ALLOYING ELEMENTS IN STEEL

Alloying elements are classified according to their faculty in forming carbides, austenite or ferrite, and with a view to the purpose for which they are added to ordinary steels. According to the alloying percentage, every element can impart unique and specific characteristics to the steel. The combination of various elements, as utilized in modern metallurgy, can enhance this effect. However, certain combinations of alloying elements may result in constituents which, far from producing a favorable cumulative effect with regard to a certain property, may counteract each other. The mere presence of alloying elements in steel is but a basic condition for the desired characteristic which can be obtained only by proper processing and heat treatment. The principal effect and influences of alloying and accompanying elements are outlined below.

CARBON ( C)
ALUMINUM ( AL )
ANTIMONY ( Sb )
ARSENIC ( As )
BERYLLIUM ( Be )
BORON ( B )
CALCIUM ( Ca )
CHROMIUM ( Cr )
COBALT ( Co )
COPPER ( Cu )
HYDROGEN ( H )
LEAD ( Pb )
MANGANESE ( Mn )
MOLYBDENUM ( Mo )
NICKEL ( Ni )
NITROGEN ( N )
OXYGEN ( O )
PHOSPHORUS ( P )
SILICON ( Si )
SULFUR ( S )
TIN ( Sn )
VANADIUM ( V )
WOLFRAM ( W = TUNGSTEN Tu )

CARBON ( C)
Carbon is present in all steel and is the principal hardening element, determining the level of hardness or strength attainable by quenching. It raises tensile strength, hardness, resistance to wear and abrasion as the carbon content of steel is increased. It lowers ductility, toughness and machinability. Carbon has a moderate tendency to segregate within the ingot.

ALUMINUM ( AL )
Strongest and most frequently used deoxidiser and degasifier, favors insensibility to aging. Added in small amounts, it helps fine grain formation. Since it combines with nitrogen to form very hard nitride, it is a favorable alloy constituent in nitriding steels. Aluminum - killed steels exhibit a high order of fracture toughness.

ANTIMONY ( Sb )
Harmful to steel, as it generally diminishes toughness.

ARSENIC ( As )
Injurious to steel as it increases temper brittleness, decreases toughness and impairs weldability.

BERYLLIUM ( Be )
Used for precipitation hardening with some sacrifice of toughness. Very susceptible to deoxidization. Strong affinity to sulfur, rarely used for steel alloys.

BORON ( B )
Added in amounts of 0.0005% to 0.03% it significantly increases the harden ability of steel. This effect on harden ability is particularly effective at lower carbon levels. Unlike many other elements baron does not affect the ferrite strength of steel. It can be used to increase the harden ability of steel without sacrificing ductility, formability or machinability of steel in the annealed condition.

CALCIUM ( Ca )
In the silicocalcium combination, it is used for deoxidization. Calcium enhances the non-scaling properties of heat conductor alloys

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