Sandvik Blade Steels

K

KenH

Well-Known Member
I’ll attempt to present some information on Sandvik’s alloys that are most recommended on the Sandvik site for knife blades. 12C27 and 14C28 (sometimes shown as 12C28N) are the only two I have used and I have been impressed with these. Most all this info is paraphrased from the Sandvik website, with some from personal observations and discussion with John Foster, a Sandvik technical engineer. Below is the chemical composition of 4 popular alloys. Remember, per Sandvik website: “The most important thing to remember is that hardness and corrosion resistance are related to the composition of the matrix after hardening, not the nominal chemical composition of the steel. “

Sandvik AlloyCarbon %Silicon %Manganese %Phosphorus %Sulfur %Chromium %Nitrogen %
12C270.60.40.4N/AN/A13.5N/A
12C27M0.520.40.6N/AN/A14.5N/A
13C260.680.400.60N/AN/A12.9N/A
14C28N0.620.20.60.0250.010140.11

Sandvik 12C27 is Sandvik’s old standby for knife steel, and has been in use for almost 50 years. It is the main steel used for knives. The current 12C27 alloy is much different and MUCH improved compared to the 1960’s era alloy due to the carbide microstructure which allows a very sharp and tough blade. While 12C27 has been Sandvik’s recommended steel for knives in the past, a new alloy 14C28 is the new alloy and I expect will become the recommended steel alloy since it has better corrosion resistance and a tad more hardness with the same toughness as 12C27. I find it interesting Sandvik chose to keep the same 12C27 designation for the steel rather than a different designation for the improved alloy. I was not able to find the chemical composition for the 1960's 12C27 alloy, so I'm not sure if the change is due to composition change, or better control of the process with modern technology.

The small size of the primary carbides gives Sandvik a decent microstructure. The maximum carbide size of Sandvik steels is 2 microns, with the average size being 0.5 microns. Per Sandvik, this is even smaller than some of the Powder steels. Take a look at this webpage for a good discussion of Sandvik’s microstructure:
www.alleima.com

Hardening programs for Alleima knife steels

Hardening programs carefully matched to the various Alleima steel grades and to different furnace types to suit either individual pieces of knife blades or an entire batch.
www.alleima.com www.alleima.com

In depth single piece heat treating information is provided on the Sandvik website for each of the alloys in 3 different types: no freezing, home deep freeze at -5º, and cyro-freezing at -95º, only leave piece in cold long enough to reach listed temperature. The heating soak time is the same for all alloys listed above, with only time for center of piece to stabilize at required temperature. Soak time is 5 minutes for 0.100” thick, 6 minute for 0.118, ranging up to 12 minutes for a 0.157” blade. The Quench should be as rapid as possible with maximum time is for piece to drop to 1100Fº in less than 2 minutes. This allows a profiled blade to be beveled before heat quenching and still have the edge properly hardened.

12C27 temperatures for single piece heat treating:
Method12C2712C27M13C2614C28N
No Freezing1975ºF1975ºF1940ºF1920ºF
-5º Freeze1995ºF1995ºFN/A1940ºF
-95º Freeze1995ºFN/A1995ºF1975ºF

Freezing requires only time for material to reach desired temperature – I usually leave in freezer for an hour, bring to room temperature, then to tempering oven for 2 hours. Per the John Foster (Sandvik technical engineer) there is no advantage to tempering multiple times.

Comparing the table above to Sandvik datasheets, and different places on the website, I found a range of temperatures for the same alloy. From examining the table above the temperature difference for 12C27 and 12C27M is within the accuracy range of most ovens. John Foster said the temperatures in Sandvik's "Hardening Programs" section of website are the most current, that is where the temperatures listed in table above are from.

Below are tempering temperatures and resulting Rockwell hardness expected. The blades I’ve heat treated conform very close to published results.

12C27 single piece tempering temperatures:
Temper TempNo Freeze-5ºF Freeze-95ºF Freeze
345ºF596061
435ºF575859
660ºF545656

14C28N single piece tempering temperatures:
Temper TempNo Freeze-5ºF Freeze-95ºF Freeze
345ºF596062
435ºF575859
660ºF555657

From the tables above you might think 12C27 and 14C28N were almost the same, and they are - except Sandvik says the newer 14C28N has better corrosion resistance and should be a bit tougher making for a better blade.

