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General
Information
The many unique values provided by stainless steel make it a
powerful candidate in materials selection. Engineers,
specifiers and designers often underestimate or overlook
these values because of what is viewed as the higher initial
cost of stainless steel. However, over the total life of a
project, stainless is often the best value option.
What is
Stainless Steel?
Stainless steel is essentially a low carbon steel which
contains chromium at 10% or more by weight. It is
this addition of chromium that gives the steel its unique
stainless, corrosion resisting properties.
The chromium content
of the steel allows the formation of a rough, adherent,
invisible, corrosion-resisting chromium oxide film on the
steel surface. If damaged mechanically or chemically, this
film is self-healing, providing that oxygen, even in very
small amounts, is present. The corrosion resistance and
other useful properties of the steel are enhanced by
increased chromium content and the addition of other
elements such as molybdenum, nickel and nitrogen.
There are more than
60 grades of stainless steel. However, the entire
group can be divided into five classes. Each is identified
by the alloying elements which affect their microstructure
and for which each is named.
Benefits of
Stainless Steel
8Corrosion
resistance
Lower alloyed grades resist corrosion in atmospheric and
pure water environments, while high-alloyed grades can
resist corrosion in most acids, alkaline solutions, and
chlorine bearing environments, properties which are utilized
in process plants.
8Fire
and heat resistance
Special high chromium and nickel-alloyed grades resist
scaling and retain strength at high temperatures.
8Hygiene
The easy cleaning ability of stainless makes it the first
choice for strict hygiene conditions, such as hospitals,
kitchens, abattoirs and other food processing plants.
8Aesthetic
appearance
The bright, easily maintained surface of stainless steel
provides a modern and attractive appearance.
8Strength-to-weight
advantage
The work-hardening property of austenitic grades, that
results in a significant strengthening of the material from
cold-working alone, and the high strength duplex grades,
allow reduced material thickness over conventional grades,
therefore cost savings.
8Ease
of fabrication
Modern steel-making techniques mean that stainless can be
cut, welded, formed, machined, and fabricated as readily as
traditional steels.
8Impact
resistance
The austenitic microstructure of the
300
series
provides high toughness, from elevated temperatures to far
below freezing, making these steels particularly suited to
cryogenic applications.
8Long
term value
When the total life cycle costs are considered, stainless is
often the least expensive material option |