What technique is best for preventing slag inclusion during welding?

Using a clean filler material is essential for preventing slag inclusion during welding. Slag inclusion occurs when impurities and slag from the welding process become trapped in the weld bead, weakening the joint and potentially leading to failure. A clean filler material is crucial because contaminants such as oil, rust, or dust can introduce additional impurities into the weld, increasing the risk of slag inclusion.

When the filler material is clean, it allows for a smoother welding process, ensuring that the arc can transfer heat effectively and that the weld pool remains stable. This stability helps in the proper formation of the weld bead without trapping unwanted materials, which is vital for maintaining the integrity of the joint and ensuring the desired mechanical properties of the weld.

In this context, while techniques such as limiting heat input and adjusting travel speed can impact the quality of the weld, they do not directly address the core issue of cleanliness regarding the filler material. Thus, maintaining a clean filler is the most direct method for minimizing the risk of slag inclusion.