The basic components in steel are iron and carbon. Any other element added: nickel, chromium, vanadium, molybdenum, manganese or even nitrogen, enable so-called "alloy" steels to be obtained, that have different properties. In cutlery, the steels mostly used are those called "stainless" and "carbon" steels. Carbon steels were the first to be used because they are the easiest to make, containing simply iron and carbon. The stainless steels used for cutlery belong to the martensitic steel family. They contain mostly carbon and chromium. However, other alloy elements may be included such as molybdenum and vanadium. Carbon possesses such useful properties as hardness, resilience and corrosion resistance. For stainless steel, the properties depend on the elements included in its composition. Chromium mostly contributes to corrosion resistance. Molybdenum also improves corrosion resistance, but in oxidizing situations. In addition it improves mechanical resistance in hot conditions. Vanadium is used in small quantities in martensitic chromium to render them indifferent to overheating. It too increases mechanical resistance in hot conditions. The main characteristics that are required in cutlery are: • Hardness: essential for the cutting quality, reduced wear and less frequent sharpening. • Resilience: this is the degree to which a knife can endure deformation without breaking. A steel with no resilience may be very strong but will break with only a little deformation (it is then termed fragile). On the contrary, a very resilient steel will break only after very considerable deformation. • Rust resistance: this is the ability of the steel not to rust. Carbon steel and martensitic steel have very different characteristics: Sharpening: Carbon steel knives are reputed to cut better than stainless steel knives. It is true that, for an equivalent degree of hardness, carbon steel is easier to sharpen than stainless steel. On the other hand, a stainless steel knife will retain its cutting edge longer than the carbon steel knife that will thus need its edge renewing more often. Maintenance: Stainless steel is far easier to look after and far more hygienic than carbon steel. It is true that it does not rust. The blade of a stainless steel knife does not need to be oiled to avoid rust and stains appearing (under normal conditions for use of a knife). Carbon steel, however, requires very meticulous care. A carbon steel knife is capable of rusting in just a few hours. This can be explained by the lack of chromium, molybdenum and nickel that are the main element that combat corrosion. The only way to prevent a carbon steel rusting is to care for it very meticulously, avoiding all prolonged contact between the blade and water. The blade must also be lubricated regularly. Grades of steel: The main grades of steel used in cutlery can be classified according to three main types: - carbon steels of the XC75 (1.1248) and XC100 (1.1274) type, - common martensitic steels such as X20Cr13 (1.4021) or X46Cr13 (1.4034). The latter has replaced X39Cr13, generally called Z40C13, which is no longer marketed. It can also be found under the commercial name of 12C27. - higher alloy content martensitic steels such as X17CrNi16-2 (1.4057), X90CrMoV18 (1.4112), X38CrMo16 (1.2316), X38CrMoV15 (1.4117) or X50CrMoV15 (1.4116). The latter is often used for the manufacture of forged knives, and this is indeed the case for SABATIER Diamant knives. It is very hard after tempering, but without being too hard (it must be possible to sharpen the knife by hand). It presents good corrosion resistance and is well-adapted to the forging process, and also to milling operations.