Stainless
steels, such as
304, 304L 316, 316L, have higher resistance
to oxidation
(rust) and
corrosion in
many natural and man made environments, however, it is
important to select the correct type and grade of
stainless steel for the particular application.
High oxidation resistance
in air at
ambient temperature
is normally achieved with additions of more than 12% (by
weight) chromium.
The chromium forms a
passivation layer of
chromium(III) oxide
(Cr2O3) when exposed to
oxygen. The
layer is too thin to be visible, meaning the metal stays
shiny. It is, however, impervious to
water and
air, protecting the metal beneath. Also, when the
surface is scratched this layer quickly reforms. This
phenomenon is called
passivation by
materials scientists,
and is seen in other metals, such as
aluminium.
When stainless steel parts such as
nuts and
bolts are
forced together, the oxide layer can be scraped off
causing the parts to
weld together. When disassembled, the welded
material may be torn and pitted, an effect that is known
as galling.
Stainless
steel's resistance to
corrosion and staining, low
maintenance, relative inexpense, and
familiar luster make it an ideal base
material for a host of commercial
applications. There are over 150 grades
of stainless steel, of which fifteen are
most common. The alloy is
milled into sheets, plates, bars,
wire, and tubing to be used in
cookware,
cutlery,
hardware,
surgical instruments, major
appliances, industrial equipment,
and building material in
skyscrapers and large buildings.
The famous seven-story pinnacle of the
Chrysler Building in
New
York City is adorned with
gleaming stainless steel cladding.
Stainless
steel is 100%
recyclable. In fact, over 50% of
new stainless steel is made from
remelted scrap metal, rendering it a
somewhat eco-friendly material.
Flanges (stainless steel / Carbon steel)