What About Aluminum Filler Rod?
toyota1515 > 07-11-2022, 09:12 AM
From its strength and versatility to its corrosion resistance, aluminum offers benefits that make it an appealing material for a variety of industries. The material, however, is not without its challenges when it comes to welding. Because of its low melting temperature and high thermal conductivity, extra care must be taken to prevent burn through on thinner material and to ensure adequate fusion or penetration on thicker material. Using the appropriate equipment— machines that offer Pulsed MIG capabilities or TIG capabilities — is important. So too is selecting the right filler metal and understanding the weld characteristics each type provides.
Aluminum Welding
From its strength and versatility to its corrosion
resistance, aluminum offers benefits that make
it an appealing material for a variety of industries.
There are many aluminum filler metals available in the marketplace, including those for applications found in aerospace or architectural structures to filler metals for heat exchangers, trailer fabrication and more. The filler metals range from pure aluminum to varieties with added copper, silicon or magnesium.
Among the variety of aluminum filler metals, 4043 and 5356 alloys are the most common and the least expensive. Together, those filler metals are used for welding about 80 percent of the time and are available in wires for MIG welding or cut-lengths (often called filler rods or straight lengths) for TIG welding. Knowing how to choose between the two alloys, as well as the characteristics each provide is important to producing good weld quality.
Aluminum filler metal characteristics
As with any type of filler metal, 4043 and 5356 aluminum alloys each have unique characteristics.
4043 filler metals tend to have a more fluid weld pool due to the addition of silicon (5 percent), which allows the bead to ‘wet out’ or flow into the base metal more easily. This characteristic produces a more aesthetically pleasing weld requiring less clean up, reduces leaks and minimizes cracking.
5356 filler metals contain 5 percent magnesium. As with the silicon in a 4043 product, the addition of this alloying element affects the performance of the filler metal. In this case, the magnesium increases the strength and toughness of the weld. When welding with 5356 aluminum filler metals, the resulting weld tends to be rippled rather than smooth and due to the 5 percent magnesium, more smut (black soot) could be present at the edges of the weld that the welding operator will need to clean.
Both 4043 and 5356 filler metals operate with 100 percent argon shielding gas, as it provides good arc initiation and stability. Thicker aluminum applications sometimes require the addition of helium, which improves heat transfer to the base metal and helps increase weld penetration. Helium can be expensive, though, and the application often sacrifices arc stability when it is added