52100 Heat Treatment

Carterwhopkins

Carterwhopkins

Joined
Dec 12, 2012
Messages
238
Hi....like many others, I have been lurking for a while and this is my first post. I have been making custom handles and sayas for Japanese cooking knives for several years. Recently, I started making my own blades, chef knives, using stock removal with Aldo's 52100. I have had several batches turn out well and the blades have good grain, edge retention, etc....I have been pleased with the results. I just moved from Miami to N. Carolina and did my first heat treatment yesterday and I am not sure about the results...the blades do not seem to be as hard. I was wondering if I need to adjust settings with the colder weather and higher altitude (approx. 2,300'). I am using an EvenHeat and quenching in canola. My treatment recipe is as follows:

1650F - 20min - oil quench
1450F - 20min - oil quench
1250F - 20 min - air cool to black, oil quench
1500F - 20 min - oil quench
425F - 2hr - water quench
425F - 2hr - water quench

I am open to any advice on this recipe and I am aiming for a HRC of 60-62.

Many thanks,

Carter Hopkins
https://www.facebook.com/CIIBladeworks/
 
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Carterwhopkins said:
Hi....like many others, I have been lurking for a while and this is my first post. I have been making custom handles and sayas for Japanese cooking knives for several years. Recently, I started making my own blades, chef knives, using stock removal with Aldo's 52100. I have had several batches turn out well and the blades have good grain, edge retention, etc....I have been pleased with the results. I just moved from Miami to N. Carolina and did my first heat treatment yesterday and I am not sure about the results...the blades do not seem to be as hard. I was wondering if I need to adjust settings with the colder weather and higher altitude (approx. 2,300'). I am using an EvenHeat and quenching in canola. My treatment recipe is as follows:

1650F - 20min - oil quench
1450F - 20min - oil quench
1250F - 20 min - air cool to black, oil quench
1500F - 20 min - oil quench
425F - 2hr - water quench
425F - 2hr - water quench

I am open to any advice on this recipe and I am aiming for a HRC of 60-62.

Many thanks,

Carter Hopkins
https://www.facebook.com/CIIBladeworks/
Click to expand...

Why you hold blade 20 min . on final quench ?
 
Those numbers "should" be giving you pretty decent results, but can be tweaked a little. Your normalizing heat of 1650F is good, your soak time there is good. You really should only be quenching ONCE if you're doing cycling at the temps you're using. So after normalizing, air cool to black or ambient. Your next cycle should be around 1550F, 10 minutes is plenty, again only air cool. Next cycle should be around 1500F, 10 minutes is plenty, air cool. Next cycle around 1450F, 10 minutes, air cool. You can go to hardening from here, you can also do a sub critical cycle if you wish, 1375F, 10 minutes is plenty, air cool. If no other machining needs to be done, you are ready to harden. Your heat of 1250F does not do anything other than stress relieve, but that has been accomplished already with your cycling (technically in your case, because you quenched from the previous cycle at 1450F, the 20 minute hold at 1250F will have slightly spheroidized the cementite). To harden, lower your austenitizing temp to 1475F, hold only for 10 minutes, quench in oil. You should reach around 67HRC, and a 425F temper should still be around 62-63HRC. 450F should be around 61-62HRC.

If you need to do more filing/drilling on the blade after your normalizing and cycling, quench on your last thermal cycle temp of 1475F, then "temper" it at ~1225F for a couple hours. This will spheroidize the carbides, making it very soft, but also ready to harden.
 
I do not understand why to hold 10 min. on 1475F 52100 steel ? I do it only for 2-3 min ..........
 
I follow AKS's recipe for hardening. Normalizing aside, I heated to 1600F for 5 min and quenched in oil, tempered at 400F and got 60-61 RC. They give an austentizing range of 1545-1615F and I generally use the higher end of the range they provide because of my furnaces heat zones, I get the called temperature near my thermo probe and lower temperature as I move away from it, so calling to the high end of the ranges specified generally gives me the most consistent results.
 
I don't have anything to offer sadly as I have not tried this myself,
but I would say the OP method seems very complicated as compared to simpler HT guidelines for 52100 that I have seen.
I'm staying tuned here as this is a steel I want to try on my own in a forge,
 
Austentizing a hypereuctoid steel above 1475f is going to result in retained austentite. Once normalized and cycled, you only want to get 0.8-0.84% carbon back into solution. If you go hotter than 1475, you will put more carbon into solution, get larger carbides, and need a sub zero treatment to get rid of retained austentite. This is fine for industrial applications such as bearings, but not what you want in a knife.
 
Willie71 said:
Austentizing a hypereuctoid steel above 1475f is going to result in retained austentite. Once normalized and cycled, you only want to get 0.8-0.84% carbon back into solution. If you go hotter than 1475, you will put more carbon into solution, get larger carbides, and need a sub zero treatment to get rid of retained austentite. This is fine for industrial applications such as bearings, but not what you want in a knife.
Click to expand...

