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12c27 questions

R

running bird

Joined
Sep 29, 2015
Messages
490
I figured this would be the best stop to post this. Please correct me if I'm in the wrong spot.

One of my favorite steels is 12c27 and I know it perform fairly well at the average 58rc that most major companies temper to. I was wondering if there are any custom makers are able to harden it past 58rc with a cryo treatment ( do big knife companies even do this?)

How much does the performance change at say 59rc or 60rc? I would assume it would hold its edge a lot better and would perform very well. Is this correct or would it become way too brittle? The idea of a very fine grained steel with a higher hardness just seems like it would be perfect (at least to me).

Thanks for any information on the topic,
Kevin
 
I'm not sure the difference in HRC but I can attest that the 12c27 used in newer Sanrenmu knives is fantastic at the super low price point. My 7071 takes a razor edge quickly, and I can see in the bevel how fine the grain is. It holds a solid edge for longer than I expected. I turned a full size couch into small pieces for disposal with mine. Fabric, ropes, plastics all sliced and it was still sharp enough to keep going! I'm interested in the higher HRC as well.
 
Have a few folders in 12c27; one Boker Plus City Tool (single blade), and utility/camper (don't recall which maker) and a couple others - IMHO it is one of the best stainless around.

Rich
 
I believe Mora uses Sandvik 12c27 in most of its stainless blades. According to Sandvik, "Sandvik 12C27 is Sandvik's most well-rounded knife steel with excellent edge performance allowing razor sharpness, high hardness, exceptional toughness and good corrosion resistance. Sandvik 12C27 is our main knife steel for hand-held knives, high-end ice skate blades and ice drills. Continuous improvement over a period of 45 years has evolved Sandvik 12C27 into the high performing steel grade it is today. The composition is tighter, the purity level is much higher and the fine carbide microstructure of today is far from how Sandvik 12C27 knife steel of the sixties looked. With a hardness range of 54-61 HRC, high toughness, scary sharpness and good corrosion resistance, Sandvik 12C27 is the recommended grade for hunting knives, pocket knives, camping knives, high-end chef's knives and tactical knives." Good stuff, in other words.
 
I looked around a bit and found some HT charts from sandvik on 12c27. They show that when tempered to just under 300F you get a HRC of 60. It also showed that tempering to 350F gets you 58rc. I'm assuming tempering at ~300F or tempering at 350F then doing a cryo would both get you the same result of about 60rc. Do any custom makers do this? How much would a couple extra points on the HRC scale really effect the performance?

most of my knives are 12c27 so I'm aware of how it performs, but these knives have a rather average hardness. I was mostly wondering how far 12c27 could be pushed during HT and if that would even improve performance. I would assume most companies temper to 58 to make there knives as durrable as possible.
 
If you can see the grain in the edge bevel, it's not very fine. Look into 13c26 and AEB-L.
 
ya cant see the grain in the bevel. Needs a microscope, polish and etching.

if ya want more hardness look into the steels that me2 suggested, which can push hrc in the low 60s with an immediate cryo after quenching.

there are some custom kitchen knife makers using this steel at high hardness.

but it is not something you find in the production world.
 
I misspoke in my earlier post. What I was trying to say was that the edge bevel looks smooth and consistent. On some cheap knives you can see the edge is crappy looking when starting on the lower grit stones. Not sure if that makes sense to anyone else.
 
I have had Scandinavian knives and a chefs knife in 12c27, they took a great edge,but don't hold exceptionally well.
I like it.


Russ
 
I can't answer your questions sorry, but I love 12c27, it's tough and easy to sharpen.
 
Takes a wicked sharp sharp edge, fairly easy compared to other stainlesses, but one of the bread & butters to 12c27 (and 12c27mod's that many scandanavian companies use) is that it affords very good toughness for a stainless, and that is probably a big factor in as to why it is typically run around that 58 hardness level.

More hardening, in theory, would compromise toughness (for "better" edge holding), but with it being such a simple stainless alloy, as it is basically just carbon and chromium, (another huge benefit to it is that it is a very pure/clean alloy, and the other elements present are more for deoxidizing and purifying the alloy moreso then any other benefit), and also such a low carbon content (between .5 - .6 depending on mod or not), I'm not sure you would get much if any benefit trying to harden it past 58, since carbon is typically the main ingradient in hardening steel, and even the other hardening elements aren't present.

If you want something harder, your best bet is another alloy, 14c28n is a good one, slightly higher carbon (.62) + Nitrogen which acts as carbon in the process, makes it harden up to & just past 60. Still takes a wicked edge and is still pretty tough.
*(14c was specifically designed for knives as an "improvement" over 12c in terms of edge holding).
 
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In my experience, few makers harden 12C27 close to its full potential. I believe most people would be surprised if they had 12C27 at HRC 61.
 
DeadboxHero said:
ya cant see the grain in the bevel. Needs a microscope, polish and etching.

if ya want more hardness look into the steels that me2 suggested, which can push hrc in the low 60s with an immediate cryo after quenching.

there are some custom kitchen knife makers using this steel at high hardness.

but it is not something you find in the production world.
Click to expand...

thats The way:thumbup:
 
12C27 is one of the best, most balanced stainlesses out there IMHO, taking into account cost, corrosion resistance, toughness, ease of resharpening and achievable edge fineness.

The carbides in correctly heat treated 12C27 are in the order of 0.5 microns in diameter.

Remember, one of the reasons why it's hardened to the 57-59 HRc band, is because Sandvik have designed it to roll in preference to chipping when it's pushed past its limits. This is based on the sound reasoning that it's far easier to restore and resharpen a rolled edge than it is to repair a chip. It took me a while and a lot of sharpening many different steels to fully appreciate this.
 
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Cambertree said:
12C27 is one of the best, most balanced stainlesses out there IMHO, taking into account cost, corrosion resistance, toughness, ease of resharpening and achievable edge fineness.

The carbides in correctly heat treated 12C27 are in the order of 0.5 microns in diameter.

Remember, one of the reasons why it's hardened to the 57-59 HRc band, is because Sandvik have designed it to roll in preference to chipping when it's pushed past its limits. This is based on the sound reasoning that it's far easier to restore and resharpen a rolled edge than it is to repair a chip. It took me a while and a lot of sharpening many different steels to fully appreciate this.
Click to expand...

That is true. But you reduce the edge performance for that feature. I'd rather have more performance and it won't chip because I am using it inappropriately. Win win
 
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