Last question for a while ,I promise.

flatblackcapo

flatblackcapo

Well-Known Member
Ok I hate to even ask this one but I must do it. I have two knives in 1095 that I need to heat treat. What would be the best quenchent that I could use with out buying 5 gal of Parks 50 ? I would like to take the safest route so I guess oil would be better brine for my purpose. I do not plan on doing any more blades in 1095 for a long time ,if at all so I don't want to spend a bunch of money on a quench oil I will use one time and I am pretty sure there is not a big market for lightly used quench oil.Thank you for your time and sharing your knowledge.
 
It's going to depend on the 1095. If you got it from The New Jersey Steel Baron then the canola oil might be ok. If it's from another source you may have to be prepared to go to brine. I ran into the same problem early on. Aldo hadn't opened up shop and all I had access to was some low manganese 1095 that wouldn't harden in the oil that I was using. I didn't know about parks #50 and couldn't have afforded it if I had. I went to brine and did ok.

Doug
 
Thanks guys. Please do not take this as I am disagreeing with you. I was under the impression canola oil behaved like a medium speed quench and 1095 needed a fast quench. Is there any truth to that or am I completely off base?
Doug, It was the first piece of knife making steel I ever bought so of course I bought a hunk of .250 lol. Not that there are not perfectly useful uses for .250 stock. I just laugh at myself because .250 1095 seems to be the go to for newbees . I think I bought it from Jantz or Texas knife supply. Would it be about the same manganese % as Aldo's?
I will post a pic of the ...um.....knife that I wish to quench. Maybe it will help clarify my needs. I am also doing HT on another guys knife and I just realized I need more info from him so I can do a better quality job
9411322639_7d89fe0e02_b.jpg
[/url] WIP #1 by pokeyoureyeout, on Flickr[/IMG]
9414087768_f7859362c6_b.jpg
[/url] WIP #1 by pokeyoureyeout, on Flickr[/IMG]
I guess it is more of a stupid big 1/4" thick kamisori than a "knife" haha. It is the deep hallow that gives me pause about using brine,because of the added possibility warping and the fact I have never brine quenched anything in my life. Thanks for the help folks and please keep the suggestions coming.
Kevin
EDIT the pics are when it was just rough ground. I would not try to quench anything in that condition and expect a good result.
 
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Canola oil, speed wise, is as good as it gets other than Parks #50, for an oil quench. Brine is tops, even over the Parks #50, but you are at a risk of the it cracking. If you want to try brine, lower your critical temp to between 1450°, and 1470°. Brine is less violent than straight water, and much more even in cooling, but the risk is still there.
 
Could anyone tell me how to mix up brine and at what temp it should be at the time of quench. Also would anyone be willing to sell/trade me enough Parks 50 to do two knives?
 
LRB said:
Canola oil, speed wise, is as good as it gets other than Parks #50, for an oil quench. Brine is tops, even over the Parks #50, but you are at a risk of the it cracking.
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I think that's probably true.

With an atypical geometry and asymmetrical cross section like that, (which has a greater chance of warping),... the slower quenches might be better. It also looks like some course machining texture. This could also create problems with the faster quenches, in terms of stress risers and cracking.
 
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One said:
I think that's probably true.

With an atypical geometry and asymmetrical cross section like that, (which has a greater chance of warping),... the slower quenches might be better. It also looks like some course machining texture. This could also create problems with the faster quenches, in terms of stress risers and cracking.
Click to expand...
Thanks One. Sorry, I should have made it a bit more clear that the pics I posted are of the blade in its rough ground stage.I would never try to heat treat anything in that state.If I use a quenchent that is slower than what is called for won't I get a blade that is not hardened all the way through ?
 
The brine formula I was given and use is 13 oz salt, Kosher or sea, per gallon of water. Simply one standard 26 oz box of salt into two gallons. I mix it hot, but quench at 100°. Your thin blade will harden all the way through, but I still think warm canola oil might be best. Can you try a piece of scrap ground similar first? Maybe two. One for canola, another for brine?
 
If the spine of that blade is 1/4", the same as the stock it was ground from, I doubt that you will get hardening all the way through all the way to the spine if you keep the grain small. There is the possibility with something like 1095, though not likely, that the grain is over refined and the nose of the cooling curve is pushed too far to the left to allow the steel to harden at all.

Doug
 
What is this nose that you speak of?:confused2: Seriously though,I have heard this term used but I must admit I do not know what it means. Also, is it acceptable to not get hardness all the way through the blade? I will go back to the stickies in the meantime. Thank you all for your help.
 
flatblackcapo said:
What is this nose that you speak of?:confused2: Seriously though,I have heard this term used but I must admit I do not know what it means. Also, is it acceptable to not get hardness all the way through the blade? I will go back to the stickies in the meantime. Thank you all for your help.
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1095ttt.jpg


See the point on the dotted line that looks like a great white sharks nose at around 1000F in the image (copyrighted by cashenblades.com) above? That is what Doug is referring to. It is basically the critical point that determines if you will be able to fully harden a piece of shallow hardening steel. The dotted line indicates the point at which the austenite you made by heating will begin to transform into other phases. At that temp of the nose the other phase will be pearlite, a soft and unproductive phase for finished knives. The next fine dotted line over is the 50/50% line that will mean you can only achieve half of the hardening operation, and the last line means you have blown it entirely and the knife will not harden at all.

