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Weldability

  Fusion welding     1 of 3
 
Fusion welding involves a heat source and may involve the use of a filler material such as a consumable electrode or a wire fed into the weld pool. These processes also use a protective layer between the atmosphere and the molten metal, either in the form of gas shielding or a flux which melts to give a viscous slag on the weld metal that eventually solidifies and can be removed. There are several different types of fusion welding processes that can be used. The table below gives some typical applications for the different procedures and the typical characteristics of technique.

 

 

Cost

Cleanness of the weld

HAZ width

Level of automation

Thickness of plate

Comments and typical applications

Manual Metal Arc (MMA)

Low

Poor - OK

5 - 6 mm

Not

Any - multipass

Only use for relatively short runs, for example car repair welds, small repair welds on bridges, oil rigs etc.

Submerged arc welding (SAW)

Medium

Poor

7 - 10 mm

Very high

Any - multipass

Only use horizontally, used for high production runs for example pipelines.

Metal inert gas (MIG)

Low - Med

OK

3 - 4 mm

Medium

Any - multipass

Used for production runs on thinner sections than SAW

Tungsten inert gas (TIG)

Low - Med

Good

2 - 3 mm

 

Medium

Any - multipass

Used for similar applications as MIG but for longer production runs

Laser

Very high

Very good

< 0.5 mm for 12 mm thick plate

Very high

up to 30 mm

Used for reasonably higher specification welds, becoming more widespread as cost comes down, for example automotive bodies. Low distortion process, requires good fit up no filler wires (reduces cost).

Electron Beam

Very high

Very good

< 0.5 mm for 12 mm thick plate

Low

up to 250 mm

Requires a vacuum, very expensive, used in aerospace industry predominantly can be used for welding Al, Ti, Cu, stainless steels and reactive metals. Low distortion process, requires good fit up no filler wires (reduces cost).

 

 

 
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