What is the effect on the Submerged Arc Welding (SAW) weld when switching from Direct Current Electrode Positive (DCEP) to Direct Current Electrode Negative (DCEN)?

Switching from Direct Current Electrode Positive (DCEP) to Direct Current Electrode Negative (DCEN) during Submerged Arc Welding (SAW) influences the characteristics of the weld significantly. When using DCEN, the heat generated in the arc is transferred more efficiently to the base material than to the electrode. This results in an increased deposition rate because more heat contributes to melting the filler material and transferring it into the weld pool.

However, the change also affects the penetration of the weld. With DCEN, the arc tends to provide less penetration compared to DCEP because the heat is mostly concentrated at the surface of the base metal rather than being driven deeper into the material. Therefore, the combination of increased deposition and reduced penetration is characteristic of the welding process when using DCEN.

This understanding is crucial for welders and engineers in selecting the appropriate polarity for specific applications, balancing the trade-offs between penetration and deposition according to the requirements of the weld joint and the materials involved.