(b) Possibility -2 : W is more noble than A or B - In this case W will be cathodic and both A a B will be anodic. So A & B will be corroded and W will be corrosion free. This may be a situation if we want to join Cu to steel with M67F. Since M67 contains high amount of silver ( highly noble metal ) , M67F weld (W) will be more cathodic than Cu (A) and steel (B). This is one of the reason to declare M67F weld as good corrosion resistant weld in our Magna encyclopedia under M67F.