4043 filler metal is a popular aluminum/silicon filler alloy for general purpose welding applications. Features/Benefits: Moderate strength (28 ksi typical). Low melting temperature/high fluidity. Low welding smut and discoloration. Low ductility, formability, and lower toughness. Moderate electrical conductivity and thermal conductivity. Excellent corrosion resistance. Low shrinkage rate/reduced distortion. Low hot cracking sensitivity in most applications.