 Steel, a range of alloys made from iron, has become the metal of choice for the modern age.Various alloys of steel can be made which offer a wide range of physical and chemical properties desirable for blades.For example, surgical scalpels are often made of stainless steel so that they remain free of rust and largely chemically inert; tool steels are hard and impact resistant (and often expensive as retaining toughness and hardness requires expensive alloying materials, and, being hard, they are difficult to make into their finished shape) and some are designed to resist changes to their physical properties at high temperatures.