Aluminium Design and Construction John Dwight

Figure 4.6 Variation of tensile stress (f u ) with temperature. Tested at temperature T after
long-term exposure at that temperature.
relevant temperature and then tested at that temperature [1]. The reason
for the room-temperature values not agreeing exactly with those given
previously is that they were obtained from typical material, whereas
the Section 4.3.2 data were based on specification minima. Figure 4.7
gives more comprehensive data for two of the alloys [13], from which
we see that the loss of strength at temperatures over 100°C is considerably
more pronounced with 6082 than it is with 5083. Weakening with
temperature is a significant factor in the design of supersonic aircraft,
and special high-strength alloys have been developed to reduce the
effect. One such alloy is 2618, which under prolonged heating at 200°C
has twice the strength of 2014A (in the T6 temper).
Also of interest is the decrease in strength after a relatively shortterm
exposure to elevated temperature (Figure 4.8). This is relevant to
the fire-rating of buildings and other structures.
4.3.6 Properties of forgings
Aluminium forgings range in size from small components, such as
the hinges, etc., on truck bodies, to the main members forming the
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