Major Alloying Elements

Major Alloying Elements
Points : Major Alloying Elements, Definition Definition Although many traces of elements can be found in alloy steel and many alloys are used for making special types of steel, there are 12 major alloying elements of steel. Each of the major alloys greatly changes the mechanical properties of the steel.

Adding the alloying elements to the steel changes the physical properties of the alloy steel. The amount of alloy added varies from as little as 0.0005 percent to as ‘much as 27 percent. More than one alloying element may be used. For example, boron is used many times with nickel, chromium, and molybdenum Boron is less expensive than nickel, chromium, and molybdenum. It produces the same basic results as the more expensive alloying metals (i.e., increases the depth. of hardness by heat treating), but it also increases the strength and toughness of the alloyed steel. Of all the major alloyed elements only cobalt, copper and nickel are added as pure metals.

Stainless steel falls into the category of an alloyed steel, but because the AISI recognizes more than 40 types of stainless steel, a special category has been made classifying stainless steel into three broad divisions based on their predominant crystalline structures; ferrite, martensitic, and austenitic. These three categories of stainless steel describe the different properties which determine the use of the stainless steel. Ferritic stainless steels are non-hardenable and magnetic. Martensitic steel is hardenable by heat treating and is also magnetic. Austenitic stainless steels are extremely tough and ductile in the welded state. Strictly speaking, stainless steel should contain a minimum of 11 percent chromium. Chromium forms a thin, passive, slightly adherent surface layer of chromium oxide that gives the stainless steel its corrosion resistance.