gas (if required). The amperage should be sufficient to
maintain a steady arc and good pool control. The elec-
trode should be almost perpendicular to the weld, with
only a slight amount of drag angle. This will reduce pene-
tration; however, slag may flow forward and become
entrapped if the arc is too long. High-arc voltages and
long stickouts are fine for reducing penetration and mini-
mizing dilution, but they tend to cause lack of fusion and
slag entrapment.
The amount of dilution into the base material has a
direct effect on chemical content of the final pass. To
establish the amount of dilution of the weld metal, a test
can be made to determine the actual welding parameters
and the final results of the weld. Many surfacing elec-
trodes limit the final weld to a single layer to maintain the
desired surfacing qualities. During the test period, all
welding parameters must be recorded so the procedure can
be duplicated for the actual weld. If the desired qualities
are not achieved during the test period, another test must
be made with another set of welding parameters.
Surfacing welds are best applied in the flat position
to limit heat input and impart the best bead shape to the
completed weld. After the first pass is made, the
remaining passes are usually located on half of the
completed weld and half of the parent metal. The
distance moved over to make this next weld is called the
stepover distance. It must be maintained until all the
required welds are completed. Figure 12-4 shows a badly
worn track roller to be rebuilt by welding. Figure 12-5
shows the completed weld on the worn track roller. Note
how the welds are moved over on each circular pass.
Oscillated welds are made by moving the gun across
the weld path in a set pattern. These types of welds are
made more slowly. More distortion occurs, and base
material heat can affect the amount of dilution. Oscillated
welding is easily controlled on an automatic machine
where the oscillation parameters can be determined and
controlled. Welders using semiautomatic equipment
should make test welds with the proposed procedure and
production equipment to verify the actual welding
parameters to be used.
Each weld of the overlay should be made to a
specific procedure to maintain the chemical limits of the
final weld. A weld that does not meet this requirement
will fail in service, resulting in excessive repair costs or
jeopardizing the safety of the equipment operator.
104 Flux Cored Arc Welding Handbook
Figure 12-4. This tractor roller has been worn to the maximum
allowance. All welding surfaces have been cleaned, and the
unit is ready for welding.
Figure 12-5. A dual welding head is welding this roller. To
reduce smoke from the operation, a neutral flux is used with a
FCAW filler electrode. With automatic stepover programmed
into the operation, welding can continue until the layer is
complete.