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WHAT IS
STAINLESS STEEL?
Stainless
steel is an alloy of iron and carbon with a 10 % minimum chromium
content (generally in a range between %12 and 20). Chromium provides
durability and resistance to the material against corrosion and
heat. Some other elements may also be added into the alloy in order
to obtain special quality stainless steel types.
The most important type among such special stainless steel types is
the 18-8 graded stainless steel which is prepared by adding nickel
(18 percentage chromium and 8 percentage nickel). The other major
components added into stainless steel are niobium, manganese,
molybdenum, phosphor, selenium, silicon, sulfur, titanium and
zircon. These alloys are all prepared in electrical stoves within
long periods in consequence of the fact that high temperatures and
sensitive chemical inspection are required in the production of
stainless steel.
In this method, the stoves are loaded with scrap materials which
contain the elements to be included in the final product. In the
recent times, a technique has been developed based on initially
melting the materials in an electrical furnace, and then processing
with oxygen in another pot. In order to normalize the reaction, the
oxygen gas which is diluted by argon is pulverized either by the
welding torch from above or through a hole at the bottom of the pot.
Stainless steels can be classified according to their chemical
compositions and reaction to thermal processing: ferrite steels that
can not be hardened, and which contain 15-30 percent chromium, and
less than 0,2 percent carbon; martensite steels that can be hardened
by means of quenching, and which contain 10-18 percent chromium,
and carbon in variable percentages (more than 1 percent in some
alloys); austenite steels which contain 16-26 percent chromium, 6-22
percent nickel, and less than 0,25 percent carbon. Austenite steels
which can be hardened without quenching, are most resistant
materials against abrasion. |