Page 137 - WCS - Electrical

WORKSHOP CALCULATION & SCIENCE - CITS

B High Alloy Steel: Besides carbon it has a high percentage of the metals higher than low steel alloy. This is
classified into following types:
a High Speed Steel: It is also called high tungsten alloy steel because it has more quantity of tungsten.
According to the quantity of tungsten it is classified into three types:
1 Tungsten 22%, Chromium 4%, Vanadium 1%
2 Tungsten 18%, Chromium 4%, Vanadium 1%
3 Tungsten 14%, Chromium 4%, Vanadium 1%
Cutting tools are made out of it because it is very hard but becomes soft at low critical temperature. This
temperature is raised out of cutting process of tool, then the cutting tool becomes useless and is unfit for work.
But due to high percentage of tungsten it keeps working upto high temperature. It is used for cutting tools, drills,
cutters, reamers, hacksaw blades etc.
b Nickel Steel: In this 0.3% carbon and 0.25 to 0.35% nickel is pressent. Due to nickel its tensile strength,
elastic limit and hardness is increased. It does not catch rust. Its cutting resistance increases 6 times more
than plain carbon and steel due to 0.35% nickel present in it. This is used for making rivets, pipes, axle
shafting, parts of buses and aeroplanes. If 5% of cobalt is mixed with 30-35% nickel, it becomes invar steel.
It is mainly used for making precious instruments.
c Vanadium Steel: It contains 1.5% carbon 12.5% tungsten, 4.5% chromium, 5% vanadium and 5% cobalt.
Its elastic limit, tensile strength and ductility is more. It has strength to bear sharp jerks. It is mainly used to
manufacture of tools.

d Manganese Steel: It is also called special high alloy steel. It contains 1.6 to 1.9% of manganese and 0.4 to
0.5% carbon. It is hard and less wear. It is not affected by magnet. It is used in grinders and rail points etc.
e Stainless Steel: Along with iron it contains 0.2 to 90.6% carbon, 12 to 18% chromium, 8% nickel and 2%
molybdenum. It is used for making knives, scissors, utensils, parts of aeroplane, wires, pipes and gears etc.
Properties of stainless steel:
1 Higher corrosion resistance
2 Higher cryogenis toughness

3 Higher work hardening rate
4 Higher hot strength
5 Higher ductility
6 Higher strength and hardness
7 More attractive appearance

8 Lower maintenance
f Silicon Steel: It contains 14% of silicon. Its uses are multiferrous according to the percentage of silicon. 0.5%
to 1% silicon, 0.7 to 0.95% manganese mixture is used for construction work. 2.5 to 4% silicon content mixture
is used for manufacturing electric motors, generators, laminations of transformers. In chemical industries 14%
silicon content mixture is used.

g Cobalt Steel: High carbon steel contains 5 to 35% cobalt. Toughness and tenacity is high. It has magnetic
property therefore used to make permanent magnets.

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CITS : WCS - Electrical - Exercise 11