Aluminium Design and Construction John Dwight

60 alloys, are:
BSEN.485 plate and sheet;
BSEN.755 extruded sections;
BSEN.754 drawn tube.
Figures 4.3 and 4.4 show compositions and minimum mechanical properties
for a representative range of aluminium materials, mainly based on the
above standards. Where a band is drawn, this shows the possible range
for the property concerned, depending on form and thickness.
Table 4.5 presents more specific data for a shortlist of alloys, covering
plate, sheet and extrusions. The strength of drawn tube can be estimated
by taking that for either equivalent work-hardened sheet material, or
else equivalent heat-treated extrusion material.
4.3.3 Comments on certain alloys
(a) 5xxx-series alloys
The A-rating for durability accorded to these alloys (Table 4.4) is usually
a true indication of their excellent corrosion resistance. However, when
such alloys have a magnesium content higher than about 3.5 or 4%, and
they are required to operate in a hot environment, there is a danger of
abnormal forms of corrosion (Section 4.7.1). For such applications, it is
desirable to keep the magnesium content down by using a weaker
alloy. For example, in the construction of welded tipper-truck bodies
one would normally select one of the strongest versions of 5xxx-series
alloy, such as 5083. But this alloy, with a nominal magnesium content
of 4.5%, becomes unacceptable if the body has to carry hot material. In
such a case, one should change to a weaker alloy with less magnesium.
The following 5xxx-series alloys, not covered in Table 4.5, also appear
in structural codes:
5052 (Mg 2.5, Cr 0.2) slightly stronger than 5251;
5754 (Mg 3.1) intermediate between 5251 and 5154A;
5454 (Mg 2.7, Mn 0.7, Cr 0.1) similar strength to 5154A.
(b) 6xxx-series alloys
As already explained, these alloys are broadly available in a stronger and
a weaker version. The latter with its superb extrudability is selected when
stiffness is the main criterion, the 6063 alloy being much used. For more
highly stressed situations, the stronger version becomes necessary,
popular alloys being 6082 in Britain, and 6061 in North America. The
6061 is not quite as strong as 6082, but is slightly better for forming. Other
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