Alloying elements are added to basic steels to enhance corrosion resistance, hardness, toughness and processibility.

Carbon is the principal hardener in steel. The more carbon that is added (up to 1.2%), the harder it gets. Higher amounts of carbons create high levels of cementite (Fe3C) and go under various names such as white iron, etc.

Phosphorus and Sulfur are present in all steels, usually as impurities, but they are sometimes added in controlled amounts for easier machining.

Molybdenum is one of the most important additives. Molybdenum adds toughness and increases corrosion resistance to withstand industrial chemicals and solvents and inhibits pitting caused by chlorides. Molybdenum also lengthens the quench time of a steel, so that a good, stress-free martensitic structure can be formed. Molybdenum also inhibits grain growth.

Cobalt scissors come in two types. Forged Steel and Powder or Sintered Metal. The powdered metals give the maximum cobalt benefit, but are VERY susceptible to breaking. Never set or bend a cobalt scissor, unless you enjoy buying a new one. The powder metal cobalt alloy demonstrates outstanding mechanical properties and cutting performance. Powder metal cobalt scissors are usually composed of a 50% Co (Cobalt) - 28.7% Fe (Iron) -20% W (Tungsten) - 1.3% C (Carbon) alloy. These alloys attain an un-tempered maximum value of 66 to 67 Rc. Forged Cobalt tools are much tougher than sintered metals, but seldom have more than 10% cobalt in them, making them softer with Rockwells around 58Rc.

Manganese contributes to strength and hardness. The amount of increase is dependent on the amount of carbon present. The more carbon in a steel, the higher the effect of manganese. Manganese is beneficial for the surface finish of a part, especially if the steel is high in sulfur.

Phosphorus increases strength and hardness, but at the sacrifice of ductility and impact toughness, if added in too great a quantity.

Sulfur is detrimental to surface finish in high quantities, but improves machinability.

Silicon is a principal deoxidizer used in steel making. It also increases strength and hardness.

Chromium protects against corrosion and adds heat resistance. Decreases strength and hardness. Must be at about a 18:1 ratio with carbon, since the carbon can take from the alloy about 17 times its own weight of chromium to form carbides. This chromium in the form of carbides is of little use for resisting corrosion.

Carbon Steel - Steel is considered carbon steel, when no minimum content is specified or required of chromium, molybdenum, vanadium, nickel, tungsten or any other element added. The following elements do not exceed 1.65% manganese, 0.60% silicon, or 0.60% copper.

Vanadium adds toughness and fatigue resistance.

Nickel improves corrosion resistance and toughness. Allows higher chromium alloys to fully harden. Types 414 and 431 are the most corrosive resistant of the martensitic steels.