Electro slag welding is an arc welding process where coalescence is produced by a molten slag that melts the filler metal and workpiece surface. During the process, a granular flux is placed in the joint gap and melts when current is applied, forming a 25.4-38.1 mm thick slag blanket. The slag's high resistance causes most of the heating, welding progressively from bottom to top. Advantages include simple joint preparation, ability to weld very thick plates in a single pass economically with low distortion and stress, while disadvantages are limitation to vertical welding and increased grain size and cracking risk.

2. INTRODUCTION
Electro slag welding is a type of arc welding wherein the
coalescence is produced by molten slag which melts the filler
metal metal and the surface of the work to be welded, electro
slag welding is quite similar to vertical submerged arc welding.

3. WOKING PRINCIPLE
1. In electro slag welding process a granular flux is placed in the gap
between the plate being welded and as the current is turned on, welding
takes place in a water-cooled copper shoes that bridge the gap of the joint
as the flux melts, a slag blanket from 25.4 to 38.1 mm thickness is
formed , high resistance of the slag causes most of the heating for the
remainder of the weld thus electro slag welding is a progressive process of
melting and solidification from the bottom to upward.
2. The maximum thickness that can be weld by this process is up to 100 mm
3. Molten metal and slag are retained in the joint by means of copper shoes
that automatically move upward as the weld progresses by means of a
temperature sensitive mechanism.

4. ADVANTAGES
1. Joint preparation is quite simple as compared to other
welding processes.
2. Very high thickness plate can be very easily welded in a single
pass more economically .
3. It gives extremely high deposition rate.
4. Distortion and thermal stresses are in very low percentage.
5. Flux consumption is very low.

5. DISADVANTAGES
1. Process is only limited to vertical position.
2. Electro slag welding tend to produce rather large grain size.
3. Complex shape joint cannot be welded by this process.
4. More chances of hot cracking and notch sensitivity in the heat
affected zone.