While the standard encompasses a wide variety of alloys, two of the most popular and versatile types of **aluminum filler metal** are **ER4043** and **ER5356**.
**ER4043** is a highly popular **aluminum-silicon alloy**, typically containing about 5% silicon.
It is prized for its excellent fluidity and superior crack resistance, making it the ideal choice for welding heat-treatable alloys like the 6xxx series and various aluminum castings.
This wire is a go-to option for applications such as automotive parts, bicycle frames, and general fabrication where a clean, bright weld finish and a low melting point are advantageous.
**ER5356** is an **aluminum-magnesium alloy**, with approximately 5% magnesium.
This alloy is valued for its high tensile strength, excellent ductility, and outstanding corrosion resistance, especially in marine environments.
It is the preferred filler metal for welding 5xxx series alloys and other high-strength aluminum base metals in structural applications, including shipbuilding, trailer manufacturing, and rail car construction, where durability and robust performance are paramount.