[edited to add Aug 4th, 2014] From a VERY good authority, paraphrasing a bit: "to make folder back-springs, heat treat as normal, except temper the 14C28N at 1040 for two hours. That will get about 45 Rc without a sub zero quench, 46 -47 with a sub zero quench. A sub zero is -5ºF , no need for a long soak. You can do this in your home freezer. 14C28N makes an excellent spring if tempered correctly". I'm sure 12C27 would also.

Any typos in the above are my own typos. Any changes, comments or corrections are welcome.

Ken H>
 
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I hear the 14C28 is a great cutlery steel. I haven't tried it yet. I have been using AEB-L with great results and basically the same heat treat as described above.

Sent from my SPH-L710 using Tapatalk
 
Hey Ken...yes, I'm alive..., sorta, only half dead feeling, that's all!
I just wanted to thank you for putting this on here, I just thought how funny it was
that I introduced you to 12C27 and now you just introduced me to 14C28!
From the HT info there, it looks to me that it will be better for me with my kiln,
I really hated taking my kiln to 1990, I think it was, I'd have to check my notes before I
quote myself for sure, my kiln isn't rated above 2000 degrees so to keep it working and
NOT in a puddle of brick and steel, the 1920 degrees looks way better and no freeze treatment, even better! Have you looked into the cost of that steel? Just curious, I can look it up, I was seriously Impressed with the 12C27, for the cost to performance ratio, it blew me away! And it's a stainless or should I say stain resistant, to be proper. Still a screaming deal for really great steel, what little I've been able to get to the shop here lately, I have only been working on my slip joint project! Gimme a call and I'll fill ya in, basically everything worked out just like you said it would, which is exactly what I thought would happen, anyway other than that, I've got that huge bar of CruForgeV, like 1.5" thick I think, I'd have to measure it, it is probably smaller than that, just seems like it is humongous! I'm gonna order a piece of that same steel in bar form, its taking forever to forge this round bar out flat, just so I can got something made out of it, do some tests, for my own research(that means curiousities). I just have to know what it is capable of, and what it's not capable of! I seriously think it has the ability to perform better than 5160 as a forging steel!
Only if I'm capable of doing a couple of things, the main one to me is for it to be able to get a Hamon on it, you know I'm about as Hamon crazy as I am Burl Crazy! It's an even tie, just one cost me more than the other!
Anyway, thanks for the info it is gonna be put to use, on the next stainless knife I have to make!
Talk to you soon, Rex
BTW, as far as I know BLADE is a go! I still need to make reservations in a hotel, I usually stay either at the Hampton Inn, or another I can't remember the name of. Either will be fine, we will probably drive up Friday night and do the show on Saturday spend the night and go home unless there is something lefy at the show for Sunday.
 
Good to hear from you Rex - I came right thru Montgomery last night, but it was just a tad late for visiting and I was needing to get on home.... still a long drive. Maybe my next trip up home I'll be able to swing by for a visit.

I tend to buy from either http://www.alphaknifesupply.com/bladematerials.htm or http://www.admiralsteel.com/shop/ for Sandvik steels. Cost of either the 13C27 or 14C28 is around $8 to $10 for a chef sized blade from either place. Shipping is perhaps a bit more from Admiral, but they only sell 6 ft sections while from Alpha you can get 12" lengths.

Looking forward to Blade this June -

Ken H>
 
KenH said:
14C28N single piece tempering temperatures:
Temper Temp
No Freeze
-5ºF Freeze
-95ºF Freeze
345ºF
59
60
62
435ºF
57
58
59
660ºF
55
56
57
Ken H>
Click to expand...

Ken, reviving an old thread to ask a question. I was going to heat treat a 14C28N blade this weekend, but just never had time to get it done. I found a grocery store here that sells dry ice, so I thought I might try the cryo. My question is, what's the difference between a "no freeze" 59 rc temper and "-95 freeze" 59 rc temper?

If both knives are tempered at a hardness of 59, would there be any performance difference? Guess, I'm asking, if they ended up the same, why mess with the cryo? Might try again to get it done this coming weekend.

