Submerged Arc Welding Technical Handbook - Esab

The submerged arc welding
process
Submerged arc welding (SAW) is a
method in which the heat required to
fuse the metal is generated by an arc
formed by an electric current passing
between the electrode and the workpiece.
A layer of granulated mineral
material known as submerged arc
welding flux covers the tip of the
welding wire, the arc, and the workpiece.
There is no visible arc and no
sparks, spatter or fume. The electrode
may be a solid or cored wire or a strip.
SAW is normally a mechanised process.
The welding current, arc voltage, and
travel speed all affect the bead shape,
depth of penetration and chemical
composition of the deposited weld
metal. Since the operator cannot
observe the weld pool, great reliance is
placed on parameter setting and
positioning of the electrode.
General scope:
range between 100 and 3600 amps
The welding operation
When the apparatus is set into
operation, several things occur in quick
sequence:
through the hopper tube and
continuously distributes itself over the
seam a short distance ahead of the
welding zone.
feed the welding wire into the joint at
a controlled rate
current flows between the electrode
and the work.
automatically) to travel along the
seam.
The tremendous heat evolved by the
passage of the electric current through
the welding zone melts the end of the
wire and the adjacent edges of the
work-pieces, creating a pool of molten
metal. The submerged arc welding flux
completely shields the welding zone
from contact with the atmosphere.
As the welding zone moves along the
joint, the fused submerged arc welding
flux cools and hardens into a brittle,
glass-like material which protects the
weld until cool, then usually detaches
itself completely from the weld.
Benefits
deep and safe penetration
Limitations
during welding possible
Equipment – Basic Principles
The high welding speeds and
deposition rates which are
characteristic of submerged arc welding
require automatic control of the motor
that feeds the welding wire into the
weld. No manual welder could smoothly
deposit welding wire at speeds
comparable to those of a submerged
arc welding machine. Nor could he
maintain the same precise control of
welding parameters. The automatic
control and power supply system used
in submerged arc welding operates to
maintain a constant voltage and
current.
Relationship of welding voltage to
distance between welding wire and
work-piece
The welding voltage is proportional to
the length of the current path between
the welding wire and work-piece:
work-piece increases, the welding
voltage will increase.
work-piece decreases, the welding
voltage will decrease.
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