Gas Tungsten Arc Welding (GTAW) WELD 250 Practice Test

When two different metals are welded together, they can form a galvanic couple in the presence of an electrolyte. Because each metal has a different electrochemical potential, one metal becomes anodic and corrodes faster while the other is protected. This galvanic corrosion tends to occur at the weld and heat-affected zones, where the metals meet and the microstructure is altered by heat. In service, especially in moist or salty environments, this can significantly shorten the joint’s life. To reduce risk, engineers choose metals with closer galvanic potentials, use a compatible filler metal, or apply barriers to prevent electrolyte contact and crevice buildup. Magnetic interference and color matching aren’t welding concerns, and while mismatched thermal conductivity affects heat input and distortion, it’s not the primary corrosion issue in dissimilar-metal GTAW joints.