extensive experimentation to determine the parameters needed to place the hamon where you want it (if one forms at all).

My take on blades cracking is that it mainly occurs during the conversion of the edge into martensite below the Ms point, where the steel expands at the speed of sound. This is the point in the quench where sori ( zori) is created. The conversion is so rapid that the stress may not be able to be distributed into the blade evenly, and a localized point will break or crack.The wilder the hamon being attempted, the more localized spots there are. This is where the ashi lines help in spreading out the stress through the many slightly softer ( mixed structures of pearlite mixed in the martensite) areas nearer to the edge than the hamon will be. Cracking is somewhat placated by an interrupted quench,where you lift the blade into the air after the edge has passed the pearlite nose, but before the body has cooled much at all.At this point the ashi will become a mix of pearlite ( just a tad) and mainly martensite. The timing is very exact. I doubt that you could get it from water to oil fast enough to avoid cracking....and still get as very active hamon.

All that aside, I find it disturbing that you would suggest heating oil to 400F and then plunging a hot and water laden object into that oil. If it was done in five gallons of oil in the bottom of a 55 gallon drum, you might be a bit safer, but if it is done into any normal size and shape quench tank or a turkey fryer, I would say it is a recipe for disaster. Even if it didn't boil over, which I agree isn't likely, the mere use of 400 degree oil without industrial level equipment to do the process in makes me cringe.

Again not picking on you, Sam, just stating my thoughts on getting an active hamon and the merits and problems with your suggested procedure.

Stacy
 
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