They are extremely sensitive to hot cracking and are the least weldable aluminum alloys. Specifically, 2024 is the least weldable. But there are a couple exceptions, 2219 and 2519, which can be readily welded with 2319 or 4043 filler metal.
So why is aluminum so difficult to weld? This material is soft, highly sensitive and is insulated by a tough oxidized layer. While in its molten state, aluminum is susceptible to impurities, which can lead to porous, weak welds.
What Makes Welding 2024 and 7075 Challenging? Aluminum alloys of 2024 and 7075 can become susceptible to stress corrosion cracking after welding. This phenomenon is particularly dangerous because it is not detectable immediately after welding. The cracking usually develops later when the component is in service.
First, some aluminum alloys cannot be welded without filler materials. Alloys such as 6061 will undergo solidification cracking if welded without filler metal. Furthermore, the correct filler material must be selected. For instance, welding a 6061 alloy with a 6061 filler metal will result in weld failure.
Welding of qualifying 7000-series alloys can be done using 5356 or 2319 alloy welding wire, both of which can produce porosity-free welds of acceptable strength that can match the aluminum alloy's integrity.
Generally speaking, aluminum's capacity to be welded (weldability) varies between different alloy series. It can range from “very good” to “unweldable by common arc welding methods.” That said, most aluminum alloys can be welded under the right conditions and by taking proper precautions.
5XXX and 6XXX series aluminum alloys are the best for welding overall.
AA 5052 H32 is cold-rolled aluminium alloy having very high corrosion resistance with an industrial and marine environment, good formability, and good weldability out of other aluminium alloys and thus has been used for automotive and marine structural applications.
Aluminum 6063 is widely recognized for its weldability and heat treatability, as well as for its ability to resist corrosion.
6060 has excellent weldability by all standard methods including GMAW (MIG) and GTAW (TIG). Filler alloy 4043 is the primary filler though 5356 wire is the suggested alternative.
TIG Weld Seam
Aluminium is much more difficult because the material is surrounded by an oxide layer. This melts at a much higher temperature than the base metal. Therefore, the oxide layer needs to be removed or disturbed in order to produce an integral weld.
Article Revised July 28th, 2022. It's often said that aluminum is a more difficult metal to weld than steel. While it's true that most welders start out by learning to weld steel before moving on to aluminum, it's not entirely accurate to say that one is more difficult than the other.
No, aluminum 2024 is considered poor in weldability because of its tendency to suffer microcracking, which propagates under load and fatigue conditions.
Material thickness: Most reputable MIG machines can be used to weld aluminium down to 3mm thickness. To successfully weld materials thinner than 3mm, it may be neccessary to use specialist MIG or TIG welders with pulse capability. (Note: to TIG weld aluminium, you will need an "AC/DC" machine such as the 202T).
The author notes that four of the most difficult metals to weld are aluminum, cast iron, brass, and stainless steel.
Generally, two processes are used for aluminum welding: GTAW (TIG) and GMAW (MIG). Most welders in the business will say TIG is the better option for welding aluminum because it allows for better results on lighter gauge materials. When done correctly, TIG welding aluminum can produce quality welds.
Aluminum 6061-T6 has a higher yield strength and fatigue strength when compared to Aluminum 6063-T6. It has good extrudability, machinability and weldability along with good corrosion resistance – although it's less resistant than Aluminum 6063.
However, it should never be used to weld any of the 2XXX alloys or other alloys containing copper, such as 6013 or 6111 because the weld will very likely crack. Both 4043 and 5356 work well when welding 6XXX alloys.
A Comparison of 6063 and 6061 Aluminum Alloy
If strength is a primary consideration, 6061 may be the better choice. However, when it comes to surface quality, corrosion resistance and workability, 6063 performs better. Both these alloys are weldable, but it should be noted that 6061 is slightly more machinable.
Aluminum 5052 has a smoother finish than 6061, although it is not heat-treatable. Aluminum 5052 has a higher fatigue strength and modulus of elasticity than Aluminum 6061, making it an excellent forming alloy. Additional aluminum alloy 5052 characteristics include: Non-heat treatable.
The main difference between 5052 and 6061 aluminum is that 6061 is a heat-treatable alloy and therefore stronger than 5052 aluminum. 6061 also features high resistance to stress combined with good formability and weldability.
Yes. If this is for a salt water application you have to recognize the corrosion rate of two exposed dissimilar metals is much greater than for a single alloy of the same metal. Essentially, the two exposed alloys become a battery in in the presence of salt water.
The thickness of aluminum in industrial welding applications typically ranges from 1/8 inch to 16 gauge, but you may be welding up to 3/8 or 1/2 inch in some cases. Gas and filler metal selection, as well as proper technique, may differ depending on the material thickness and the goals of the application.
When compared to 6061 AL, 6063 aluminum has a higher melting temperature, higher thermal conductivity, and higher heat capacity. AL 6063 has a better surface finish than AL 6061 and is preferrable for architectural purposes.
7146 Note: Alloys 2024, 7075 and 7050 are considered non-weldable by the arc welding process. See page 9. This section presents a discussion about the properties, before and after welding, of heat treatable vs. non-heat treatable aluminum alloys.