Oil quenching Stainless lets hear some stories

Guys, I have no dog in this one. I gladly offer what I have available to me to be of assistance. I personally have my own feelings about oil quenching these stainless steels but I really think it best I not get into that here because once I do I may become biased.

I have some no-carb paint that is good for, I think, up to about 1700 F. I may be wrong about that temp and will have to check. Even with that I have my thoughts about a consistant oil quench.

I will say this about what I would guess: A oil quench should give a harder and a deeper hardening. I will say this too: I air quench (foil wrapped) and I doubt it is a deep hardening but I have gotten 62'ish RHc from ATS-34 with a deep cryo temper along with a oven temper and about 58.5 without deep cryo.

Now, with that said I welcome any disputes but will refuse to discuss it further on this thread if I am to do any of the HT and testing. I need to remain neutral, and I am.

RL
 
Rob, I think the difference is the quench. Dr Jim in his books indicated that a oil quench will work for both 440C and ATS34. I tried it it dose work, I am not saying that it is the best there is however the blade that I spoke of earlier with the triple quench and triple draw was a very good blade. It was in a liner lock folder and I carried it for several years and did a great job it cut every thing from cardboard to pop cans etc.
I would have used a long soak put that is hard to do in a forge so I used what I had. I think this boils down to there is more than one way to do things. I have always had the file skate when doing my own heat treat on stainless. The Turco was only Good for one trip through the forge and I had some decarb to contend with but the blade was thick enough to grind out, what I should have done was retreat it after each heat. This test will teach us a lot and maby change the way we do things.
Gib
 
Matt, I have tried a shorter soak time at high heat with poor results. I should mention that I have a good Paragon programable furnace that I check regularly with a certified IR thingy that I borrow from time to time. I have quenched in oil, air blasted and press quenched, with press quenching having the best results. That being said I still send my big batches to Paul Bos for the best results ever.... Also I own a great Wilson hardness tester with all the test blocks, so I can somewhat test my results via the Rockwell Hardness tester. I was never able to achieve full harness with ANY high alloy, especially the stainless steels without soaking a minimum the recomended soak times.

The file test to me is really shaky, there is huge differences in the quality of files as well as sharpness of said files. An errant carbide on the file tooth can cause a scratch and make you say hmmmmm.

Dont get me wrong, I am trying to learn some new things here but my question is why do 3 quenches and have much more carbon burnout in an uncontrolled atmosphere rather than do it the way the manufacturer recomends once in atmosphere controlled conditions at a longer soak time? It is great fun to experiment for sure, I am all for that, my main interest is improving my knives.

Yes Gib, there are many ways to achieve good results, and the last thing I am trying is argue, I am just curious and have a little time on my hands. :)
 
I use an oil quench for D2 because I think that the faster the better. I use Turco and get it from the furnace to black in 1-2 seconds. I harden at 1870F and temper at 400F for a consistent HRC 60. I believe it makes the blades tougher due to smaller grain size, although I have not confirmed this with testing. It does eliminate carburization from cooling in air. I follow the quench with an overnight dry ice treatment and then triple temper.

Crucible reccommends an oil quench for S30V. I have used it with good success. You Have to get the wrap off fast. I get it into the oil while still light orange and have had the blades test out to 58-60 HRC depending on the temper.

I have been convinced by other makers posts to try quench plates and am looking for large pieces of aluminum at present. Once I do this, I plan to try some comparison tests. I contacted Crucible about this and one of their metallurgists assured me that quench plates were not the only way to go-if the metal was still orange when quenched it would be sufficient.

Don't try using turco on S30V, it breaks down at the temperatures it hardens at. I lost a batch of 5 blades to decarb that way.
 
Thanks Rob
Main reason I asked is I was hoping that you wouldn't say you were using the same method as me and it didn't work ;)

My set up is far from as controlled as yours, I guess I should buy a thermometer to stick in there and do some timing and recording temps and stuff so I know more about what I'm actually doing.

