CEMP-E
TI 809-26
1 March 2000
Flux contamination through contact with oil, moisture, dirt, scale of other contaminants may occur,
therefore care is needed. Some loss of fine particulate matter may also occur with flux recovery,
b. Filler Metal Designation, Specification and Certification. Submerged Arc Welding (SAW) filler
materials, the electrodes and fluxes, are classified under AWS A5.17 for carbon steel electrodes and
fluxes, and AWS A5.23 for low alloy steel electrodes and fluxes. Because SAW is dependent upon both
components, flux and electrode, the classification system integrates both materials. After an electrode
and flux combination is selected and a test plate welded, the flux-electrode classification may be
established. Specimens are extracted from the weld deposit to obtain the mechanical properties of the
flux-electrode combination, which must meet specific compositional and mechanical property
requirements.
(1) The classification systems for SAW are summarized in Tables C-14 and C-15 for AWS A5.17
materials, and Table C-16 for AWS A5.23 materials. Low alloy steel SAW electrodes and fluxes
classified under AWS A5.23 have a more complex classification system, because of the variety of alloys
that may be involved, and because the composition of both the electrode and the resultant weld metal
must be specified.
(2) Because the submerged arc welding process is frequently used for pressure vessel fabrication
where assemblies are stress relieved, many submerged arc materials have been classified for the post
weld heat treated, or stress relieved, condition. When this is done, a "P" is placed in the designation
rather than an "A". For structural work, which is seldom stress relieved, the "A" classification is commonly
used. Flux-electrode combinations classified in the post weld stress relieved condition may not exhibit
notch toughness when used in the as-welded condition, therefore investigation into weld metal properties
is warranted whenever the weld will be used differently than the filler metal classification condition.
(3) Fluxes are manufactured using one of four basic processes, and are further classified as
neutral, active or alloy fluxes, based upon their performance characteristics during welding.
(4) Fused fluxes are made by blending deoxidizing and alloying ingredients, as necessary, and
then heating the mixture in a furnace until completely melted. A glass-like fused product is formed as the
liquid is cooled to ambient temperature, and later ground to the sizes required for welding. Fused fluxes
are nonhygroscopic, meaning they will not absorb water, but may be contaminated by moisture or other
products that adhere to the outside of particles. Fused fluxes are not subject to chemical segregation
during reuse because the complete composition is in each particle and cannot be separated. Fused
fluxes may have less than desired amounts of deoxidizer and ferro-alloy ingredients because of losses
that occur from the high temperatures during the manufacturing process. Fused flux performance can be
impeded by loss of fines during recycling. Fused fluxes with the required chemical composition generally
give the best low hydrogen welding performance.
(5) Bonded fluxes are made by combining all required chemical ingredients with a binder and
baking the product at low temperature to form hard granules, then broken up and screened for size.
Bonded fluxes contain chemically bonded moisture and can absorb moisture as well. Because the
product is baked at low temperature, deoxidizer content or alloying elements that can be added as ferro-
alloys or as elemental metals are not a problem as with fused fluxes. Bonded fluxes may segregate
during use and reuse, and gases may be produced in the molten slag during welding. Bonded fluxes tend
to break down during recycling and increase the percentage of fines.
(6) Agglomerated fluxes are similar to bonded fluxes in their method of manufacture, except that
the binder is a ceramic material that requires baking at higher temperatures. This may limit deoxidizer or
C-23
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