Aluminum, like steel, can be produced with many different physical and chemical properties. Some grades react well to welding. Others require more expertise or shouldn't be welded at all. So, how do you choose the best aluminum for welding?
First off, know that aluminum is generally more difficult to work with than carbon steel or stainless steel. It behaves much differently -- usually fussier.
Here are the problems that aluminum typically presents when welding:
Since aluminum is relatively expensive, you’ll waste a lot of money by specifying a grade with low weldability.
Despite this, aluminum is still the material of choice for many engineers. It’s light, which makes it ideal for many applications. Since it’s a nonferrous metal, aluminum is also less corrosive and won’t rust (although it still corrodes in its own way -- just more slowly).
When you do decide on your aluminum grade, use a commonly produced aluminum grade for maximum cost-effectiveness. If there’s a lot of supply in the market, you’ll get a much better price.
When you buy “aluminum,” you’re actually buying an aluminum alloy -- there are other metals in there, too. Those other metals give the aluminum properties that vary by grade.
The grades are separated into series, beginning with 1XXX and ending with 7XXX. Generally, higher numbers mean a higher percentage of magnesium.
APPLICATION |
RECOMMENDED ALUMINUM GRADES
|
||||
Aircraft (structural, tube) | 2014 | 2024 | 5052 | 6061 | 7075 |
Architecture |
3003 | 6061 | 6063 | ||
Auto -- parts | 2014 | 2024 | |||
Auto -- frames & trailers | 2024 | 5052 | 6061 | 6063 | |
Boats | 5052 | 6061 | |||
Building products | 6061 | 6063 | |||
Chemical equipment | 1100 | 6061 | |||
Construction | 2024 | 6061 | 7075 | ||
Cooking utensils | 3003 | 5052 | |||
Drawn & spun parts | 1100 | 3003 | |||
Electrical | 6061 | 6063 | |||
Fasteners & fittings | 2024 | 6061 | |||
General fabrication | 1100 | 3003 | 5052 | 6061 | |
Machined parts | 2011 | 2014 | |||
Marine | 5052 | 6061 | 6063 | ||
Piping | 6061 | 6063 | |||
Pressure vessels | 3003 | 5052 | |||
Recreation equipment | 6061 | 6063 | |||
Screw machine products | 2011 | 2024 | |||
Sheet metal work | 1100 | 3003 | 5050 | 5052 | 6061 |
Storage tanks | 3003 | 6061 | 6063 |
The series that hold up best to welding are 5XXX and 6XXX. "Is 6061 aluminum weldable?" is one of the most frequent questions we get. We most often use 5050 or 6061 aluminum, so the answer is "Definitely." Those two metals are very common, so availability and price shouldn’t be an issue.
Why these alloys? They’re the most forgiving. They have a lower level of magnesium, aren’t as thick, and are less likely to crack.
Depending on your project, these other alloys may be suitable:
5XXX and 6XXX series aluminum alloys are the best for welding overall. Remember that your project and application will ultimately determine which grade will work best.
With so many aluminum types to choose from, it’s best if you partner with a vendor in the design phase who knows all their pros and cons. And don’t forget to pick an appropriate filler metal -- you might be able to save some money!
(Editor's note: This article was originally posted in September 2017 and was recently updated.)