FLUX AND FILLER METALS

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FLUX    

The flux should be sufficiently active to decompose oxides without corrosion damage to the metal.

It should be economical to use and remove from the joint after welding.

It should be effective for the time and temperature range used for welding.

It should have a lower fluidity than the filler.

FILLER METALS

It should have a melting point lower than the base metal and be sufficiently

  fluid to flow and cover the metal & distribute into joints.

It should have sufficient homogeneity and strength in the composition to be

  viscous and not free flowing.

It should wet the surface of the metal and form a strong bond.

The contents – constituents – impurities- should not form an alloy with the

  parent metal such that the parent metal will be weakened or embrittle the joint.

It should readily react with the metallic oxides and dissolve them before the

  molten metal solidifies.

The slag so formed should be such that it will float and cover the welded metal from the atmosphere



Advantages of Welding in Shipbuilding

It allows for easy prefabrication.

Easier to make water tight and oil tight.

Easier to make joints.

Requires lesser skilled labour.

Very strong.

Advantages for the owner

Reduced hull weight – more dwt

Lesser maintenance – lesser slack rivets

Smoother hull – lesser resistance.