As far as the file test, I pretty much agree with you but I don't have access to anything better. I have one file that I use exclusively for it so that I have a way to gauge each knife to my previous knives after quench.It doesn't tell much in regards to others work but I can get some idea about my own.

So far blades have held up really well to toughness testing, so I think I'll back off the temper another 10 degrees and see if I can't improve edge holding, which is very acceptable now but not on par with ATS34 or O1 at RC60-62.
 
Matt, One file for the test is the key I have a old wore out Nickelson that I use and it gives very consistent results. Gib
 
I can sit on the fence on this type of thing. I am very much into the science of the hea-treat, but I also know that it can be an art as well. With this type of situation, there is always room for argument.

Personally, I don't like variables. The more I can cut them down, the better. When I was talking about my salt bath at the OKCA show, Wayne Goddard made stopped me and said, "Guys use salt and say they have more control, but I don't hear them saying they have better results."

Well, I'm saying I do! To me, whenever you increase control on ANYTHING, you will get improved results. If you can increase your control on grinding, you will grind a better knife. If you can increase control on a pitch, you will be a better pitcher....so on, and so on.

My biggest argument with the guys doing the funky heat-treat, is that many of them say they did this and that, so now instead of tempering at this temp, they only temper at this one 50 degrees cooler. I really don't understand that. If you take a blade and heat it for austenitizing, and then quench it (however you like) to achieve martensite....the harder you get it the more successful you were. The higher on the Rc scale it will read. The harder it is, the more in need of a good tempering cycle it is.

So if some whiz-bang home heat-treat gets that full conversion to martensite, how is it needing a lower tempering temp proof positive...rather than a short=coming?

I'm all about learning and improving...just like Rob said...NOT trying to start and argument.

:D Nick :D
 
I have to agree about the whole control thing and all that. I hope I haven't given the impression that I think what I'm doing makes a "better" blade. To be honest I have very little experience with 440C heat treated to manufacturers specs. I do know that I have done a fair amount of testing on my blades, and plan on doing more, and can say that the triple quench is an "effective" method.
I don't know if I'm getting it to full hardness after quench, but it does get hard enough. I'm not sure what the best temperature for tempering is yet. I did start out at 400 degrees, and was happy with the results. Edge holding was good enough but not as good as it could be, which is why I've backed off to 385. The blades are still very tough, and so I may back off more. I want the blade as hard as possible while still keeping the strength.
I will probably look into having a blade rockwell tested, when I get to the point where I think I have it all pretty well down. Judging buy how Arksansas and Waterstones will cut it, I would guess that I'm between RC57-60. Whether it comes out of the quench that hard, and tempering only releives stress, or if it comes out harder and tempering draws it back I don't know.....
 
This is just my .02 acquired from working with Devin Thomas for close to 5 years and dealing with both stainless and carbon steels. A steel only needs to soak long enough for the carbon to go into solution. In the case of most carbon steel blades usually no more than 5 min is necessary. Add enough chrome for the steel to become stainless changes the whole picture. The chrome and other elements added to the steel increase the time it takes for the carbon to go into solution. This varies with each different stainless. I tend to go with the manufacture specification on how to heat treat. It always yields me good results. The manufacture has done the research on how the steel responds to a specific set of parameters to yield the best results and I personally doubt I can improve on their results. Most manufactures will supply a table of soak times and temps to heat-treat and temper with RC values yielded at the different temps. I have followed the directions and then RC tested the blades and found them to be within 1 point if not dead on in most cases.

As a side note I routinely heat treat my stainless blades in foil and oil quench without removing the foil. I have never had the foil cause problems with getting the temp of the steel below the nose of the curve. I consistently get Devins AEBL and 304 mix stainless in the 58 RC range. This does not work with carbon steels at all. Turco tends to cause excessive pitting if you finish the blade above 220 grit and I’ve had it pit well below a 220 finish. I gave up on the stuff and don’t bother with trying to prevent decarb on carbon steels. I just leave the blade a few thousands over sized and throw it on the surface grinder after heat treat and clean it up.
 
