TI 809-26
ferro-alloy content due to high temperature losses. Agglomerated fluxes are generally considered
(7) Mechanically mixed fluxes can be a mixture of any flux type in any desired proportion, are
subject to segregation, and will have the attributes of their components.
description and limitations of theses fluxes is provided in the Annexes to the AWS A5.17 and A5.23 filler
metal specifications.
manganese and silicon content, is relatively unaffected by changes in welding procedure variables,
primarily the voltage that determines arc length. For both active and alloy fluxes, the weld metal
(10) Active fluxes have small additions of manganese and silicon, or both, to help offset the effects
of welding though mill scale and light coatings of rust. With active fluxes, a change in arc voltage will
are more resistant to porosity and cracking than welds made with neutral fluxes, active fluxes are often
used in making single pass fillet welds. Active fluxes intended for single pass fillet welding should not be
combine with the same elements in the electrode to produce weld metal with unacceptable properties.
The chemistry may build to unacceptable levels in larger multipass welds, therefore welding with active
with low levels of manganese and silicon. Where all mill scale and other contaminants are removed prior
to welding, the surface contamination tolerance of active fluxes is not needed. Continued recycling of
(11) Alloy fluxes contain alloys intended to improve the strength or corrosion resistance of the weld
metal, or both, and the composition of the weld metal is highly dependent upon the alloy content of the
mechanical properties of the weld. Alloy fluxes, properly used with carbon steel electrodes, provide a
low-cost method of producing corrosion resistant weld metal for joining weathering steels. Unlike active
in the alloy content.
c. Advantages, Disadvantages and Limitations. Very high currents can be used in submerged arc
and deep penetration. The slag above the molten weld puddle acts as an insulating blanket,
concentrating heat in the welding zone and preventing rapid escape of heat. Deep penetration allows the
High travel speeds reduce the total heat input into the joint, reducing distortion.
(1) SAW welds generally have good ductility and toughness, and a uniform bead appearance
reducing cleaning and surface preparation costs. The covered arc allows SAW to be operated without the
need for extensive shielding to protect the operators from the high intensity arc created by the high
protection.
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