Why is it important to match the filler wire to the base material?

Matching the filler wire to the base material is fundamentally important to ensure compatibility and strength of the welded joint. When the filler wire is made of the same or similar material as the base metals being joined, it allows for a proper metallurgical bond. This compatibility helps prevent issues such as cracking, peeling, or other types of failures that can occur at the weld interface.

Additionally, using the correct filler material contributes to the overall mechanical properties of the weld, such as tensile strength and resistance to corrosion. The filler wire should ideally have similar expansion and contraction characteristics to that of the base materials as well, which helps maintain the integrity of the weld through various temperature cycles.

While appearance and cost are considerations in the welding process, they do not directly impact the strength and integrity of the weld joint as the compatibility of materials does. Ensuring a strong and reliable weld is crucial for the performance and longevity of the final product.