Reheat treating 13C26 to 64+HRC

J

jimmyh

Joined
Mar 11, 2007
Messages
57
I have a kershaw leek with a 13C26 blade that I'd like to get reheat
treated to 64-64.5HRC so I can take advantage of the edge stability of
this steel.

I know someone with the capabilities to do this, but I need a good
recipe for him to follow.

Stealing from Cliff Stamps site, I get what should be Landes's heat
treat

http://www.cutleryscience.com/reviews/blade_materials.html#S_AEBL

* Furnace: Vacuum, protective gas, or salt bath
* Preheat 1: 450-600°C equalize 3-5 min
* Preheat 2: 850-950°C equalize 3-5 min
* Austenize: 1065°C eqalize 3-5min, hold 5min
* Quench: oil preheat to 60°-80°C; N2 4bar
* Cryo 1: immediately after quench min. -70°C or lower, hold 1h
* Temper1: 150°C for 1h, then quench in Water
* Cryo 2: immediately after quench min. -70°C or lower, hold 1h
* Temper 2: 150°-180°C for 1h, then quench in Water

The thing is that he lists the hardness of the steel as 60-63 despite
talking about it working best at 64 other places, and the comments
preceding this heat treat procedure were seemingly contradictory about
the 1050C vs 1065C austenitizing temperature.

Does this look like a good way to get the most edge stability out of
this steel? If not, where do I go to find a better procedure to
follow?

What does he mean when he says "equalize 3-5min, hold 5 min". I
thought that both "equalize" and "hold "meant "put it in the salt
bath"

Thanks,
Jimmy
 
jimmyh said:
What does he mean when he says "equalize 3-5min, hold 5 min". I
thought that both "equalize" and "hold "meant "put it in the salt
bath"

Thanks,
Jimmy
Click to expand...

What it means is that it takes about 3-5 min for the blade to evenly hit the time required and then once it is there it needs to sit at that temp for 5 min to make sure every thing is dissolved in the steel.
 
I've been wondering this myself. I'm not sure what's the rationale for some of the things Landes does in his heat treat, but based on what Sandvik recommends to get to 63 rc, it's:

Austenize: soak 5 minutes at 1080° C, quench in oil, cryo in acetone/dry ice, temper 2 hours at 150° C for a final hardness of 63 hrc. This has been tested by knifemakers. Maybe try a lower temper temperture for 64 hrc.

13c26heattreat.jpg
 
I have never used that steel before, but my .02:

That soak time sounds kinda short to me, but I guess it doesn't have a lot of carbon.
A quench from the temper makes no sense to me, but is probably harmless.
The cryo as a part of the quench sounds correct to me.

Re heat treating complex steel can lead to large grain growth. For example D2 can go from a 9 to a 3 if simply reaustenitized. M2 - same problem. This steel of yours has lower carbon, but still a fair amount of alloying, so I'd worry it may also behave this way, but I don't know.

Cliff Stamp.. Wow, I haven't heard that name in a while. Is he still into knives? Good for him...

Steels like this show an increase in hardenability towards the high end of the recommended austenitization range that begins to decrease as retained austenite becomes a problem. A quick trip into LN for a 6 hour soak after soaking at 2000F might possibly maximize the hardness - but that is just a WAG.

You know - HRC62 will likely display better edge stability than 64. You have to balance edge roll with chipping. I'd temper it at least 350.
 
13C26 does have very high toughness and the temper can be relatively low. Make sure to test for your application and find the sweet spot.
 
jimmyh said:
Stealing from Cliff Stamps site, I get what should be Landes's heat
treat...........


.......What does he mean when he says "equalize 3-5min, hold 5 min". I
thought that both "equalize" and "hold "meant "put it in the salt
bath"

Thanks,
Jimmy
Click to expand...

You probably want to look into it further from other more reliable sources.

From what I understand, although Stamp liked to expound on Landes work, Roman Landes texts are written in German and Stamp does not read, write or speak German...he was kind of going by the pictures.

cotdt said:
I've been wondering this myself. I'm not sure what's the rationale for some of the things Landes does in his heat treat,
Click to expand...

By the way how's your fluency in the German language cotdt? Are you working from a Landes text or second hand?
 
Last edited:
What it means is that it takes about 3-5 min for the blade to evenly hit the time required and then once it is there it needs to sit at that temp for 5 min to make sure every thing is dissolved in the steel.
Click to expand...

Thanks. That was the way I interpreted it, but it doesn't make much sense since they have no idea how long it takes my knife to come to temperature, as it depends on the heating method and thickness. A thin blade in a salt bath should take much less than 3-5 minutes to reach full temperature.

Maybe try a lower temper temperture for 64 hrc.
Click to expand...

After seeing that torsional peak for 1095, I'm hesitant to just 'wing it' and miss the optimum by that much.

Re heat treating complex steel can lead to large grain growth. For example D2 can go from a 9 to a 3 if simply reaustenitized. M2 - same problem. This steel of yours has lower carbon, but still a fair amount of alloying, so I'd worry it may also behave this way, but I don't know.
Click to expand...

Is there an easy way to 'reset' that clock or do they just keep getting bigger and bigger?

Cliff Stamp.. Wow, I haven't heard that name in a while. Is he still into knives? Good for him...

Steels like this show an increase in hardenability towards the high end of the recommended austenitization range that begins to decrease as retained austenite becomes a problem. A quick trip into LN for a 6 hour soak after soaking at 2000F might possibly maximize the hardness - but that is just a WAG.

