Aluminum alloy 4943 filler metal is the first aluminum filler alloy to be developed for wrought commercial applications since the 1960’s and has recently received AWS A5.10 approval. It is designed to provide a high strength alternative to 4043 while maintaining the ease of welding and other advantages of 4043. Alloy 4043 filler metal is a popular aluminum/silicon filler alloy for general purpose welding applications but can show significant variability in strength based on welding conditions and the level of base metal dilution. Alloy 4943 filler metal is formulated to be welded with the same weld procedure specifications as 4043, address 4043 shortcomings while maintaining the same excellent corrosion characteristics, low melting temperature, low shrinkage rate, higher fluidity, and low hot cracking sensitivity in most applications. Alloy 4943 welds exhibit low welding smut and low discoloration similar to 4043. In addition to the higher as welded strength, the new 4943 filler alloy is heat treatable and has demonstrated its improved strength characteristics in the post weld solution heat treated and artificially aged condition when compared to the currently used heat treatable filler alloy 4643, which has been generally employed for welding the 6xxx series base materials that are post weld heat treated.
This article explains the test results of this alloy development project, shows the alloy properties compared to the traditional filler metal alloys and offers potential applications and benefits. The fundamentals of aluminum-silicon alloys are also presented. Also included are 4043 baseline test results highlighting 4043 property variability susceptibility from the weld procedure.