Custom Knife Blade Steel - A short introduction into the world of knife steels. April 29 2014, 0 Comments
There are more steels used for knives than listed here, we just touch the most common ones.
Steel, the heart of a knife
Generally there are 2 different steels used for knives, carbon steel and stainless steel. The fancy and highly prized version, Damascus Steel, comes in both varieties, Carbon Steel Damascus and Stainless Steel Damascus. Damascus Steel in itself is a big subject and the individual looking to achieve a knife in this steel quality should undergo an extensive research in order to be satisfied.
The basic knife steel with very good edge holding capabilities and a very fine grain in the steel is the carbon steel. Unfortunately this steel will rust, so you have to take special care of your knife, clean and oil the blade after each use and be very careful to store your knife in a leather sheath. Nevertheless, the steel will color.
Some Carbon Steel Knives have a surface coating to prevent the rust. This coating is usually Teflon based and black in the color, a common feature on tactical folders right now.
Carbon Steels used for knives: O1, O2, O6, A-2, L6 (band saw steel), W-1 (spring steel), W-2 (tool steel), 1095 (high carbon steel), 52100 (ball bearing steel), 5160 (another spring steel)
All these steel have a relatively high content of Carbon and are usually very tough.
D2 (planer blade steel) We would like to add to this category the very well known D2. This is a very high carbon steel with a substantial amount of Chrome in it. It actually classifies as a semi stainless steel as it will rust and is especially subject to pit corrosion if not taken care off properly. This is the steel used for planer blades, a knife steel commonly used by knife makers using discarded planer blades.
The modern knife steel is stainless steel. The advantage of rust resistance and relatively low care for the knife makes it the today’s choice for knives. Basic Stainless Steels have a fairly coarse grain which results in less edge holding capability and less toughness of the steel. Nevertheless the advantage of easy care makes it the choice for modern knives, especially kitchen knives and cutlery. To qualify as a stainless steel there should be a minimum of 14% Chromium in the steel as this gives the rust resistance.
However modern high grade stainless steels have finer grain and with the addition of Vanadium and other additives result in good toughness, rivaling the good old fashioned carbon steel. The highest grade of stainless steels is the PM (powder metallurgical) Stainless Steel which is created in a highly sophisticated production process.
Stainless Steel used for knives: 420 (every knife classified as ‘stainless’ is usually 420) also known as AUS-4 and 4A.
This is the classic cutlery steel, medium edge holding capability, easy re-sharpening. Most kitchen knives are made of this steel, a steel widely used by Asian manufacturers. It is also know as Solinger Stahl. 440 group, AUS or A (AUS and A usually refer to a Japanese manufacturer of the steel). Steels of this group have different names depending on the country of origin and the manufacturer. They are fairly similar in their Carbon and Chromium content but vary in the additions like Vanadium, Molybdenum, Manganese, Nickel, etc. 440 A, 6A, AUS 6 Medium Carbon, high Chromium. A knife marked with 440 stainless steel is usually made out of this steel grade. Chinese manufacturers like to use this steel (marked 440) or the 420 (marked Stainless Steel). 440 B, 8A, AUS 8 More Carbon, high Chromium. The better cutlery steel, commonly used by Cold Steel. 440 C, 10A, AUS 10 High Carbon content, high Chromium. 440C (nick name ‘old faithful’ with some custom knife makers) has a higher Chromium content than 10A and AUS 10. A custom knife maker usually has no lower a grade than 440 C he will use for his knives, some use D2 or modified D2 with a higher Chromium content.
High Grade Stainless Steel for knives (this is where the custom knife maker will come into play): ATS 34 (Japanese), CM 154 (US)
Both have high Carbon + 1% and high Chromium + 14% and are commonly used steels by custom knife makers. High quality knives have been made out of these steel for years by experienced makers. They hold a keen edge, have good toughness and give a nice mirror polished blade.
Powder Metallurgical Stainless Steel, the highest grade in stainless knife steel: RWL 34, CPM 154, CPM S30V, CPM S35VN, CPM S90V, M390, Elmax, etc.
These steels rival the carbon steel in the fine grain, the edge holding capability and the toughness. They are made in a sophisticated process, they are not molten like all the other knife steels but made in the Powder Metallurgical Process.
They vary in their content of Carbon and Chromium but are all considered high in both. The additives like Vanadium, Nickel, Molybdenum, etc. vary also and will give the special characteristic of the steel like high toughness, high wear resistance, etc. Knives made out of these steels require special Heat Treatment usually made by the custom maker himself and often a Cryogenic treatment as well. They combine a supreme edge holding with toughness and will be very corrosion resistant. Manufacturer of production knives and cutlery do not choose these steels as they are fairly complex to deal with and also expensive as a raw material. Nevertheless, they are the choice of the custom knife maker to demonstrate his skills and ability to make a very high grade knife. The user of such a knife will be awarded with beauty and a tool of supreme quality and superb edge holding. Unfortunately as a custom made knife the benefits of cost efficiency of mass production are lost.