In welding, what is a filler metal?

The concept of filler metal is essential in welding as it plays a critical role in the process. Filler metal is primarily used to fill the joint between the workpieces being welded. During welding, the base metals are heated to a molten state, and the filler metal is added to the joint to facilitate that connection. This addition enhances the structural integrity of the final weld, ensuring that the joint can withstand the necessary mechanical forces and provide durability.

In the context of welding procedures, it is crucial to select the appropriate filler metal based on the materials being joined and the specific requirements of the intended application. The filler metal must have compatible properties with the base materials, including melting temperature and chemical composition, to ensure a successful bond.

The other choices describe different aspects of welding processes but do not accurately define filler metal. For instance, while one choice mentions a protective material applied before welding, it refers to shielding gases or coatings that prevent contamination but do not contribute to the joint strength directly. Another option incorrectly suggests that filler metal forms the base material, while the base material remains the workpieces being joined. Thus, the key characteristic of filler metal is its function in bridging gaps and reinforcing joints during the welding process.