In submerged arc welding, what role does the slag play?

The role of slag in submerged arc welding is primarily to support the weld pool while simultaneously providing a protective shield over it. During the welding process, a granular flux is utilized that melts and forms a slag layer on top of the weld bead. This slag serves several important functions.

By supporting the weld pool, the slag helps to control the shape and integrity of the weld as it solidifies, promoting uniform penetration and minimizing defects. Furthermore, the slag acts as a barrier against atmospheric contamination, protecting the weld from impurities that can compromise its quality.

While the cooling effect and oxidation prevention are considerations in welding, the specific and crucial role of the slag in submerged arc welding is centered around its ability to support the weld pool and shield it effectively, making it fundamental to achieving a high-quality weld.