Anthony
 
Anthony - freeze or no freeze is a question I've been reading for a long time with still no "solid" answer. For the SS steels most folks say it is better. The idea is that at the same Rc hardness, the steel is somehow tougher. For 14C28N perhaps this is because of the ability to temper at a 435F and get the same 59 Rc hardness as tempering at 345F. I don't know the answer, unless it's the idea the higher the tempering temperature, the less brittle and more tough the steel is.

In talking with the Sandvik engineer about the steels, his indication was -95F freeze did give a tad better blade, but -5F works pretty good and even a no freeze will provide a good blade. Myself, and others I know that use 14C28N only use the -5F freeze since that can be handled in a home freezer. The first time I used a Sandvik steel, I was very impressed with how easy it was to sharpen to a shaving edge. Of course, 440C is the only other SS I have experience with.

Ken H>
 
KenH said:
Anthony - freeze or no freeze is a question I've been reading for a long time with still no "solid" answer. For the SS steels most folks say it is better. The idea is that at the same Rc hardness, the steel is somehow tougher. For 14C28N perhaps this is because of the ability to temper at a 435F and get the same 59 Rc hardness as tempering at 345F. I don't know the answer, unless it's the idea the higher the tempering temperature, the less brittle and more tough the steel is.

In talking with the Sandvik engineer about the steels, his indication was -95F freeze did give a tad better blade, but -5F works pretty good and even a no freeze will provide a good blade. Myself, and others I know that use 14C28N only use the -5F freeze since that can be handled in a home freezer. The first time I used a Sandvik steel, I was very impressed with how easy it was to sharpen to a shaving edge. Of course, 440C is the only other SS I have experience with.

Ken H>
Click to expand...
I wonder the same thing but haven't found a definitive answer. I wonder if Kevin Cashen would way in on the subject.
 
I surely would enjoy Kevin talking about the subject, but it seems like Kevin is focused on high carbon steels. I follow his writings on high carbon. Not sure he will comment on SS, but I sure would like for him to.

Ken H>
 
I would certainly defer to Kevin, but I think this is all about martensite finish temperature. Mf on stainless steels is well below zero F, in many cases a few hundred degrees below 0 degrees F. The liquid nitro bath ensures that 100%, theoretically, of all austenite is converted over to martensite. The simple carbons steels have an Mf of a hundred degrees, or couple hundred degrees.....so there is no gain in cryo treating these simple carbon steels. But because stainless steels have an Mf of well below 0, we cryo them to convert as much over to martensite as we can.
 
samuraistuart said:
......... them to convert as much over to martensite as we can.
Click to expand...

I agree, that's pretty much what I had read. Seemed to me, the cryo might be good if you were going to leave the blade hard, since you can get an extra point or two out of it, but if you're shooting for 59 rc, you can achieve that anyway. It would be nice if there were any measurable performance differences we could see. Thanks Ken, for answering, I thought maybe I was asking a dumb question, but apparently this is a cloudy topic.
 
chevytrucking said:
I agree, that's pretty much what I had read. Seemed to me, the cryo might be good if you were going to leave the blade hard, since you can get an extra point or two out of it, but if you're shooting for 59 rc, you can achieve that anyway. It would be nice if there were any measurable performance differences we could see. Thanks Ken, for answering, I thought maybe I was asking a dumb question, but apparently this is a cloudy topic.
Click to expand...

The other problem is that the retained austenite will gradually convert to brittle untempered martensite over time (after you've finished tempering).
 
Does the company making these special knife alloys of Stainless Steel have "any" control over how the alloy handles austenite or martensite during tempering and HT'ing? With these special manuf'ing techniques, it seems like they would have some control.

Talking with the Sandvik engineer, he said there was no advantage at all to taking to the liquid Nitrogen level, that dry ice was low enough for max advantage, and that -5F would provide some advantage over no freeze.

I KNOW I do not have the knowledge or experience to make solid statements. I can only repeat what folks with the knowledge like Kevin and the Sandvik engineer say.

Ken H>
 
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Sandvick has made some great steels for knife making use! I'm saying also try M390, Elmax, (if you can get the right size) and that old but once again being much promoter ABE-L Frank
 
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