ELECTROSLAG

WELDING

http://en.wikipedia.org/wiki/File:Electroslag.png

•Electroslag Welding is a welding process, in which the heat is generated by an electric current passing between the consumable electrode (filler metal) and the work piece through a molten slag covering the weld surface.

•(ESW) is similar to electrogas welding, but the main difference is the arc starts in a different location.

What is electroslag welding ?

process

• Prior to welding the gap between the two work pieces is filled with a welding flux.

• Electroslag Welding is initiated by an arc between the electrode and the work piece (or starting plate).

• Heat, generated by the arc, melts the fluxing powder and forms molten slag.

• The slag reaches a temperature of about 3500°F (1930°C).

• This temperature is sufficient for melting the consumable electrode and work piece edges.

• Metal droplets fall to the weld pool and join the work pieces.

• The slag, having low electric conductivity, is maintained in liquid state due to heat produced by the electric current.

• Electroslag welding is used mainly to join low carbon steel plates and/or sections that are very thick.

• It can also be used on structural steel if certain precautions are observed.

Uses

• This process uses a direct current (DC) voltage usually ranging from about 600A and 40-50V, higher currents are needed for thicker materials.

• Because the arc is extinguished, this is not an arc process.

Advantages

•High deposition rate - up to 45 lbs/h (20 kg/h).

•Low slag consumption (about 5% of the deposited metal weight).

•Low distortion.

•Unlimited thickness of work piece.

Disadvantages

•Coarse grain structure of the weld.

•Low toughness of the weld.

•Only vertical position is possible.