# The process of making steel stainless and some of its general



## هانى شرف الدين (17 يوليو 2008)

We have grown up hearing about stainless steel our whole lives. But
how many people actually know what it really is? Let us take a
look at the process of making steel stainless and some of its general
applications.

English metallurgist Harry Brearley invented stainless steel in 1912
while he was researching alloys to protect cannons from erosion. The
first commercial production of stainless steel occurred in August 1913.
A few years later, stainless steel played a key role in building valves
for aircraft engines during World War I. By the 1920fs, people
were finding myriad uses for stainless steel in America. Most famously,
the seven arches on top of the Chrysler Building in New York City were
clad in stainless steel in 1929.

Chemically speaking, stainless steel is defined as an iron and carbon
alloy with a minimum of 11.5 percent chromium . Its name
indicates some of its properties, because it does not stain or rust as
easily as ordinary steel. It is also sometimes referred to as corrosion
resistant steel. It should not be confused with galvanized steel.
Galvanized steel is dipped into zinc to prevent corrosion. Galvanized
steel is created when the zinc goes through a reaction with the iron
molecules. The most external layer is all zinc, but successive layers
are a mixture of zinc and iron, with an interior of pure steel in
galvanized steel.

Manganese is often found in many stainless steel compositions. Manganese
preserves an austenitic structure in the steel akin to nickel, and it is
less expensive. Austenitic stainless steel makes up about 70 percent of
the world�f�fs overall stainless steel production. Super
austenitic stainless steels have high molybdenum and nitrogen
additions, as well as higher nickel. Because of these additions,
they have a tremendous resistance to chloride pitting and crevice
corrosion. Other types of stainless steel include martenistic, ferritic
and duplex, all of which have different compositions and strengths
suited to various applications.

When its composition is 18 percent manganese and 10 percent nickel, it
is often referred to as 18/10 stainless steel, which is often used in
high-quality flatware. There are many different grades and surface
finishes of stainless steel, which makes the material very adaptable to
numerous applications. Look at the watch on your wrist. It�f�fs
likely made from stainless steel. It is also to make airplanes, surgical
appliances, building materials, cookware, cutlery, hardware, cars and
jewelry.

Mill finishes can be applied to flat rolled stainless steel with the use
of mechanical abrasives and the rollers themselves. After it is rolled
to size and annealed, oxidation is removed and the passivation layer is
made on its surface. At this time, a final finish can be added to
enhance the appearance of the steel.

For example, a sheet may have a matte finish to it, where the face of
the material is abrasively polished leaving a clean but dull sheen to
the surface. This is often desired where the material will be used in a
high visibility, high use location; the surface will not show scratches
and scars as readily as a highly polished finish.

Stainless steel is available in both hot rolled steel sheets and cold
rolled steel sheets, and it can also be obtained in plates, rolls,
strips, foil and bars​.​


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## yehia samir (29 يوليو 2008)

جزاك الله خيراً


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