Filler metal is defined as which of the following in welding terminology?

• A. Filler
• B. Base
• C. Alloy
• D. Core

Answer: (A)

Filler metal describes the material added to the weld joint to fill the gap and become part of the weld metal. In welding, the base metal are the pieces being joined, and they may be melted or partially melted during the process. The filler metal is melted and fuses with the base metal to form the weld bead and achieve the desired cross-section and properties of the joint. It can come as a wire, rod, or powder and is chosen to supplement the base metal’s characteristics, such as strength and corrosion resistance. The term directly reflects its role—filling the joint—while the other terms refer to the pieces being joined or to a broader category, not the function of the material in the weld.