18 Controllable
Variables During Welding A knowledge
and control of the variables in submerged arc welding are essential if welds of
good quality are to be consistently obtained.
The variables, in the approximate order of their importance, are:
1. Welding current 2.
Welding voltage 3. Welding speed
4. Width and depth of the layer of submerged are welding
flux 5. Mechanical adjustments
These variables are discussed in the following paragraphs.
a. Welding Current
Welding current is the most influential variable. It
controls the rate at which welding wire is burned off, the depth
of fusion, and the amount of base metal fused. If the current is too high, the
depth of fusion will be too great and the
weld may melt through the backing. In addition to this, the higher heat developed
may excessively extend the heat affected
zone of the adjacent plate. Too high a current also means a waste of
power and a waste of welding wire in the form of excessive
reinforcement. If the current is too low, there is insufficient
penetration and not enough reinforcement. b.
Welding Voltage Next in importance
to welding current is the welding voltage. This is the potential difference between
the tip of the welding wire and the surface
of the molten weld metal. The welding voltage varies with the length of
the gap between the welding wire and the molten weld
metal. If the gap increases, the welding voltage increases;
if the gap decreases, the welding voltage decreases. Continued
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