52100 (Aldo's) alternate heat treat= Epic Fail !!!!!!

bluntcut said:
Carbon plays a central role in what the final structure going to be. I was wondered if there enough C aus-dissolved by your method for a C rich martensite matrix(MM). During temper, Cr alloying and cementite precip (FeC) with C from MM, which could lead to C lean MM....
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I suspect ^, accelerated softening of the matrix.

Willie71 said:
Epic Fail!!!!! I tempered a second time at 400fr, and the blade came out at Rc50! I'm going to redo it tomorrow with the thermal cycling that has been the standard. Thanx for the discussion.

:grumpy: :grumpy: :thumbdn: :foot: :jerkit: :confused: :p
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Rick hit on something I've wondered. Two schools of thought on thermal cycling. Reducing temperatures every cycle vs 1414 every cycle (just change it over to austenite). I understand that with certain steels and the way they're supplied, the higher initial heats are critical, but what advantages are there to going below 1414 during cycling down in temps vs just getting it past non magnetic for a few cycles?

Willie, were you able to re-do that heat treat?
 
I found some posts from a few years ago on knifedogs where Kevin Cashen noted that 52100 should be quenched after the first 1625f- (Post from 2013 says DO NOT QUENCH as there is risk of cracking the blade!!!!) treatment to get the structure "locked in" so to speak. If you don't quench the alloys and carbides can move into the grain boundaries. At the lower temps, below the 1625 normalizing temp for 52100, quenching isn't needed. He also noted that there can be two different spheroid conditions, one with fine carbides, and one with course carbides. Either is easy to machine, but he speculated the most common is the course carbide condition. If you don't know which condition you have at the start, going to the 1625 is the best bet (basically what Rick and Bluntcut said in the beginning. :) ) Sometimes I just have to learn the hard way. Now I know why.

Samuraistewart, I bough some dry ice today, so I will be doing some 52100, S35VN, and AEB-L today. I'll post the new results on the 52100 after I'm done. I'll compare 1475 with 1500, dry ice, and no dry ice and post those results. I will use the same thermal cycling for the coupons up to austentizing, then change for the experiment.
 
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+1. My understanding is that Aldo went to Kevin Cahsen for advice on how to treat this stuff and that it all comes sphereoidized. As such, you really should do the normalizing steps. The 1475F austenizng is done to get that high hardness and super fine grain and high edge stability. 1550F is for bearings where the wear resistance of big honking carbides is a good thing and things like RA and larger grain do not matter so much, at least as I understand it. Mr. Cashen told me that using this type of HT, 52100 is actually a better and tougher choice for larger blades than O1.
samuraistuart said:
I've received 52100 from different vendors lately, all of it is spheroidized. At least the stuff I've gotten. My understanding, as was mentioned, in order to get the carbides into solution, you have to perform the grain cycling steps (at least the first high heat), and the higher initial heat of 1650 or so is very critical. Of course, this causes grain growth, especially if left to soak for a while, so we grain cycle a few more times to reduce the grain size (introduce more nucleation boundaries). I believe this initial high heat puts all of the carbides into solution, so we can utilize a lower temp (1475 vs 1500 or 1525) to reduce RA. Most of what I have read concerning 52100 has been from Kevin, and 1475 with a good soak has been giving superb results, provided the steel is set up properly prior to hardening. Funny, I just HT a 52100 blade (copy of a Kephart Classic) last night. 1650F, 10 minutes soak, cool to black, quench. 1500F, cool to black, quench. 1400F cool to black, quench. (scale removed every cycle). 1475 for 15 minutes, quench in 120F canola oil. Temper 1.5 hours at 350. Clean scale off to bare steel again. 1.5 hours at 400. I would LOVE to have a hardness tester. There was a decent amount of decarb. I left the edge about .025, and sanding off the decarb has left an super hard edge about .005.

