Railway Tracks Welding

1. JOINING OF
RAILWAY TRACKS
BY: SANYAM JAIN(2K20/A10/63)
SHUBHAM KUMAR(2K20/A10/75)

2. R A I LW AY T R A C K S A R E
G E N E R A L LY J O I N E D B Y
T H E R M I T E W E L D I N G .
W H AT I S T H E R M I T E
W E L D I N G ? ? ?

3. THERMITE WELDING
• Thermite welding is a type
of fusion welding process.
• It is also known as
exothermic welding.
• This process is used to
weld a heavy and large
structures.
• It requires no electrodes
and any power supply

4. •In this process , welding is
done by pouring super-
heated liquids around parts
to be joined.
•A short moulding process is
to be done before welding
PRINCIPLE

5. WHAT IS THERMITE ?
• A mixture of fine aluminum powder and iron oxide that
produces a very high temperature on combustion ,used in
welding and for incendiary bombs.
Thermite reaction involving aluminum is also called
Goldschmidt alumino thermic reaction . Usually this
reaction is triggered by burning magnesium ribbon in
presence of Barium peroxide.

6. COMPOSITION OF
THERMITE
•By weight, 75% of iron oxide and 25% of fine
aluminum powder
•Fine aluminum powder and iron oxide should
have a ratio of 1:3 (by weight)
• We can also use copper or chromium instead of
aluminum.

7. STEPS FOR JOINING :
• The ends of parts to be joined are kept parallel with a uniform
gap between them.
• That gap is filled with wax which becomes the pattern.
• Moulding sand is rammed around wax pattern. Pouring gate,
heating gate and risers are cut.
• Joints to be welded are preheated by a flame (external
source). Due to preheat wax melts and goes out.

8. • After melting of wax, weld joints are preheated due to flame.
• Then heating is stopped and heating gate is closed.
• Crucible is placed directly above the joints to be welded.
• After preheating of joints, liquid thermite steel from the
crucible is poured into mold between the gap to weld.
• The molten metal solidifies and weld is completed.

11. PREPARATION OF THERMITE
 The mixture of aluminum and iron oxide is placed in a
crucible.
 Barium Peroxide is added to the crucible. Barium peroxide
arises by the reversible reaction of O2 with barium oxide. The
peroxide forms around 500°C and oxygen is released above
820°C .
 Mixture is ignited using a match stick (or) small magnesium
wire. So combustion takes place in the crucible
 Due to combustion, thermite mixture becomes superheated
liquid within max. time of 30 seconds.

13. 3-D SIDE VIEW
OF THERMITE
WELDING !!!

14. That superheated liquid (pouring metal)
have temperature of 2500--3000°C
(around 5000°F)
 The reduction of ferric oxide by
aluminum is highly exothermic and
therefore the iron formed will be in the
molten state.
Aluminum is chosen as metal since it
has strong affinity towards oxygen and
its oxide, Al2O3 is a highly exothermic
compound.
Reaction takes place:
Fe2O3 + 2Al --------> Al2O3 + 2Fe +
heat
REACTION OF THERMITE

16. THIS IS HOW
RAILWAYS TRACKS
ARE JOINED
THANK YOU !!!!