Properties of Iron and Steel

Properties of Iron:

Cast Iron: Pig iron is the direct metallic product of a blast furnace while cast iron is prepared from pig iron by remelting pig iron in a cupola furnace. It is the most impure form of Fe and contains the highest % of carbon (2-4.5%) and other impurities like S, Si, p, Mn, etc.

Properties of Cast Iron:

i. % of Carbon is 2-4.5%. Carbon present is partly as free carbon in the form of graphite and partly in the form of iron carbide Fe3C.

ii. Due to the presence of impurities, its m.p is low (1100 – 1250°C).

iii. The molten iron expands on solidification and hence it produces good casting.

iv. Due to high carbon content. It is hard and brittle and therefore, it can’t be easily welded.

v. It possesses very little ductility and it’s not suitable for forging.

Uses of Cast Iron: It is used for small casting, railings, hot water pipes, electric poles, bunsen burner bases, and many other purposes where strain is minimum. Wrought iron and steel are manufactured from cast iron.

Properties of Wrought Iron:

i. It is the purest form of iron and contains a minimum amount of carbon (0.1 – 0.15%).

ii. It is extremely tough and melts at about 1500°C.

iii. It is highly malleable and ductile.

iv. Due to the presence of about 1% slag, it has a fibrous structure and thus can withstand unusual stresses.

v. It can’t be tempered.

Uses of Wrought Iron:
i. For the manufacture of articles that can withstand sudden stresses, such as – Chains, nails, hooks, bolts, etc.

ii. For the manufacture of electromagnets and Agricultural implements.

iii. For making bars and wires.

Properties of Steel:

Iron containing 0.15 – 1.5% C as an alloying element is called steel. It is the most important form of Fe and finds extensive applications. As far as C content is concerned, it is mid-way between cast iron and wrought iron. The greater the % of C, the greater the hardness of steel.

In steel, carbon is mainly present as Fe3C. It is hard and elastic. The properties of steel depend upon its carbon content. Soft steels contain C up to 0.25%, Mild steel contains 0.25 – 0.5% C and hard steel contains 0.05 -1.5% C.

Uses of Steel: Steels are generally used for making machine parts, beams, tools, knives, razors, household utensils, etc. Specific use of steel depends upon the nature of metals added to iron.