It would be really interesting to see tests done on triple quenching during grain cycling vs air cooling. As far as real world application, I don't think anyone would be able to tell the difference without microscopes and what have you. If the line is that fine, I tend to go with only air cooling in between thermal cycles, to reduce any chances of micro cracks that might happen during quenching, especially quenching from 1650.
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jdm61 said:
+1. My understanding is that Aldo went to Kevin Cahsen for advice on how to treat this stuff and that it all comes sphereoidized. As such, you really should do the normalizing steps. The 1475F austenizng is done to get that high hardness and super fine grain and high edge stability. 1550F is for bearings where the wear resistance of big honking carbides is a good thing and things like RA and larger grain do not matter so much, at least as I understand it. Mr. Cashen told me that using this type of HT, 52100 is actually a better and tougher choice for larger blades than O1.
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I have noticed a step up in wear resistance and toughness with 52100 over O1.
 
OK, a few questions.

I know very little about metallurgy, just barely enough to get the gist of what y'all are saying.

I have 6 3.5" (8" OAL) EDC Utility blanks ground out of Aldo's 5/32" 52100. I have access to a programmable Paragon, I just have no Idea what to do with it.

So the question is, what should I do for a heat treat recipe? I don't really wan't to dive too deep into the science of metallurgy at this moment (though I know this is an important skill for an aspiring knife maker), so i'm just looking for a bare bones recipe, no explanation needed.

Rick said:
1625F - cool to magnetic
1525F - cool to magnetic
1475F - oil quench here if you want
1300-1350F - (2-3x) before drilling, working

Final quench
1300F stress relieve(optional)
1500F hold 15 mins, oil quench

Can I skip the first steps because these are stock removal and go straight to stress relieve @ 1300, soak @ 1500, then quench in 130 deg. canola? If not, what is the proper sequence for these blades?

Finally, what should I be looking at for tempering cycle temp and duration?

Any advice is appreciated.

-Adin
 
You can skip those steps if you are a gambler.Read the thread again , all of it and you will see it is a good idea.I think all High Carbon Steel can benefit from a stress relief cycle.If you get into the practice of doing it every time,it will be part of your process.
 
The point of this thread was to see if a long soak could bypass the cycling. It didn't work. The blade is now at Rc60 after cycling and two tempers at 400f. I have the test coupons to clean up test and break yet. I was hoping to get it done on the weekend, but I always try to cram too much into them.
 
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To sum up my opinion... A long soak cannot refine grain. Only re-nucleation of existing grain can... but first you want everything uniform in size and well distributed... which is why a high initial heat is suggested. I'll ask Kevin, but from my understanding "locking it in" is really only valuable on the last cycle. You can do it on the others if you have control but for most of us cavemen, it is just more opportunity to muck it up. There has to be a compromise when your means doesn't match your aim.
ETA:
I found a very educational thread on 52100.
 
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I have read and studied a lot of Kevin Cashen's writings on 52100. The purpose of the first high heat (I've read that 1650 is better than 1625) is to release carbon into the matrix. The next temps are more for grain refinement.

I found this from a different forum and edited.

[Aldo's] "steel is at least 95-98% spheroidized so the normalizing is very important and your temp of 1650F is spot on to release the carbon needed for subsequent treatments, but normalizing almost by definition does not include a quench, just an air cool (and definitely no insulation or slow cooling). Quenching from 1650F will more than likely result in micro-fracturing if not all out cracking with this alloy.

You seem to really like quenching so I will say that you can quench on the next heat so long as it is below 1500F. Quenching can accelerate some of the grain refinement but it is not necessary.

The final heat will be for a much finer spheroidization that will be more friendly for your hardening operation so keep it at or below 1300F and just air cool

The next heat should be for hardening. Heat to 1475F and the 10 minute soak should be just fine if your other treatments did their job.

If all worked well you should be in excess of 65 HRC and ready for the temper. 2 hours total is fine. I like to start out at 375F for an hour and then check my hardness levels before bumping the temp up a bit for the second hour. This allows me to walk my exact hardness in and the repeated cycles tend to have a nice homogenizing effect on the desired properties."

