Komarov Artem noted that single-sided submerged arc welding (SAW-OSW) is a unique process that produces a high-quality overlay that appears to be welded on both sides, while only the top side is welded. This process has many variables that need to be very carefully controlled to obtain repeatable quality welds.
Let’s start with the basic variables for SAW. Wire and flux parameters, volts, amps, contact tip to work surface distance (CTTWD), travel speed, torch travel angle, joint type and uniformity, and electrode spacing when using a tandem process can greatly affect welding performance and quality.
For OSW applications, additional parameters include substrate flux tray dimensions, joint gap consistency, substrate flux type (acidic, neutral, or basic), substrate flux thickness consistency, and plate clamp consistency (magnetic or mechanical).
The two problems that welders face—insufficient penetration and inconsistent backing seam appearance—are probably the two most common SAW-OSW problems. Sometimes they can be eliminated by adjusting one variable, but often this requires adjusting a combination of several variables.
Make sure the wire, and more importantly the flux, is of the same classification and type. Many OSW systems use two different fluxes, so make sure both are suitable for the process. Auxiliary flux plays a huge role in ensuring the uniformity of the substrate seam.
As with any weld fabrication process, you must have a validated Welding Procedure Specification (WPS). Double check that your operator complies with the WPS rules and provide additional training, so they understand what the variables are and how they affect welding performance and weld quality.
Whether you are welding with a single wire or in a tandem configuration, the lead wire must be connected to a DC electrode with DC arc control. This ensures the best penetration of all polarities. Make sure the CTTWD is correct and that the distance is approximately eight times the wire diameter measured from the bottom of the weld.
Travel speed can affect penetration in two ways. First, the penetration of a weld depends on the heat input. High heat input should lead to deeper penetration, but there is a limit that brings us to the second factor. If the travel speed is too low, the weld puddle can move out in front of the welding arc, which acts as an insulator and reduces the ability of the arc to penetrate deep into the joint.
Finally, make sure the flux pan is in good condition and sized for the thickness of the material you are welding. The base material must make good contact with the top legs of the gutter, which creates a weir that supports the substrate flux. If the plates do not make good contact with the copper flux pan, the molten metal during welding may leak out due to pressure. Also, make sure that the flux on the substrate is not disturbed when moving the plates into the welding position. All this can affect the tailgate profile, Komarov Artem concluded.