5. • Coalescence is produced by heating with an arc between a bare
wire electrode and the work.
• Welding zone is shielded by a blanket of fusible granular flux
material supplied directly on the weld seam.
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6. • Pressure is not used. Electrode act as a filler metal.
• Electrode is copper-plated in outside surface(for electrical
conductance)
• larger diameter electrodes are used. So in a single pass of
welding a 25mm weld can be made.
• The flux acts as a thermal insulator by promoting deep
penetration of heat into the workpiece.
• Suitable to weld straight welds in a flat position.
• Also suitable for circular shapes if the work piece is rotated
under the welding head.
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7. Used to weld: low carbon steels, high strength low alloy
steels, chromium steels.
Applications:
• To weld large diameter pipes, boiler pressure vessels,
railroad tank cars, structural members in ships and
cylinders.
Advantages:
Joints can be prepared with a shallow V-groove, resulting in
lesser electrode consumption.
Wire electrode is inexpensive
Weld spatters are eliminated
Nearly 100% deposition is achieved.YoucaN
8. Disadvantages:
• It can not be used for plates less than 5mm thick.
• Flux is subjected to contamination that may cause weld
porosity.
• Chlorine, Aluminium, Magnesium, Lead, Zinc can not be
welded.
• Slag has to be removed continuously after it has melted in
order to avoid entrapment between passes.
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18. • 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.
• Prior to welding the gap between the two work pieces is filled
with a welding flux.
• The slag, having low electric conductivity, is maintained in liquid
state due to heat produced by the electric current.
• Current is about 600A at 40 to 50V.(depends on “t”)
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Flux consisting of lime, silica,
manganese oxide, calcium fluoride and
other compounds
19. • The slag reaches a temperature of about (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.
• In the outer a water cooling circuit helps for quick solidification.
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20. • Used to join 50mm to more than 400mm thick
plates.
• Travel speed is 12 to 36mm/min.
• Application:
Used in large structural steel sections, such as heavy
machinery, bridges, oil rings, ships
and nuclear reactor vessels.
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