Usually it is welded with direct current with the positive pole at the wire electrode. Other polarities are also possible.
The power supplies are usually rectifiers. It has to be considered that, due to the high stage of mechanism, there are high intensities of current placed at disposal at a duty cycle of 100 %.
A downward power supply characteristic (external regulation) is used at wire electrodes exceeding 3 mm, if the wire electrode diameter is small, a constant current characteristic is used.
Welding Seam Preparation: Due to the deep penetration a special seam preparation and the use of backing is necessary.
Backing is standardised according to DIN EN ISO 9692-2.
The Voltage Influences Seam Width
The Amperage Mainly Influences the Penetration
As reference value 100 A can be chosen in order to create a penetration of approx. 1 mm in the square butt joint.
Usual amperage at a wire electrode’s diameter of 4 mm is at I = 600 A.
From these values a current load results which is usually at about 150 A/mm wire diameter. Then the current density is at about 48 A/mm2.
It has to be considered that the current density, not the amperage, strongly influences the extend of the penetration.
The Welding Speed Influences the Weld Width as well as the Weld Depth
The usual welding speed is at about 55 cm/min. If too low welding speeds have been chosen the arc burns on the forward travelling welding pool which has a flat penetration and also lacks of fusion.
From the single parameter results a welding parameter replacement of
I = 600 A
U = 30 V
v = 55 cm/min
Wire diameter = 4 mm
which is to be seen as basic parameter. From these values results a for the submerged arc welding typical energy per unit length of approx. 20 kJ/cm.