If you quench fast enough you can stay entirely to the left of those lines an not make any pearlite. When this happens you will get the maximum martensite (the actual hardened phase of steel) when you reach the Ms point around 400F. So the Holy Grail of fully hardening these steels is to keep it to the left of that nose at 1000F, however many things affect where that nose rests and the more grain boundaries and fine particles that are present, the more to the left that nose will come, and the narrower will be your path to successful hardening. So very fine grained simple steel with excessive carbides out of solution is very difficult to fully harden. As with all things, there are always trade-offs:2:.
 
Shallow hardening steels like 1095 tend not to harden all the way through, hence the name "shallow hardening". On very thin sections they can harden clean through, but not on thicker sections.

What they are saying about getting around the nose still applies though. You want full hardness as deep as it will go, as a general rule.
 
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… just want to add that in this scenario, I think we’re really looking at a choice between brine and canola.

Sometimes, with atypical, problematic geometries, cross sections, textures etc., on difficult to harden high carbon steels, like 1095,… trying to push the entire piece to absolute maximum hardness with a super fast quench can often result in deformation and/or cracking. On the other hand, with a slower quench, you might be looking at sacrificing a point or two of hardness along the thicker sections of the piece,... with less chance of deformation and/or cracking.

It comes down to somewhat of a personal subjective judgment call. However, another "general rule" is, to use the slowest quench speed possible to achieve the desired properties for the end use of the tool,... and this is probably the most important..
 
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I think the topic question of this thread has been answered by a consensus of us who participated- if you do not want to buy an actual quenching oil, canola oil is probably your best option in both the health of the blade and the health of the quencher. Does the original poster have any other questions on this specific topic?
 
I agree with Kevin, and also think if there are any clarifications or explanations on the details/specifics necessary, over what we’ve covered, he should feel free to ask.

I think canola would be a good place to start and if it doesn’t give you what you are looking for, try brine... slower first, then faster if needed. In any case, keep the intended end use of the tool, (short term/long term), on the front burner.
 
Thank you very much Kevin and One. I have learned a few things in this thread. One of them is that I was mistaken in my assumption that canola oil was a medium speed quench.The other is what is meant by the nose.
I do have 2 more questions,one is their any source for a professional quenchent that would be more ideal than canola that would cost less than $40-50?I do realize the benefits of a quenchent that is specifically engineered for the type of steel I am using.I just can not justify spending over $100 to quench 2 blades.The 2nd question is at what temp should I have the canola oil.Is there a source to find the recommended quenchent temps for some of the more common knife steels or is it quenchent specific ? I think that was more than two.haha. Thanks for your time and patience.
 
I think it's a bit of a misconception that any quenchant should be chosen based strictly on the steel type. It's just not that simple. Geometry also plays a major role in heating/cooling speeds etc. The main advantages of commercial quenching fluids over canola are simply that they can be bought in different speeds and tend to be cheaper in the long run. For just two blades it probably doesn't make any sense metallurgically or otherwise. We've discussed this in detail on other threads and from a purely metallurgical standpoint, canola is pretty hard to beat. It is comparable to the faster commercial oils, and in some ways and/or cases even better. The temperature of the medium effects the viscosity, higher temp./lower viscosity, the faster the quench. With canola 130 is about optimal for speed, but for a slower quench it can be used at room temp.

Brine is the fastest we've discussed, but the problem is that along with being fast in the initial part of the quench it is also way too fast for most blades in the latter part of the quench where transformational stresses are a concern. This is often when the distortion and/or cracking occurs.

... All of that being said, it would be very difficult to say for certain which quenching medium would give you the best results on this particular example, without actually trying them.

... You still get to play "scientist". :)
 
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Flatblackcapo, since 1095 is one of the trickier steels to beat that nose with, you will need a good fast quenchant for full hardening and many that I know of which are sold in smaller, inexpensive quantities tend to be medium speed. Steel chemistry is the key component in hardenability, cross sectional thickness affects heat extraction, a function of mere thermal mass. We can banter back and forth all day on the topic but pearlite won’t give a flip about our beliefs, it will just form regardless when the heat extraction cannot exceed the steels chemistry limitations. And then if you are too fast for that same chemistry you will have issues in the opposite direction. When viewing the image of your blade, I would ask if it is critical that you harden the spine area as well? Under ideal circumstances Parks #50 could harden all the way to the spine, but most slower oils will at least get you half way up that blade, if full hardness is obtained at least ½” from the edge you should be good with full martensitic structure where it counts. So how thorough you want it to be is your call.

One option if you want the blade done optimally in a real quenchant is to see if there is somebody who is already set up with the proper medium and see if you could use their facilities or have them do it. This is one of the things that I always admired about the stock removal guys, compared to us bladesmiths, if they didn’t have the proper setup to heat treat something they didn’t let pride get it in the way of making the best blade they could and would simply send it to somebody who did have the best tools. Of course there is also something to be said for having knowledge and overseeing that the heat treat is done correctly even with the proper tools. Since the real main advantage of actual quenching oils is reliable, predictable and consistent results over the long haul, your momentary need for it sort of negates that, so as has been pointed out, canola at 130F may be best in your situation if you can’t make a visit to somebody who has the oil for the job.
 
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