What is the first bead made when welding two pieces of metal together called?

The first bead made when welding two pieces of metal together is referred to as the root pass. This initial weld is crucial, as it establishes the foundation for the entire weld joint. The root pass penetrates into the joint and is responsible for fusing the two base materials together. It is typically applied in a groove joint and ensures that the base metals are adequately fused before any additional layers or passes are added on top.

Understanding the significance of the root pass is essential for achieving a strong and reliable weld. If the root pass is not executed properly, it can lead to defects in the subsequent layers, thus compromising the integrity of the weld. This emphasizes the importance of technique and control during the welding process at this stage.