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The process of making steel stainless and some of its general

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    هانى شرف الدين
    هانى شرف الدين غير متواجد حالياً

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     وسام الشكر

      وسام كبار الشخصيات


    تاريخ التسجيل: Nov 2005
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    The process of making steel stainless and some of its general

    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
    .

  2. [2]
    yehia samir
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    عضو فعال


    تاريخ التسجيل: Dec 2006
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