Types of steel for kitchen knives
Types of steel for kitchen knives
When you buy a kitchen knife, it is recommended to inform yourself about steel types and choose a steel type that corresponds to your expectations of a knife.
In most of culinary schools in Australia or even in other countries, they teach about knife types but unfortunately, about steel types.
There are literally thousands of types of steel. Among them, the most common are carbon steel, stainless steel. You might heard damascus steel as well. But you don’t know what exactly are they? No prob! I am going to let you know what is what.
Let’s study about types of steel for kitchen knives step by step.
1. Carbon steel (non stainless)
Generally, Carbon steel contains iron, carbon, and small amount of manganese. In addition, cobalt, chromium, molybdenum, nickel, tungsten, vanadium are may added depending on the product and the steel manufacturer.
Carbon steel knife is excellent at cutting, edge retention and hardness, but it is easily rusted. So carbon steel knives are more suitable for professional level than beginners. Need to make sure give a good care in order to keep the best performance.
About steel name, each types of steel has a designation system that gives them a specific number. For example, 1095,1045, 5160, A2, CMP M4, D2, M2, O1, ...
However, in this post I will explain more about Japanese carbon steels. Mostly, Japanese carbon knives are made with Shirogami(aka ‘white paper steel’) or Aogami(aka ‘blue paper steel)
- Shirogami / White paper Steel
Hitachi high carbon steel. Shirogami was named after the paper the manufacturer Hitachi packages steel in. It is a variable of so called White Paper Steel. It's very pure carbon steel. Very popular knife steel for high end Japanese cutlery and especially with Honyaki type blades. Very good edge holding, very high working hardness. This means you can grind it to exceptional sharpness, which it retains for a long time. These blades are particularly suitable for the gentle preparation of foods - but they are prone to oxidation, which means rust.
- Aogami / Blue Paper Steel
Hitachi high carbon steel. Blue Paper Steel is White Paper Steel with the addition of small quantities of chrome and wolfram. A lot of Japanese custom makers use it. Easy to sharpen, even high hardness. Edge holding is just outstanding. Original Japanese knives made from these materials are treated with non-corrosive, food-safe oils (e.g. camellia oil) to prevent oxidation. Blue Paper Steel is better corrosion and chipping resistant than White Paper Steel, although it definitely is not a stainless steel
Blue Paper is made in 3 gradations: #2, #1 and Super. 'number 2' is added with 1.2% carbon. This provides hard (62-63 HRC) knives that can be sharpened razor sharp and still be particularly sturdy.
- Yellow Paper Steel(Kigami)
Better steel compared to SK series, but less quality than Aogami and Shirogami. Used in high end tools and low/mid class kitchen knives.
- SK Steel
Solid performer as a cutlery steel. Low grade, mainly due to impurities. It is used mainly in tools like axes, hammers and some cheap kitchen knives.
2. Stainless steel
When carbon steel is mixed with minimum 13% of chromium, it becomes stainless steel.
It is rust resistant. However, containing chromium reduces the cutting performance. So it’s used as an alloy with manganese, vanadium, molybdenum and tungsten. Most of the kitchen knives that we often see are made of stainless steel these days.
"High Carbon Stainless Steel" normally refers to higher-grade, stainless steel alloys with a certain amount of carbon, and is intended to combine the best attributes of carbon steel and ordinary stainless steel. The high carbon stainless steel blades do not discolour or stain, and maintain a sharp edge for a reasonable time.
Most "high-carbon" stainless blades are made of higher-quality alloys than less-expensive stainless knives, often including amounts of molybdenum, vanadium, cobalt, and other components intended to increase strength, edge-holding, and cutting ability. Almost all of our Stainless steels blades are made of High Carbon Stainless steels.
- SG-2 (Super Gold No.2)
This is more common and popular Powdered High Speed Tool Steel for knife blades. You can taste speechless cutting performance, great edge retention and easy maintenance (resistance for the rust). Made by Takefu steel company. Achieves very high hardness.
One of most popular and very high end Stainless Steel. Sharpness, edge retention and durability. It has vanadium which gives it extra toughness. VG-10 steel holds edge really well, and has excellent anti-rust properties.
It contains 0.95-1.05% of carbon. It's often called as “Cobalt Steel”. VG-10 steel is used for the Damascus blade as well.
This is good basic and common Japanese Stainless steel which makes high hardness, edge retention, strength and rust resistance. Both VG-1 and VG-10 are produced from Takefu Steel Company.
- Gingami No.3(Gin-san)
Fine Japanese Steel Company Hitachi’s special stainless steel which makes similar sharpness, edge retention as Carbon Steel. Gingami No.3 often be used for Japanese Traditional Style knives
- Swedish Stainless Steel
The Pure Stainless Steel material from Sweden, that is well known for excellent knife materials in the world. Selected Swedish steel is easier for making process, heat-treating process, and the quality control. It is said that the stainless steel by Bohler-Uddeholm is superior to the steel by the Sandvik, because of the lowest impurities for sharper and more durable knives.
