ssc-452 aluminum structure design and fabrication guide ship

Aluminum Marine Structure Guide
Figure 2-1 Stress-strain curve of 5083 aluminum compared to steel and FRP
(Beach et al., 1984).
2.1.4 Properties at Elevated Temperatures
Some aluminum alloys retain their strength, and even increase in strength, at very low
temperatures with little loss in ductility. For his reason, they are well suited for cryogenic
applications. However, aluminum alloys soften at higher temperatures, and therefore have poor
resistance to heating, especially in a shipboard fire. There is a common misconception that
aluminum will burn in a shipboard fire. However, because it will melt at about 1,100 O F (600
O C) structure involved in a fire will apparently disappear (reappearing in puddles of melted and
resolidified metal) giving the appearance of having burned.
The properties of some alloys at elevated temperature are given in Table 2-4 as provided in the
Aluminum Design Manual of The Aluminum Association (Aluminum Association, 2005). The
data is plotted in Figure 2-2. The Aluminum Association cautions that these data represent
averages for various sizes, product forms, and methods of manufacture, and are intended only as
a basis of comparing various alloys, and should not be used for design. Data is represented for
common alloys used in marine construction but not necessarily for the particular tempers of the
alloys that are used. However, the strength achieved by heat treatment or work hardening is lost
at higher temperatures, so all tempers of the same alloy approach the same strength properties
with increasing temperatures. Additional information on other alloys and tempers is available in
the Aluminum Design Manual.
2-4