fillermetal

Fillermetal, or filler metal, is a material added during metal joining to supplement the base metals and complete the joint. It melts and mixes with the base metal in welding, brazing, or soldering to form a metallurgical bond, fill gaps, and tailor the finished properties of the assembly. Filler metals are supplied in various forms, including wires and rods for welding, brazing alloys in rod or paste form, and solder pastes for low-temperature joins.

Filler metals span steel and stainless steel, aluminum, copper, nickel, and specialty alloys such as titanium. In welding, common steel fillers include ER70S-6 wires; aluminum fillers include 4043 or 5356; stainless steel fillers include 308L or 316L. Brazing fillers include copper-phosphorus, silver-copper eutectics, and nickel-based alloys; solders include tin-lead or tin-silver-copper alloys.

Selection depends on base metal compatibility, melting temperature, joint design, service conditions, and code requirements. The filler metal should have a compatible alloy system and appropriate flow characteristics to ensure sound deposition. Standards from organizations such as the American Welding Society and ISO classify and constrain filler metal compositions and uses.

In practice, the chemistry of the filler metal influences weld metallurgy, heat-affected zone behavior, and corrosion resistance. Proper storage, handling, and safety practices are important, and materials are often supplied with certificates of compliance.