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27

Technical Services

One of the most frequently asked aluminum welding questions is “What filler alloy do I use for welding 6061?”.

The AlcoTec filler alloy chart has several suggested options of filler alloys to use with 6061. From a chemistry stand point,

there are very few options that are not acceptable. However, there are a few elements to consider when choosing the most

appropriate filler alloy to use.

1.

Ease of welding

- this is the relative freedom from weld cracking. By use of hot cracking sensitivity curves

(see page 25) for the various aluminum alloys, and through the consideration of dilution between filler alloy and

base alloy, we can establish the filler alloy/base alloy crack sensitivity rating.

2.

Strength of welded joint

- consideration of the tensile strength of groove welds and shear strength of fillet welds,

when welded with different filler alloys, can prove to be extremely important during welding design. Different filler

alloys, which may exceed the as-welded tensile strength of the base material, can be significantly different in

shear strength performance.

3.

Ductility

- a consideration if forming operations are to be used during fabrication, and may also be a design

consideration of service if fatigue and/or shock loading are of importance.

4.

Corrosion resistance

- a consideration for some environmental conditions and are typically based on exposure

to fresh and salt water.

5.

Sustained temperature services

- the reaction of some filler alloys at sustained elevated temperature (above 150°F).

This may promote premature component failure due to stress corrosion cracking.

6.

Color match

- base alloy and filler alloy color match after anodizing can be of major concern in some cosmetic applications.

7.

Post weld heat treatment

- the ability of the filler alloy to respond to post weld heat treatment associated with filler

alloy chemistry and joint design.

These are all elements that must be considered when selecting a filler alloy for welding on 6061. It is the application of the

completed weldment that will drive which alloy should be used for welding.

Filler Alloy for Welding 6061-T6

Color Match After Clear Anodize

6061 6061

6061

6061

Welded with 4043

Base Metal: 6061

Welded with 5356