Several elements can be added to steel to produce different traits.  What follows is a list of elements commonly added to knife steel and their purposes.

Carbon: This is the most important element to be added to steel for hardening the steel. Knife steel should have greater than ½ % carbon, which would make it high carbon steel. Carbon steel usually means few or no alloy ingredients have been added. Knife steel with a high carbon content but low chromium content is prone to rusting and pitting if not kept dry and oiled.

Chromium: This is added for hardening, and to increase wear and corrosion resistance. Knife steel with at least 13% chromium is considered stainless steel.

Cobalt: Cobalt is added to knife steel to increase the strength and hardness. It permits quenching at higher temperatures and intensifies the individual effects of other elements in more complex steels.

Copper: Copper is added to increase the corrosion resistance.

Manganese: Manganese is added to knife steel as it aids the grain structure and increases the ability to harden the steel. It also increases the strength and wear resistance. Manganese is present in most cutlery steel.

Molybdenum: This element helps prevent brittleness in knife steel and helps the steel maintain strength at high temperatures. It makes the grain size in the steel smaller which improves the hardness and toughness.  

Nickel: Nickel is put into knife steel to increases the strength, corrosion resistance and toughness of the steel. The term corrosion resistance is used because all steel will eventually corrode if it is not cared for properly.

Nitrogen: Nitrogen can be used in place of carbon in knife steel. The Nitrogen atom works similar to carbon but offers the advantage of corrosion resistance.

Silicon: Contributes to the strength of knife steel.

Tungsten: Tungsten is added to knife steel to improve the strength, toughness and hardenability.

Vanadium: Increases the wear resistance and ability to harden knife steel. Like Molybdenum it makes the grain size in the steel smaller which improves the hardness and toughness of the steel.

There are several types of steels that are commonly used by the major manufacturers to make their knife blades. D-2, 420, 440, 425, AUS. These types of knife steel and others will be discussed in another article.