What You Should Know about Welding Aluminum .
toyota1515 > 04-20-2023, 08:43 AM
A good understanding of aluminum's metallurgy, combined with the use of the latest technology, can help conquer weldability problems .
Alloying Elements .
Let's take a look at the different alloying elements.
Pure aluminum (1XXX series) the 1XXX series is easily welded with 1100 and 4043 alloys.
Copper, which carries a wrought alloy designation of 2XXX series, provides high strength to aluminum. This series is heat treatable and mainly used in aircraft engine parts, rivets and screw products. Most 2XXX series alloys are considered poor for arc welding because of their sensitivity to hot cracking. These alloys are generally welded with 4043 or 4145 series filler metals, which have low melting point to reduce the probability of hot cracking. Exceptions to this are Alloys 2014, 2219 and 2519 , which are easily welded with a 2319 filler metal.
Manganese (3XXX series) added to aluminum yields a nonheat-treatable series used for general-purpose fabrication and buildup. Moderate in strength, the 3XXX series is used for forming applications including utility and van trailer sheet. It is improved through strain hardening to provide good ductility and improved corrosion properties. Typically welded with 4043 or 5356 electrodes, the 3XXX series is excellent for welding and is not prone to hot cracking. Its moderate strength does prevent this series from being used in structural applications.
Silicon (4XXX series) reduce the melting point of aluminum and improves fluidity. Its principle use is as filler metal. The 4XXX series has good weldability and is considered a nonheat-treatable alloy . Alloy 4047 is becoming the alloy of choice in the automotive industry, as it is very fluid and good for brazing and welding.
Magnesium (5XXX series) , when added to aluminum, has excellent weldability with a minimal loss of strength and is basically not prone to hot cracking. In fact, the 5XXX series has the highest strength of the nonheat-treatable aluminum alloys. It is used for chemical storage tanks and pressure vessels at elevated temperatures, as well as for structural applications, railway cars, dump trucks and bridges because of its corrosion resistance. It loses ductility when welded with 4XXX series fillers due to formation of Mg², Si.
Silicon and Magnesium (6XXX series) combine to serve as alloying elements for this medium-strength , heat-treatable series. It is principally used in automotive, pipe, railing, structural and extruding applications. The 6XXX series is somewhat prone to hot cracking, but the correct choice of joint design and filler metal can overcome this problem. This series can be welded with either 5XXX or 4XXX series without cracking --- adequate dilution of the base alloys with selected filler alloy is essential. A 4043 electrode is the most common for use with this series --- Fig. 3.