Page 136 - WCS - Electrical

WORKSHOP CALCULATION & SCIENCE - CITS

Modern methods used to produce wrought iron in large quantities are the

• puddling process
• aston or Byers process
Steel
This is pure iron. Carbon content is more. Due to excessive carbon it is harder and tougher. Carbon content is
from 0.15 to 1.5%. Besides there are other impurities like sulphur, phosphorous etc. are there which cannot be
separated. This is hardened and tempered by heating it to a definite temperature and cooling it in oil or water.
The following methods are adopted for making different types of steel:

1 Cementation process 2 Crucible process
3 Bassemer process 4 Open hearth process
5 Electro thermo process 6 High frequency process.
Types of steel
Main two types of steel are:

1 Plain steel
2 Alloy steel
1 Plain steel: In this carbon and iron are mixed. Accoring to the percentage of carbon plain steels are
classified as:
A Low carbon steel
B Medium carbon steel
C High carbon steel
A Low carbon steel: It is also called mild steel. In this. the percentage of carbon is from 0.15%to0.25%. Due
to less quantity of carbon is sufficiently soft and tolerates the strain. It can be put in different shapes through
forging and rolling. This is not very hard or strong. This cannot be hardened or tempered by ordinary methods.
Nuts, bolts, rivets, sheets, wires, T-iron and angle iron etc. are made out of it.
B Medium carbon steel: The carbon content is from 0.25% to 0.5%. Due to excess of carbon, it is harder and
tougher than mild steel. The tenacity is more. This can be hardened or tempered. Various things are made
by forging and rolling. This is used for making high tensile tubes, wires, agricultural implements, connecting
rods, cam shafts, spanners, pulleys etc.
C High carbon steel: It has carbon content from 0.5% to 1.5%. It is very hard and wears least. This can be
hardened by heat treatment. This can neither be cast nor rolled. This is very hard and tough. It acquires
permanent magnetic properties. This is used for making pointed tools, springs, pumps, files, cutleries, cold
chisels press die etc.

2 Alloy Steel
When the steel is mixed with other metals like vinoleum, manganese tungsten etc., it is called an alloy steel. Alloy
steel has properties of its ingredients.

Types of Alloy Steel
Two types of alloy steel are:
A Low alloy steel
B High alloy steel
A Low Alloy steel: Besides carbon other metals are in lesser quantity. Its tensile strength is more. The welding
can work on it. This can also be hardened and tempered. It is used in manufacturing various parts of an
aeroplane and cam shaft etc.

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CITS : WCS - Electrical - Exercise 11