Hopefully I will get the steel soon from Gib and perhaps this weekend can start as I am directed by him. Maybe we can have some RHc results by Sunday, depending on the mail man. If not, it should be soon.

RL
 
RL looking forward to your results.
What I have found with Turco is anything above 1750 and you get carbed and pitted blades. My Kiln comes up to temp VERY slowly so that may have something to do with it but I quench right at 1650deg on 440C and get consistant results.
 
Blinker, I don't believe my no-carb is good for the aust. temp. we need. Probably will quench and grind off the decarb on one side to get good tests.

Gib, very good and thanks.

RL
 
Good news; Gib's 440C test pieces have arrived.

Gib suggested, and I agree, that I should go by the book and use the data sheets for HT specifications. This will give us a good and published reference instead of going by someone's favorite homebrew recipe.

Gib, I need you to post any thoughts of how this is to be done before I proceed. Other than that I am ready to start, with this exception: I am not sure what we are testing for; is it oil quench vs. air quench or is it single oil quench vs. triple oil quench??

My no-carb paint is not specified for the temp. needed to properly austinitize 440C. Again, I highly suggest not coating the test pieces and not using foil wrap.

Gib, please advise as to the specifications I am to use. I await your post.

Roger
 
Roger,
1) a single quench in oil (ATF of something slimier) heated to 120 or 130deg then test then a triple draw @375deg and test

2) a triple quench in the same oil as #1 and test, a triple draw @375deg and test.
What we are looking for is the results of quenching 440C in oil with min. soak time. If you or any one else have any ideas this would be a good time to speak up. Gib
 
Okay. I use vegatable oil. I understand that I am to temper at 375 F. per temper session and I will allow the steel to still air cool to room temp. between tempers. I will quench to oil temp. and temper immediately. I understand that I am to heat my oil to approx. 130 F. for quenching. I will quench completely submerged in a back-and-forth cutting motion and uninterupted.

I would like to get started because I have much other things to do also this weekend.

If left to me, I will do a 5 min. soak per austenitize. I intend to austenitize at 1865 F. with no atmosphere control. I will wait until approx. 6:00PM EST and if I hear nothing else here I shall proceed.

I would like to ask permission to skip the test before temper. I fail to understand what it will prove and it will prevent me from tempering immediately. I will advise that if I have to grind decarb before the first temper we will get an improper heat treat (I must grind to relative flat to get an accurate test). PLEASE ADVISE.

Because of all these addendums I have been making to this particular post I will wait until 7:00PM EST time to see what additional direction I may receive.

RL
 
I would go ahead and temper immediately and not worry about the test after the quench for the time being. The final hardness is of more importance at this point.
Later on, I would like to know (ballpark, different with different equipment) how hard it is before tempering. Mainly to answer the question of lower tempering heats, and whether or not your temper is merely releiving stress from a blade thats close to target hardness right after quench or if its drawing the blade back from full hardness. Thats less of an issue than the final results though, and finding out exactly what the multiple quench does.

Just a suggestion its not my steel, and I will be interested in the results no matter how the test is done.
 
It is 5:53PM at the moment. I am heating the oil and it will be monitored using a digital thermometer that I have checked against other pyrometers. The temper oven is stabalizing at 375 F. and likewise being monitored. I will be programming the Even Heat in a short while. I will periodically post as things occur. I will be doing the single quench test piece this evening. No doubt it will be very late (early in the morning) before the third 2 hour temper is complete. I will be waiting until tomorrow afternoon to Rockwell the piece. I will allow the same amount of rest period to ellapse before testing the 3 quench piece so that all things will remain relatively equal.

All is well.

RL
 
Thanks alot for donating your time and resources to do these tests for us. For the most part, people are using the triple quench method because they don't have the equipment to follow the manufacturer's specifications, which means we can't do this kind of testing either.
I really appreciate it :)
 
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