Sandvik 12C27, 14C28N and Nitro-V
Sweden does not make knife steel for knives. Sandvik rolls thin strip, and the grades the knife world knows as 12C27 and 13C26 started life as a product for razor blades and industrial tooling. Knifemakers turned out to be a convenient second customer.
The idea: the fewer carbides, the better
The usual logic of knife steel runs like this: more carbon and vanadium — more hard carbides — higher wear resistance and lower toughness. The Swedish school went the other way.
The metallurgists carefully balanced carbon and chromium to get high hardness and corrosion resistance while forming almost no chromium carbides. The carbides stay small, the microstructure very fine, the toughness high. The price is wear resistance: such steels dull faster than powder stainless grades.
The best examples of this approach are AEB-L, 12C27 and 14C28N. Not the most fashionable letters on a blade, and probably the most underrated idea in knife metallurgy.
12C27
A Swedish stainless used for razors for many years. It takes a very keen edge and holds it decently. The honest verdict sounds boring: an excellent steel, but nothing special. That is not a complaint, it is a description.
13C26 and AEB-L
13C26 is the same 12C27 with less chromium and more carbon. It is practically identical to AEB-L: the difference is slightly less manganese and one extra hundredth of a percent of sulphur. Two names, one metal, different mills.
AEB-L is a very clean, fine-grained alloy. With good heat treatment the structure comes out so fine that you can see it in both the wear resistance and the edge retention. For kitchen knives it is hardened to 61–62 HRC — so talk of “soft European stainless” has nothing to do with it. Devin Thomas makes kitchen knives from it with very good results.
19C27
A version of 12C27 with higher carbon and manganese. It is hardened to 60–62 HRC depending on the maker: Kagemitsu to 61–62, Suisin to 60. It sharpens very keen and holds an edge well. Both Western and Japanese workshops use it, among them Kagemitsu and Echizen.
14C28N
The same principle, but with nitrogen. A nitrogen atom in the lattice behaves much like a carbon atom and does less damage to corrosion resistance. Edge retention in 14C28N and AEB-L is relatively low — but still better than in low-alloy steels such as 52100 and 1095, because chromium carbides are harder than cementite.
This is a good occasion to close the “stainless versus carbon” argument. Here the stainless steel has an objectively better balance of properties than the classic carbon steel. The question is always which two steels are being compared and on which property, not which of the two categories is nobler.
Nitro-V
Nitro-V came out in 2017. It is sold by New Jersey Steel Baron and was developed and produced together with Buderus Steel as a version of Uddeholm AEB-L modified with nitrogen and vanadium.
The similarity to AEB-L is literal: the same carbon, the same chromium, the same silicon, a small difference in manganese. There is as much nitrogen as in 14C28N — apparently that is simply the limit of how much can be introduced in ordinary, non-powder steelmaking.
Very little vanadium was added. So little that it most likely has no effect on wear resistance and edge retention at all. Micro-additions like this are usually there to refine the grain, but in high-chromium stainless steels grain refinement takes more vanadium than there is here. The V in the name works less well than it sounds.
The branch next door: niobium
The logical continuation of the Swedish idea is to keep carbides scarce but add a little niobium for wear resistance. Niobium is a stronger carbide former than vanadium and can form carbides of its own even where there is plenty of chromium.
The nearest available steel of this approach is Niolox. It did not turn out quite as intended: its carbides came out relatively coarse, and the toughness was not as high as theory promised. And the largest carbides in it are the chromium ones.
Who it is for
For someone who sharpens his own knives and likes a thin edge: these steels give it easily and do not chip when the angle is taken aggressively low.
Not for someone who wants to break down a crate of pumpkins without going near a stone. The deal here is honest and symmetrical: you get an edge that resists chipping and sharpens easily, and you pay in sharpening frequency.
A separate virtue of these grades is the price. They are cheap and do not require diamond stones. If you own a stone and have two minutes, paying extra for exotic powder stainless in a kitchen knife stops being obvious.