EFFECT OF CARBON IN STEEL

. effect of carbon on the mechanical properties of steel.

Steel  can be defined as an alloy of carbon and iron, in which carbon is in a combained state. The carbon content is a very important factor to get the desired properties of steel.

Carbon

Carbon is a very important constituent of steel.

The addition of carbon  at varying proportions modifies the characteristics of iron and makes it harder, stronger and of greater use in the engineering industry. Slight variations in the carbon content of steel leads to great differences in the properties of steel. Depending upon the properties they are put to different uses.

At room temparature in the annealed condition plain carbon steel contains three main constituents.

-ferrite

-cementite

-pearlite

Ferrite is a very weak solid solution of carbon and iron with about 0.006% carbon. This is a very soft and ductile constituent. Pearlite contains alternate layers of ferrite and cementite. This laminated structure makes pearlite stronger. As the carbon content increases, the pearlite structure formation is also increased, and, this increases the tensile strength and hardness.

It may be noted in the figure that addition of caform beyond 0.83% cementite will not exist in the combined form but appear around the crystal boundaries. Carbon, existing in this form, reduces the tensile strength and ductility but, however, the hardness continues to in crease even beyond 0.83% of ccarbon.

It may be said that plain carbon steel will have a maximum strength at 0.83% carbon ie when the constituent of steel is fully pearlite.

Addition of carbon beyond 0.83% reduces its strength and ductility. Hardness of plain carbon steel increases proportionately even beyond 0.83% carbon content.

Wrought iron

Is carbon content is less than 0.05. Group is wrought iron. Wrought iron is used for chain for lifting tackle, crane hooks, architectural iron work.

Dead mild steel

Is corbon content is 0.1 to 0.15. Its the group is plain carbon steel. It is used for sheet for pressing out such shapes as motor car body panels. Thin wire, rod and drawn tubes.

Mild steel

Is the carbon content is 0.15 to 0.3. Is the group is plain carbon steel. It is used for general purpose workshop bars, boiler plates, girders.

Medium carbon steel

Carbon content is 0.3 to 0.5 0.5 to 0.8.its the group is plain carbon steel. Is used for crankshaft forgings, axles leaf springs, cold Chisels.

High carbon steel

The corbon content is 0.8 to 1.0 1.0 to 1.2 1.2 to 1.4. Is used coil springs, wod chisels, files, drills, taps and dies, fine edge tools (kinves etc)