1. Steel

2. METALS Types Ferrous metals
Non-Ferrous metals: Wherein iron is not the main constituent (Copper, Aluminum, Zinc and lead etc)

3. Ferrous metals:
iron is the main constituent (Cast iron, wrought iron & different forms of steels)
Ferrous metals ► not directly obtained from iron ores
PIG IRON:
From iron ore ► impure form of metal ► Pig iron
It is the pig iron which further yields “Ferrous metals”
Pig iron is not suitable for any mechanical use unless it is converted into cast iron, wrought iron or steel

4. CAST IRON:
Pig iron ► re melted with limestone and coke and poured into moulds of desired shapes and sizes to get purer product known as cast iron
Carbon content in cast iron varies from 2 to 5%
During re melting of pig iron ► scrap iron may also be added for economy

5. Properties of Cast Iron
It is brittle, non ductile, non malleable and cracks when subjected to shocks
It cannot be magnetized
It does not rust
It is strong in compression but weak in tension & shear
Its melting point is 12000C
Its specific gravity is 7.5
USES
Weak in tension therefore cannot be used in construction
Can be used for parts of pumps, motors, engines etc
Because of corrosion resistance ►can be used for pipes to some extent

6. Properties of Wrought Iron
Wrought iron is very malleable and ductile
Its tensile strength is tons /in2
It is strong in compression but not so strong as steel
It can be easily worked, welded and is tough
Its melting point is 28000F
Wrought iron became pasty and very plastic at red heat and could be easily forged at about 16500F
USES:
Since mild steel has replaced the wrought iron, therefore it is no longer produced in large extent. Still in use for roof sheets, wires and metal ornaments etc

7. STEEL
Steel is an alloy of iron and carbon. Pure iron’s strength remarkably increases when alloyed with carbon. The tensile strength increases with increasing carbon content but the ductility reduces. Steel having its properties because of the presence of carbon alone is called “Plain carbon steel”

8. Low carbon steel or mild steel:
The carbon content does not increases 0.25%
Soft and ductile ► mostly used for construction purpose
Uses ► Sheets, rods, wires, pipes, hammers, chains, shafts etc
Medium-carbon steel :
The carbon content is 0.25 to 0.5 %
Stronger than the mild steel slightly less ductile
Uses ► Shafts, connecting rods and rails etc
High- carbon steel :
Carbon content is above 0.5%
Harder and stronger than mild steel and medium carbon steel
Uses ► Keys, knifes, drills etc

9. Properties of Mild Steel
Ductile and malleable
It corrodes quickly
It can be permanently magnetized
It is tough and more elastic than cast iron and wrought iron and withstands shocks and impacts well
It is equally strong in tension, compression and shear
Its specific gravity is 7.8
It is not much affected by Saline water

10. Properties of High-carbon Steel
Its structure is granular
It is more tough and elastic than mild steel
It is easier to harden and then to weld
It is more difficult to forge and then to weld
It can be permanently magnetized
Comparatively it is stronger in compression than in tension or in shear
It withstands vibration and shocks better

11. MANUFACTURE OF STEEL
Three basic raw materials are needed in large quantities for the production of steel
Iron Ore
Coal
Lime stone
The first step in the steel manufacture begins at the blast furnace. To separate iron from iron ore ► coke (substance when gas is taken out of coal), limestone and dolomite are charged into the blast furnace

12. Temperature raised to 1600oF
Temperature raised to 1600oF. This high temp causes the coke to burn and melt the iron. This red hot iron drained at an opening at the base of the furnace. Natural gas is often injected to reduce the amount of coke consumed. The dolomite and limestone combine with the non-ferrous elements of the ore to form a slag, which floats on the top of the molten iron and is removed separately. The product of the blast furnace is known as “Pig Iron” the basic ingredient of steel

13. It takes 2 tons of iron ore, 2/3 ton of coke, ½ ton of limestone, 4 tons of air to make 1 ton of Pig iron. Some of the pig iron goes to the foundries to make iron castings, but the vast majority is re melted and used in the production of steel in steel furnace. Several types of furnaces are used for the production of steel including
Open Hearth Furnace
Bessemer Furnace
Electric Furnace
New Oxygen Furnace

14. TMT STEEL RODS
Bamboo has been used - for construction activities, later it has been replaced by CTD (Cold Twisted Deformed steel rods) or TOR steel rods.
The manufacturers adopted the “Cold Twisting Process” in which the naturally cooled rods were twisted by means of motors.
Thus the molecular structure of the core steel is weakened.
Now, the TMT (THERMO MECHANICALLY TREATED) steel rods have emerged. This rod is not twisted; instead it is treated with the WATER JACKETING PROCESS and allowed to cool in the ambient condition.

15. COMPOSITION: The TMT chemistry BIS (bUREAU OF INDIAN STANDARDS)
BIS (bUREAU OF INDIAN STANDARDS)
Rosun TMT
Carbon (Max%)
0.30
0.25 to  0.30
Manganese (%)
0.5 to 1.2
0.5 to 0.8
Sulphur & Phosphorous
as per IS:1786/85

16. Advantages of TMT:
 Savings of 14 – 19% steel
Reduction in Costs
Better safety of structures
Easy working at site
Better ductility & bend-ability
Better Corrosion Resistance
Good Weld-ability
Resistant to fire hazards

17. Higher strength with better elongation Excellent Weld-ability
Special Features of TMT Bars:
Higher strength with better elongation
Excellent Weld-ability
Resistance to fire hazards
Excellent Ductility
Higher Fatigue Strength
Easy work – ability at site
Better Bonding Strength
Better Corrosion Resistance
Achieves better results than BIS Standards