©
COPYRIGHT 1998 THE ESAB GROUP, INC. LESSON
II is picked
up at the contact tube. The electrode moves into the loose flux and the
arc is initiated.
The flux is deposited from a separate container that moves at the same pace
as the electrode
assuring complete coverage (See Figure 20). 2.6.1
Submerged
Arc Flux
- The flux helps form the molten puddle, slows the cooling
rate, and acts as a protective shield.
The flux, which is in close contact with the arc, is fused
into a slag cover and that which is
not fused is collected for reuse. The flux can contain alloying
elements that, when molten, will pass
into the weld metal affecting the metallurgy. Some fluxes
are specifically prepared for their
alloy altering capabilities while others, known as neutral
fluxes, are chosen when a minimal alloy
change is desired. Although these latter fluxes are
called "neutral", they still have the
ability to slightly alter the weld chemistry. FIGURE
20 FLUX HOPPER
LOOSE GRANULAR FLUX
MOLTEN PUDDLE
FUSED SLAG COVER
SOLIDIFIED WELD
METAL BASE
METAL ELECTRODE
SUBMERGED ARC WELDING
2.6.2
The
Welding Gun
- Although there are hand-held welding guns for the submerged
arc process, the majority of SAW is
done with fully automatic equipment. The basic compo-
nents include a wire feeder, a power
source, a flux delivery system, and in some instances, an
automatic flux recovery system.
2.6.3
Power
Sources -
The power source can be a constant current AC transformer, or it
may be a DC rectifier or generator
of either the constant current or constant voltage variety.
The power source must be rated for
high current output. When current requirements exceed
the value of a single machine, two
or more of the same type may be connected in parallel. 2.6.4
Equipment
- Most submerged arc welding is done with DCEP because
it provides easy
arc starting, deep penetration and excellent bead shape. DCEN provides the
highest
