Aluminium Design and Construction John Dwight

1.1.3 The industrial metal
It is only since 1886 that aluminium has been a serious industrial metal,
that being the year when the modern smelting process was invented. It
has thus been available for a very short time, compared to the thousands
of years that we have had bronze, copper, lead, iron, etc. Today it easily
leads the non-ferrous metals in volume usage. It is selected in preference
to steel in those areas where its special properties (‘light and bright’)
make it worth paying for. There are many applications where aluminium
has found its rightful niche, and others where it is still on the way in.
Current world consumption is some 20 million tonnes per year.
1.1.4 Alloys
Pure aluminium is weak, with a tensile strength ranging from about 90
to 140 N/mm2 depending on the temper. It is employed for electrical
conductors and for domestic products (such as pans, cans, packaging),
but for serious structural use it has to be strengthened by alloying. The
strongest alloys have a tensile strength of over 500 N/mm2 .
There are around ten basic alloys in which wrought material (plate,
sheet, sections) is produced. Unfortunately, each of these alloys appears
in a vast range of different versions, so that the full list of actual
specifications is long. The newcomer therefore finds material selection
less simple that it is in structural steel, and there is also the alloy numbering
system to contend with.
In engineering parlance the term aluminium (or aluminum) covers
any aluminium-based material, and embraces the alloys as well as the
pure metal. To refer specifically to the pure or commercially pure material,
one has to say ‘pure aluminium’.
1.1.5 Castings
Aluminium is eminently suitable for casting. For larger items (such as
sand-castings), aluminium is often a preferred option to cast iron. For
smaller items (such as dye-castings), it provides a strong alternative to
zinc. A wide range of casting alloys is available, different from the wrought
alloys. The reliability that is possible with aluminium castings is
demonstrated by the fact that they have become standard for car wheels.
1.1.6 Supposed health risk
For many years it was believed that aluminium was entirely non-toxic,
and superior in this respect to most other metals. In the 1980s this
picture was reversed when researchers claimed to show that the prolonged
use of aluminium saucepans could cause minute amounts of the metal
Copyright 1999 by Taylor & Francis Group. All Rights Reserved.