The final step in MIG welding aluminum is to choose the correct filler alloy

Author: Kunli / 2023-06-22

Aluminum Alloy Welding Wire

Aluminum Alloy Welding Wire is a special welding wire that contains an aluminum alloy in addition to the regular arc welding electrode material. The alloy increases the strength and ductility of the welded joint. These specialty wires are available in a wide range of diameters and lengths, suitable for most welding applications. They can be used in both MIG and TIG welding. It is important to understand the characteristics of the specific alloy when selecting a welding process and wire type for a given application.

Welding aluminum is different than welding mild steel, and requires special care to achieve good results. Aluminum has a low melting temperature and high thermal conductivity. This creates a challenge when welding, since it is easy to burn through the aluminum base metal with too little heat input. In addition, aluminum has a strong affinity for oxygen and produces an oxide layer on the surface that must be removed prior to welding. This oxide layer has a higher melting point than pure aluminum, which can cause lack of fusion defects in the welded joint.

The first step in MIG welding aluminum is removing the oxide layer with a stainless steel brush or chemical solution. This is important because the oxide inclusions cause lack of fusion in the welded joint and reduce its strength. Embedded impurities can also burn during the welding process, producing gases that form porosity in the weld.

Once the oxide layer is removed, you can MIG weld using a push (forehand) travel direction. This is important because the aluminum will heat up rapidly as you weld, and you want to keep your travel speed high enough to avoid burn-through. It takes practice to determine the best travel speeds for aluminum welding, especially when working with thinner pieces.

When MIG welding aluminum, it is necessary to use a 100% argon or an argon-helium mixture as the shielding gas. Helium can be added to argon to increase the welding speed and depth of penetration, which is especially useful when welding thick aluminum sections. It is important not to mix helium with carbon dioxide, as this can react with the aluminum and reduce its tensile strength.

It is also a good idea to use a graphene liner set up or a spool gun when MIG welding aluminum. This is because the soft aluminum wire can kink in a standard MIG gun meant for mild steel, and this can cause inconsistent arc performance.

The final step in MIG welding aluminum is to choose the correct filler alloy. There are a variety of filler alloys, from pure aluminum to varieties with added copper, silicon or magnesium. Choosing the right alloy for your application is key to minimizing cracking sensitivity in the solidifying weld, which can result in distortion and loss of tensile strength. In general, it is better to use a 4043 or 5356 alloy for aluminum welding. These two filler alloys offer good ductility and shear strength, and match the chemistry of most aluminum alloys.