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Aluminum Workshop: Alloys for furniture fabrication

Q: Which alloy would you recommend for cold bending aluminum tubing or fabricating aluminum law furniture?

A: First consider alloy availability. Many alloys are available as round tubing, but not all are obtainable. Most small-diameter tubing is extruded because it’s relatively economical to produce in this manner, but 5XXX alloys are difficult to extrude, so they’re not commonly available. Most 2XXX and 7XXX alloys aren’t really weldable and should be avoided. However, 7005 is the exception—it’s readily weldable but a bit difficult to bend. 4XXX alloys aren’t commonly available as extruded tubing.

That leaves 1XXX, 3XXX, and 6XXX alloys. More specifically, the alloys to consider, in order of increasing strength, are 1100-O, 3003-O, 6063-T4, 6063-T6, 6061-T4, and 6061-T6. All are easily weldable and can be bent. However, as a rule, the stronger the alloy, the more difficult it is to bend. In other words, everything else being equal, weaker alloys can be bent around a smaller radius than the stronger alloys.

The other factor to consider is the ratio of the tube diameter to its wall thickness. The larger this ratio becomes, the larger the minimum bend radius you can use.

In making furniture, you probably generally deal with 1-in.-dia. tubing with a 1/16-in. wall thickness. In this size, 1100-O tubing can be bent around a very small radius, but it may not be strong enough for the intended application. A stronger alloy, 3003-O typically can be bent around a radius 1.5 times the tubing diameter and would be a good choice. Stronger yet, 6061-T4 and 6063-T4 typically can be bent around a radius 2.5 times the tubing diameter. The strongest are 6061-T6 and 6063-T6; they require a minimum bend radius four times the tubing diameter.

About the Author
Aluminum Consulting Inc.

Frank Armao

President

Aluminum Consulting Inc.

440-479-0239

Frank Armao was an active member of the AWS D1 Committee, chairman of the AWS D1 Aluminum Subcommittee, and member of the Aluminum Association Committee on Welding and Joining. He also was the author of The WELDER's "Aluminum Workshop" column from 2001 to 2020.