Alloy 5554 is used for welding 5454 base
alloy, which also is used for high-temperature
applications. The Al-Si (4xxx series) filler
alloys may be used for some high-service-temperature applications, depending on
base alloy type and weld performance
requirements.
aluminum components and their applications. Keep in mind the type and chemistry
of the base material to be welded, as well as
the welded components’ performance
requirements. You can use an aluminum
filler alloy selection chart to assist in selecting
the most appropriate filler alloy. ■
Tony Anderson, C. Eng., is corporate technical
training manager for ESAB Welding & Cutting
Products and member of the Practical Welding
Today Advisory Board. He can be reached at 411
S. Ebenezer Road, Florence, SC 29501, 843-664-
5627, tanderson@esab.com, www.esabna.com.
No. 6: Postweld Heat
Treatment
The common heat-treatable base alloys,
such as 6061-T6, lose a substantial amount
of their mechanical strength after welding.
For example, 6061-T6 typically has 45,000-
PSI tensile strength prior to welding and
around 27,000 PSI in the as-welded condition. On occasion you may want to perform
postweld heat treatment to return the
mechanical strength to the manufactured
component. When postweld heat treating,
consider the filler alloy’s ability to respond
to the heat treatment.
Most commonly used filler alloys will not
respond to postweld heat treatment without
adequate dilution with the heat-treatable base
alloy. This is not always easy to achieve and
can be difficult to control consistently. For
this reason, filler alloys have been developed
to respond independently to heat treatment.
Filler alloy 4643, for example, was
specifically designed for welding 6xxx series
base alloys and producing high mechanical
properties in the postweld heat-treated
condition. It was developed by reducing the
silicon in the well-known alloy 4043 and
adding 0.10 percent to 0.30 percent
magnesium. A number of other heat-treatable filler alloys are available for welding
some of the 2xxx series alloys and some of
the heat-treatable cast aluminum alloys.
Successfully selecting the best filler alloy
can be achieved only after a full analysis of
the many variables associated with welding
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