- Molybdenum Vanadium Stainless Steel
One of common and good standard, stainless steel for the knife blades. We often recommend Molybdenum Steel Kitchen knives for first users and beginning users of Japanese knives because of its characteristics. Ease of re-sharpening, good durability and rust resistance, and reasonable price range.
- 420HC Steel
excellent corrosion resistance, easy to reuse and good edge retention. High carbon version of standard 420 type martensitic stainless steel. High chromium content and combined carbon content provide excellent abrasion resistance and edge retention. This steel should not be confused with standard 420 stainless steel. The 420HC is a good general-purpose knife steel and is generally similar to the 440A.
- 440A, 440B and 440C Steel
most common stainless steels today. The carbon content of this stainless steel rises from A (.75%) to B (.9%) to C (1.2%). The 440C is an exceptionally high grade stainless steel that is hardened to approximately 56-58 Rc and is extremely rigid and has good hardness and edge retention. All three bear the rust well. 440A is the most corrosion resistant and 440C is the least. 440C is superior to ubiquitous and is generally regarded as a general purpose stainless steel which is stronger than ATS-34 and has a high stain resistance but weak edge strength and weak strength. If the knife says "440", it is probably cheaper than 440A. I would like to advertise if the manufacturer used the more expensive 440C. The general feeling is that the 440A is good enough for everyday use, especially heat treatment. 440-B is very solid and 440-C is excellent.
- 425M and 12C27 steel
Those two steels are very similar to 440A. The carbon content of 425M is .5%. The 12C27 is Scandanavian steel, which contains .6% carbon and is finally used in puukkos and Norwegian knives. The 12C27 has a high purity and is said to perform very well when carefully heat treated. At the end of the day, it may be a better choice than 440A and similar steels.
- AUS-6, AUS-8, AUS-10 Steel(aka 6A 8A 10A)
These are Japanese stainless steels, roughly comparable in carbon content to 440A (AUS-6, .65% carbon) and 440B (AUS-8, .75% carbon) and 440C (AUS-10, 1.1% carbon). AUS-6 is used by Al Mar, and is a competitor to low-end steels like 420J. Cold Steel's use of AUS-8 has made it pretty popular, as heat treated by Cold Steel it won't hold an edge like ATS-34, but is a bit softer (and therefore weaker) and tougher. 8A is a competitor of middle-tier steels. AUS-10 has roughly the same carbon content as 440C but with slightly less chromium, so it should be a bit less rust resistant but perhaps a bit tougher than 440C. It competes with higher-end steels, like ATS-34 and above. All 3 steels have some vanadium added (which the 440 series lacks), which will improve wear resistance and refines the grain for both good toughness, and the ability to sharpen to a very keen edge. Many people have reported that they are able to get knives using steels that include vanadium, like 8A, sharper than they can get non-vanadium steels like ATS-34.
- ATS-34 and 154-CM steel
ATS-34 was the hottest high-end stainless in the 1990s. 154-CM is the original American version, but for a long time was not manufactured to the high quality standards knifemakers expect, so knifemakers switched over to ATS-34. CPM is again making high-quality 154-CM, and some companies seeking to stick with American-made products are using it. ATS-34 is a Hitachi product that is very, very similar to 154-CM. Normally hardened to around 60 Rc, it holds an edge very well and is tough enough even at that high hardness. Not as rust resistant as the 400 series above. Many custom makers use ATS-34, and Spyderco (in their high-end knives) and Benchmade are among the production companies that use it.
3. Damascus Steel
Damascus is not a type of steel. It is more like a method that is made by folding two different type of steel several times.
There is a lot of price difference depending on the combination of materials. These days, we can see a lot of damascus knives that usually use stainless steel, especially VG-10 steel. But there is also a damascus knife that uses carbon steel. Of course, it is much more expensive than stainless steel damascus.
Damascus steel is also called Damask steel or folded steel. Traditionally, the aim of making Damascus steel was to improve the characteristics of a piece of steel. A piece of rough steel was welded into a longer piece and then folded and welded onto each other again. By repeating this a few times you obtained a piece of steel consisting of hundreds of layers.
Imperfections in the steel are distributed over the piece of steel, which makes the weak spots disappear. The crystal structure of the steel is also refined by sharpening. This meant swords and knives could be made that are much less prone to breakage.
During the production of Damascus steel the steel is heated in a fire. The steel takes in carbon from the fire and by repeatedly folding the carbon is spread over the whole steel. The carbon makes it possible to harden the steel.
EDGE OF STEEL