(http://www.hypefreeblades.com/forum/viewtopic.php?f=4&t=662#wrap)
 
That thread in Hypefree was my exchange with Kevin.

As I understand it, Adin, you MUST go through the normalization steps to unlock the carbides from it's matrix and put them into solution, especially the initial heat of 1625 or 1650. But in order to keep the grain size down (which would be large after that 1650 heat), we thermal cycle (heat to just past non-magnetic and air cool) to reduce grain size. Some guys just go to nonmagnetic a few times, other guys do descending temperatures, usually a total of three thermal cycles with the first around 1650 and the last around 1350-1400.

Like Willie71 and gredpe3 said.....that was the whole point of this thread. You cannot just take it to 1500 and quench and expect great results. Can you make a decent knife quenching from 1500? Of course....it will take an edge and it will cut. But you won't be anywhere near the hardness needed for a good knife, and you'd be leaving meat on the table, so to speak.

I HIGHLY recommend using the formula I posted, or the one Rick mentioned. They're just about the same. Before I began using 52100, I was only familiar with 1084. WOW....what a huge leap in performance....IF and only IF it's done right. Also, let me mention that the HT formula was not from my trial and error, but from Kevin Cashen's experiences with this steel. While Kevin doesn't like to come right out and say, "Do X Y Z, in this order", he explains his thought process and WHY things need to be done, rather than just saying WHAT needs to be done. I've learned much from Mr Cashen, and I try to give him credit when telling others what I've learned from him. And there really isn't a right vs wrong way of HTing steel. Just what works. And what "works" for me is getting everything out of the steel that it offers.

1. 1650F, cool to black, quench in water.
2. 1500F, cool to black, quench in water
3. 1400F, cool to black, quench in water
4. (if needed) 1250 for annealing and stress relieving.
5. Harden at 1475, soaking for 10-15 minutes, and quenching in medium speed oil that has been warmed to 130F.
6. Optional cryo treatment. I have yet to try any cold treatments. There is dry ice/acetone or liquid nitrogen. Personally, I don't see how 52100 can benefit from cryo, since it's Mf is 235F...but I may just have to throw it in the freezer)
7. To temper....350F for one hour, quench in water, clean off any scale/decarb and test edge. Probably too chippy. Back into oven at 400F for 1.5 hours, cool to room temp.
 
Good post Stuart. I will bump my initial heat a bit higher after reading that. Kevin, has since told me that the magnet test is quicker and just as effective when multiple cycling. He said that all the steel needs to do is form a different structure, then you can cycle back up.:thumbup:

Are you messin' with us about the freezer?:confused::rolleyes:
 
Glad you caught that Rick!!! Shawblades ........ no, you don't quench into water from 1650F. "Cool to black, quench in water."
 
samuraistuart said:
Before I began using 52100, I was only familiar with 1084. WOW....what a huge leap in performance...
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If this is true for you, imagine what modern alloys utilizing new processes and technologies may unlock? Not trying to incite a riot, but that might be another avenue to pursue...
 
Matthew Gregory said:
If this is true for you, imagine what modern alloys utilizing new processes and technologies may unlock? Not trying to incite a riot, but that might be another avenue to pursue...
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I just did some S35VN and AEB-L. Too bad those steels won't get a hamon. I was looking through the steel selection at AKS, and there are some pretty cool steels there. The kiln just opened up a whole new world for me.
 
Willie71 said:
Too bad those steels won't get a hamon.
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Definitely an issue. Have to give up so much for what really boils down to an aesthetic.

...but it calls to me, even as I sleep. Gaaah!!

Been hankering to fiddle with some CPM4v, and maybe some of the Carpenter products. Your thread is inspiring me to get moving. Thanks!
 
If someone could develop a high tech stainless that would get a hamon like W1/W2, I would be all over it. It seems to be an impossibility though.
 
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