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can high alloyed tool steels quenched in brine ?

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It is will known that most of tool steels are quenched in oil to prevent cracking and distortion which appears when quenching in water due to non-uniform cooling caused by formation of insulating vapor blanket "film boiling".

but according to some  literature [1] using 14% brine solution or 1% polymer solution eliminate this vapor blanket so we can expecting more uniform cooling compared to water quenching.

according to another literature [2] the probability of quench crack formation firstly increases to the maximum value, and then decreases to zero.

increasing cooling rate is possible by using strongly circulated brine quenching bath, and using brine eliminate vapor blanket which ensure uniform cooling.

so, can we excepting maximum hardening depth, minimal cracking and distortion and eliminated fire hazard by quenching high alloy tool steels i.e. O1,M2,..etc. by quenching in circulated brine instead of oil ?

[1]: http://www.gmferd.com/journalcra.com/sites/default/files/31683_0.pdf
[2]: https://www.researchgate.net/profile/Nikolai_Kobasko/publication/260124962_Steel_Superstrengthening_Phenomenon/links/5692bca808ae0f920dcd8fb1/Steel-Superstrengthening-Phenomenon.pdf

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Great info Iron Madara.. 

I to have looked at a bunch of research 30 years ago as 90% of the steels for knives, swords and such even when considered an oil hardening steel has been quenched in Water.. 

Was taught water, brine, oil in relation to hardness and brittleness as more to less with oil being a tough quench vs brittle.. 

  I have gotten to the point where good practices because of experience has made it very consistent using water for 5160. 4140, 1045, 1060, 1080 and 1095..  

With this said I also except that there will be some failures from water cracks but the failure rate is 0.05%...  

My understanding with the research glimpses I have looked at now (last 5 years) runs here:

There is some literature out there now saying the brines will give a harder hardness because of the factor of cavitation being minimized even compared to oils which would equate to a harder object..   There  are also special multi time oils vs straight time.. 

The question for this becomes why harder..     There is a limit to how hard an object can be and still be useful..  LOL..   Or is there..    Once we understand steel matrix we can see that steels depending on use can get harder over time after being quenched and other methods for creating a more uniform matrix via Sub zero quenching, etc, etc.. 

From a professional knife or sword maker this could be great info and look forwards to a more indepth discussion.. 

I'll read the info you posted more as I just glimpsed it.. 

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Shape and mass of the piece makes a big difference too.

However I feel a basic issue is with this line: "It is will known that most of tool steels are quenched in oil"

I feel it should read: It is well known that most tool steels are quenched in a wide variety of quenchents based on alloy, use, configuration, mass, etc

I would certainly not heat treat M2 the same as O1!

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On 12/26/2018 at 9:21 PM, ThomasPowers said:

I would certainly not heat treat M2 the same as O1!

correct. nor would i water quench steels designed to be oil quenched. 

RTB is the golden rule here,,, read the book.  meaning follow what the specs state. they are designed that way for a reason.

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Happy almost, Madara

Your question seems to be from the understanding that there is "One" answer to the question. There is not "One" answer. Different metals will quench at different speeds (k/sec). Different cross sections will also quench at different speeds. Different quench mediums will cause the metals to also quench at different speeds. Different motion/movement in the quench medium will also alter the quench rate. Every metal has a data page, what it is made from, what it is made for, what its Heat Treating properties are. What to use as a quench medium, etc.  That doesn't mean always, that nothing else works. That means that, the manufacture of that particular product 'Recommends' a certain criteria to attain known/consistant results.

The correct answer is "Absolutely Definite Positive Maybe".

Enjoy your Journey. Some peoples whole working career, is trying to understand the correct answer to your question. The School of Hard Knocks is your best Teacher!! To test your work-piece, you will need a means to test the pieces hardness and the depth of hardness. Yes, there are Hardness Testers and there are different scales to measure/relate to.

But, you just asked a simple question...................


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Note too that the book suggestions are generally based on a 1"  thick section. ---few of my blades have a 1" thick section---anymore...

I once met one of the BNS and saw his heat treat handbook that had nearly as many page inserts in it as original pages in the alloy sections he used.  To paraphrase a certain movie---they were "suggestions" not laws...

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  • 2 weeks later...

Cpm steels like cpm10v a cast iron alloy say they can be "interupt quenched" in brine. 

If its an air hardening steel you would be basically just dipping in and out like a peck, just enough to make a steep drop in the phase diagram, avoiding any curve time in the water, just a very quick peck on the edge no more then about an inch or less.

You generally want a higher austenizing temp to do this though, it works okish with A2.

I never could quite get that technique right though I would either take too long trying to allign it or get the angle wrong and warp my blade from uneven hardening on one side being deeper then the other.

iv seen alot of normal water interupt into oil but mixing the two isnt my thing.

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Welcome aboard Iron Madara, glad to have you. If you'll put your general location in the header you might be surprised how many of the gang live within visiting distance.

You're on the slippery slope of trying to find the "perfect" solution to your question. Unfortunately perfection doesn't exist, even a "best for" is rare and hard to achieve. There are just too many variables to have a single solution.

Even different production runs of an alloy will have different properties if the end user is trying to push the envelope. MAX hardness of an alloy is rarely if ever desirable, this is why you temper tool steel back from as hardened. Max hard is most likely brittle, sometimes it'll self destruct if left as quenched.

There's nothing wrong with pushing the envelope but doing it without knowing what you're doing is a better recipe for failure of the sort that discourages the kind of perseverance necessary to actually push the boundaries back any. If you start your tool steel work following the manufacturer's recommended heat treatment till you have it mastered you'll know enough to maybe be successful pushing the limits.

We're not trying to discourage you, we like helping folks learn, they tend to show off their projects and we get to look at cool pictures. It's a good thing, honest.

Frosty The Lucky.

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Well you can quench an oil hardening steel right into the same oil used to temper, the temp just drops down and continues out to tempering. If not you have to keep it above 275 or you lose martensite.

Its a more industrial process though, but bainite is heat treated a similar way with molten lead, the steel gets quenched to 1000 and kept there for however long.

Im guessing your objection is safety reasons? 

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Mnnn i used to think that way before i started expirimenting with quenches at welding temps, im not quite sure how to describe it but theres no bubbles rather the steam expands so quickly it dissapates through the water and just permeates from the surface like a smoke grenade. 

I think there would be a similar effect if the water was already boiling given the energy required to vaporize it would be minimized. But im just theorizing.

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Similar so figure that the salt isnt bonded to the water but freely suspended in the water. The steam explosively expands gets saturated in the water like the salt. There is a volume ratio somewhere to this i havnt figured out.

But what happens if the water is already over saturated with salt and boiling.. Would the effect be excellerated and be possible with a drop from 1550 to the waters boiling temp? 

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