STAINLESS STEEL
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
Corrosion 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.
Fire and heat resistance
Special high chromium and nickel-alloyed grades resist scaling and retain strength
at high temperatures.
Hygiene
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.
Aesthetic appearance
The bright, easily maintained surface of stainless steel provides a modern and
attractive appearance.
Strength-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.
Ease of fabrication
Modern steel-making techniques mean that stainless can be cut, welded, formed,
machined, and fabricated as readily as traditional steels.
Impact 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.
Long term value
When the total life cycle costs are considered, stainless is often the least
expensive material option.
Cycle of Stainless Steel
To ensure a high quality of life, the materials that we use as consumers and
manufacturers should meet not only technical performance standards, but have
a Long Service Life, be Usable in a Great Number of Applications, and be Environmentally
Friendly. Once their service is complete, they should be 100% Recyclable, thereby
completing the life cycle to be used once again. Stainless Steel is such a material.
The longevity of stainless is the result of the alloying composition and, therefore,
it has a natural corrosion resistance. Nothing is applied to the surface that
could add additional material to the environment. It does not need additional
systems to protect the base metal, the metal itself will last.
Stainless steel needs less maintenance and its hygienic qualities means that
we do not have to use harsh cleaners to get a clean surface. There is little
or nothing to dump into the drain that could have an environmental impact.
Stainless steel products complete their service life. There is less concern
about disposal since this material is 100% recyclable. In fact, over 50% of
new stainless steel comes from old remelted stainless steel scrap, thereby completing
the full life cycle.