You know - HRC62 will likely display better edge stability than 64. You have to balance edge roll with chipping. I'd temper it at least 350.
Click to expand...

Haha, I don't know if he's still into knives, but his internet activity on the subject seems to have stopped.

I'd say that harder things are stronger and so that it should only chip after the softer edge had rolled, but then I can't explain that freaky torsional strength peak for 1095. Can you?

You probably want to look into it further from other more reliable sources.

From what I understand, although Stamp liked to expound on Landes work, Roman Landes texts are written in German and Stamp does not read, write or speak German...he was kind of going by the pictures.

cotdt said:
I've been wondering this myself. I'm not sure what's the rationale for some of the things Landes does in his heat treat,

By the way how's your fluency in the German language cotdt? Are you working from a Landes text or second hand?
Click to expand...

It's not that I don't trust that source, it's that I don't know what it even claims.

From what I understand, Stamp did exchange a few emails with Landes on the subject though.

I read a thread where one member (STR?) was praising a 64.5HRC 13C26 leek he got from kershaw, and I'm sorta surprised there hasn't been more interest in something like this. I'd ask Thomas W. on the Kershaw forum what they did but...
Click to expand...
 
Well the 150° C tempering temperture has been tested, and it should get you 63 rc. Maybe higher, I don't know, you would have to do hardness measurements. There's no data on toughness vs. hardness for this steel, we will have to be the pioneers.

Rehardening steels are fine, you just have to take more steps to avoid grain growth. You can't just treat it like annealled steel.

Regarding toughness peaks for 1095/A2/D2/etc. there is a certain tempering temperture that leads to tempered martensite embrittlement (TME) and either above or below this temperture is fine. At this tempering temp though, it leads to carbide precipitation which gives pathways to form cracks. I don't know if it exists in 13C26.
 
I didn't want to get into this thread since the name C Stamp was mentioned.
However 13C26 has only .70 C .My notes [ don't remember where they come from ]mentions 63 HRc ,this of course with cryo .This seems more reasonable to me.
 
Some did do it and I have two of the blades and use one. It was cryo used to achieve that hardness in the end but it was hard to duplicate and the retained austentite was quite high which was never really dealt with to satisfactory levels. Although the blade I have performs quite well and pleases me to no end with how well it maintains a good apex for cutting performance the 27% retained austentite from what I was told made it very hard to justify really doing a lot of it. From my point of view its apparent that even with that much retained it can still perform but the question I guess is do you want that much? I really don't know the ins and outs nor do I want to get into a lot of discussion about this again but thats what I recall from some that Kershaw did experimenting with that steel when they first began using it.

STR
 
I came across a write-up by C.S. and somebody else where they described the testing process and results of testing a number of knives. Right at the beginning it was revealed that the L6 blade was way low in RC hardness, like 50 or so but they continued to test the blade and continued to note how poorly the L6 blade was performing - seemingly without a clue that it was poorly HT'd.

So, I'd take anything with a grain of salt.
 
I didn't want to get into this thread since the name C Stamp was mentioned.
Click to expand...

How old are you? Should we modify Godwins law and correlary for blade forums to mention Cliff Stamp instead of Hitler?

Just because the information passed through Cliff Stamp doesn't make it wrong or evil. Stamp cannot make the sky green by stating that it's blue. Additionally, upon hearing him declare the sky to be blue, one can still have conversations about the blueness of the sky. Don't let someone spoil your fun like that.

Whether or not you like the guy, he presented someones heat treatment procedure that I might want to use.

nor do I want to get into a lot of discussion about this again
Click to expand...

It's bad enough that people can't talk politics/religion without getting their upset, but heat treating? If it helps, we can not mention the "K" word.

Hardheart: thanks for pointing me to that thread. I had not found that one.

STR, does the retained austentite issue mean that perhaps 63HRC would be better anyway?

Cotdt/Hanson: As making a blade is more work than I'm willing to do, what extra steps do I need to do in order to reheat treat this thing without having large grains?
 
Cotdt/Hanson: As making a blade is more work than I'm willing to do, what extra steps do I need to do in order to reheat treat this thing without having large grains?
Click to expand...

You will need to follow the proper annealing procedure, with a digitally controlled oven. I don't know it myself but I'm sure it's out there.
 
The temperatures given out in the literature for heat treating 13C26 are on the low side. Sandvik literature talked about using 2050F when oil/cryo is used. This will dissolve more carbon and chromium into the austenitic matrix for higher hardness and improved corrosion resistance. The 2050F austenization and a 325F temper should reach 63+ rc, I don't know about 64.

I did several 13C26/AEB-L knives at a slightly lower temperature (1995F) held 20 minutes but the 325F temper works (ie. passed chipping tests). Oil quench and straight to the LN2, then triple-temper 2 hours each at 325F in a calibrated toaster oven.

I re-hardened the OP's Kershaw Leek with excellent preliminary results. Edge stability (resistance to edge deformation at thin angles) on the rehardened ~63 rc blade is excellent. No chipping or rolling at 22° inclusive when it came to whittling wood and batoning through drywall. The knife is being used as a straight razor now for my daily shaving, now at 17° inclusive. It still shaved after cutting 250 ft. of cardboard, but I ran out of cardboard to test.

Note the black coating is discoloration from the heat treat, the original DLC coating did not survive all that time in the oven.

leek63rc.jpg
 
250 inches in one spot and still shaving hair at that spot is very good. :thumbup:
 
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