To avoid galvanic corrosion when welding stainless steel, how should filler metal be chosen?

To avoid galvanic corrosion when welding stainless steel, how should filler metal be chosen?

• A. Very high conductivity
• B. Completely different composition
• C. Lower melting point than base metal
• D. Similar corrosion resistance and compatible mechanical properties

Answer: (D)

Galvanic corrosion happens when two different metals are in electrical contact in a corrosive environment, creating a galvanic couple. When welding stainless steel, the safest choice for filler metal is one whose corrosion resistance and mechanical properties closely match the base metal. Keeping the filler's alloying content similar to the stainless being welded minimizes the electrochemical potential difference at the weld and heat-affected zone, so there’s less driving force for corrosion to occur at the joint. If the filler has a radically different composition or corrosion resistance, a galvanic cell can form between the weld and the surrounding metal, accelerating corrosion over time. The filler also needs to harmonize with the base metal’s strength and ductility; a mismatch can lead to stress, cracking, or poor weld performance. So choosing filler with comparable corrosion resistance and compatible mechanical properties keeps the weld area from becoming a preferential corrosion site.

Galvanic corrosion happens when two different metals are in electrical contact in a corrosive environment, creating a galvanic couple. When welding stainless steel, the safest choice for filler metal is one whose corrosion resistance and mechanical properties closely match the base metal. Keeping the filler's alloying content similar to the stainless being welded minimizes the electrochemical potential difference at the weld and heat-affected zone, so there’s less driving force for corrosion to occur at the joint. If the filler has a radically different composition or corrosion resistance, a galvanic cell can form between the weld and the surrounding metal, accelerating corrosion over time. The filler also needs to harmonize with the base metal’s strength and ductility; a mismatch can lead to stress, cracking, or poor weld performance. So choosing filler with comparable corrosion resistance and compatible mechanical properties keeps the weld area from becoming a preferential corrosion site.