Annex (iii)
STAINLESS STEEL
Stainless steels were first developed in the
early 20th century and are now an extremely versatile family of
engineering materials, which are selected primarily for their
corrosion and heat resistant properties. Stainless steels are
alloys of iron and carbon (<1.5%) containing a minimum of 10.5%
chromium. Whilst chromium is the primary alloying element and
is responsible for the intrinsic corrosion resistance of stainless
steels, nickel is the second most important alloying addition
helping determine the metallurgical structure, physical and mechanical
properties.
Stainless steels offer a broad range of properties.
They are corrosion resistant, weldable, and formable, provide
a variety of mechanical properties, can be magnetic or non-magnetic,
and are hygienic and visually attractive. Stainless steels are
long lasting and are fully recyclable at the end of their useful
life. This versatility has underpinned the development of the
stainless steel industry. During the past 90 years the use of
stainless steels has grown significantly, with an annual growth
since the early 1950's of 5% and total worldwide production reaching
22 million tonnes in 2003.
Stainless steels are now used in a wide variety
of applications. For example:
— In corrosive environments, including
the chemical, petrochemical and oil and gas industries.
— Stainless reinforcement bar provides
a long lasting alternative to traditional carbon steel rebar for
the construction industry.
— Where hygiene and cleanness are important,
such as the pharmaceutical industry, for food processing, catering
and hospital equipment and surgical implements and implants, stainless
steels are the first choice.
— Their mechanical properties can be
exploited to provide high strength and light weight, without compromising
their inherent corrosion resistance or formability, and are used
increasingly in such applications as car chassis components.
— The availability of a variety of
different surface finishes, including polished and patterned and
combined with their natural durability, has encouraged architects
and designers to use stainless steels for a range of building
applications such as external cladding, roofing and internal fixtures
and fittings.
Today, there are over 100 grades of stainless
steel that have been developed to provide the optimum combination
of properties, and cost, to meet the specific needs of this wide
range of markets.
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