Seamless steel pipe corrosion resistance classification and
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Seamless steel pipe corrosion resistance classification and meaning
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No.
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Name
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Amount of symbols
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Unit symbol
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Meaning
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A
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Corrosion resistance
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The corrosion resistance refers to the metal material to resist the corrosive effects of the surrounding medium (air, water vapor, harmful gas, acid, alkali, salt, etc.) ability.The corrosion resistance of the metal is related to many factors, such as the chemical composition of the metal, the processing properties, the heat treatment conditions, the organization of the state, and the medium and temperature, etc. | |||
| Chemical corrosion | The chemical etching is a metal with the surrounding medium is directly a result of chemical action. It includes two forms of gas corrosion and the corrosion of the metal in the non-electrolyte. Which is characterized by: the corrosion process does not produce current; corrosion products deposited on the metal surface | ||||
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1
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Electrochemical corrosion
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Metals with acids, alkalis, salts, etc. occurs when the electrolyte solution contacting a caused by the action of etching, referred to as electrochemical corrosion. It is characterized by the current generated in the corrosion process, the corrosion product (rust) are not covered on the surface of the metal as an anode, but at a certain distance from the anode metal. | |
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2
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General corrosion
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Such corrosion is evenly distributed throughout the metal inner and outer surface, so that a cross-sectional continue to decrease, and ultimately make the force member destruction | |
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3
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Intergranular corrosion
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Such corrosion along the grain boundaries in the metal internal, generally does not cause any changes in the metal shape, tend to make the equipment or parts sudden destruction | |
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4
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Pitting corrosion
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Such corrosion concentrated in a small area of metal surface, and quickly to the depths of the development, and finally penetrate the metal, are a danger to the larger corrosion damage | |
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5
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Stress corrosion
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Means in the static stress (inside and outside the metal stress) under the action of the metal in the corrosive medium caused by the destruction of.It is also a transgranular corrosion damage caused by this corrosion medium listen | |
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6
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Corrosion fatigue
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Alternating stress caused by metals in corrosive media destruction. It is also a transgranular corrosion | |
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7
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Corrosion rate
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mg / (dm 2 · d ) or g / (dm 2 · d )
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The unit area of the metal material in the unit time by the weight loss after etching, referred to as etching rate | |
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8
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Corrosion rate
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R
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mm / a
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Etched off depth of the material by the metal material in a unit time is called the rate of corrosion www.sdcxf.com |
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