Not questioning you on this but why use 52100 then. Wouldn't it then be equivalent to 1084 basically? Would dry ice get rid of RA?


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kuraki said:
I follow AKS's recipe for hardening. Normalizing aside, I heated to 1600F for 5 min and quenched in oil, tempered at 400F and got 60-61 RC. They give an austentizing range of 1545-1615F and I generally use the higher end of the range they provide because of my furnaces heat zones, I get the called temperature near my thermo probe and lower temperature as I move away from it, so calling to the high end of the ranges specified generally gives me the most consistent results.
Click to expand...

Those numbers are off the Bohler charts. I don't understand them, and none of the other charts I have seen use such a high austenitization. I suggest you use 1475-1500F.

Carter:
There is nothing basically wrong with your regime. I would drop the hold times to 10 minutes, and make the austenitization at 1475F. Stuart's tweaks do pretty much the same.
If the blade was forged, I would do the repeated quenches to refine the grain. If it was just ground from stock, I would just cool to black each cycle.
Like Stuart, I would suggest 425F tempering for a slicer and 450F for a field use knife.

Natlek:
The hold times on steels with alloying is to allow the alloying and carbon to get properly distributed before hardening. The normal hold is 10 minutes, but 5 minutes should be the minimum for any steel but 1084. This is especially important om hypereutectoid steels.
 
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Stacy E. Apelt - Bladesmith said:
Those numbers are of the Bohler charts. I don't understand them, and none of the other charts I have seen use such a high austenitization. I suggest you use 1475-1500F.

Carter:
There is nothing basically wrong with your regime. I would drop the hold times to 10 minutes, and make the austenitization at 1475F. Stuart's tweaks do pretty much the same.
If the blade was forged, I would do the repeated quenches to refine the grain. If it was just ground from stock, I would just cool to black each cycle.
Like Stuart, I would suggest 425F tempering for a slicer and 450F for a field use knife.

Natlek:
The hold times on steels with alloying is to allow the alloying and carbon to get properly distributed before hardening. The normal hold is 10 minutes, but 5 minutes should be the minimum for any steel but 1084. This is especially important om hypereutectoid steels.
Click to expand...

I tried that initially and got poor results but even though I'd read Willie's linked thread in the sticky section, I didn't follow that normalizing procedure first. I'm guessing he's right that I got hard but with a large grain. I intend to break some of the tang from one of those knives tonight and see. I haven't finished them yet so I can redo, thankfully.

Thank you both for the advice. I need to start a spreadsheet.
 
Ghostman3 said:
Not questioning you on this but why use 52100 then. Wouldn't it then be equivalent to 1084 basically? Would dry ice get rid of RA?


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Click to expand...

No, the carbides are set up in the previous steps. You don't get everything back into solution and mess it all up after refining everything in the previous steps.
 
Willie71 said:
No, the carbides are set up in the previous steps. You don't get everything back into solution and mess it all up after refining everything in the previous steps.
Click to expand...

Would this also apply to any hypereuctoid (spelling?)steels?


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Quenching at 1650F is a bad idea. You are risking cracks.

This seems to work for me.
After forging or before stock removal...
1650F-1700F, 5 mins, let cool to magnetic
1525F-1550F, 5 mins, let cool to magnetic.
1475F, 5 mins, quench in oil.
1250F-1300F(still magnetic), no hold, 2-3 times
After grinding...
1250F stress relieve, 2-3 mins, check for straightness.
1475F, 5 Mins, quench in oil
400F-450F, 2hrs, twice (hardness to suit intended purpose.)

You want to set up those carbides, initially. Then bring it back up to the minimum austenitizing temperature for a short soak to distribute the remaining carbon without undoing what you've previously done.
 
Ghostman3 said:
Would this also apply to any hypereuctoid (spelling?)steels?


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Click to expand...

Outside of weird alloys, yes.

You need to test each steel type for the optimum temperature based on the alloying. 52100 likes 1475 in my shop, while W2 likes 1460.
 
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Carterwhopkins said:
Thanks Rick....what is the purpose of the heating prior to initial grinding?
Click to expand...

Because the last normalization cycle ended with a quench, leaving it fully hardened. The few subcritical heat cycles temper out most of the hardness, without fully spheroidizing.

Or, maybe you are asking why I would normalize prior to stock removal? Most of the steel you get from suppliers like Aldo come highly spheroidized. Other than that, there was not much attention paid to grain refinement and uniformity. I'm not saying it definitely isn't uniform, but I choose to start with a clean slate. for the sake of consistency. Normalizing breaks up those spheroids and distributes carbon throughout the matrix. You can do it after you grind to shape, but why? With a uniform stock thickness, you are more likely to avoid hot spots, warping and decarb/scale messing with your finish.
 
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Thanks Rick.....the second part of your answer is what I was asking....will definitely give it a try next time.
 
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