Several types of factors affecting metal corrosion in hardware processing
Published on:
2021-02-22
There are many factors that cause corrosion of steel structures, mainly electrochemical corrosion. Once the steel structure corrodes, it will become more and more serious. In this way, the cross-sectional area of the component will be reduced, the bearing capacity will be reduced, and its use value will be gradually lost and scrapped. Although the corrosion of the steel structure currently in use is inevitable, the corrosion rate can be controlled, which requires effective anti-corrosion measures for the steel structure.
Characteristics of metal corrosion in hardware processing: After shot peening, press forming, electric welding, and assembly, the thermal stress distribution of the steel structure is uneven or the grains are deformed, which leads to the difference in the internal potential of the steel structure, which is the "hidden danger" of the corrosion of the steel structure, which is also the steel structure. The reason why electric welding is particularly prone to rust.
Metal corrosion is caused by various internal and external factors. In summary, there are five main factors that affect the corrosion of metal processing metals.
The influence of metal processing metal material itself
Different metal processing metals have different potentials and different metallographic structures, and their stability (that is, corrosion resistance) is different, and steels with the same chemical composition have different corrosion resistance due to different heat treatment processes. In addition, uneven distribution of thermal stress or grain deformation during thermal processing during forging, casting, welding, etc., may cause differences in the internal potential of the metal processing metal and accelerate the corrosion of the metal processing metal itself.
Metal processing metal surface finish state
There is also a significant effect on the corrosion rate. Especially in the early stage, the smoother the metal surface, the better the corrosion resistance. Rough metal processing metal surface, because the deep concave part is not easy to contact with oxygen, it becomes a positive electrode, and the surface becomes a negative electrode, causing the oxygen concentration difference battery to corrode.
Influence of ambient temperature
- Under normal circumstances, the corrosion rate of metalworking metals in electrolyte solutions increases with increasing temperature. For example, for every 10°C increase in seawater temperature, the corrosion rate of steel doubles because the electrical reaction increases as the temperature increases. In addition, in areas with continental climates, the temperature difference between day and night is large, and the relative humidity in the atmosphere at night rises again, so that the moisture in the air will condense on the surface of the metal processing metal in the form of condensation, providing conditions for the metal processing metal to rust. .
Effect of Solution Composition and Concentration
For example, seawater is a natural electrolyte solution containing various salts, which also contains organic matter, sludge, dissolved gas, decayed organic matter, etc. However, the important factors affecting the corrosion rate of steel are the salinity of seawater, high salinity, high electrical conductivity, corrosion current intensity of macroscopic cells, and corrosion of steel. In addition, a large amount of chloride ions in seawater will hinder or even destroy the passivation of metal processing metals and promote the corrosion of metal processing metals.
Influence of factors such as corrosive media
Various corrosive media and other factors will also accelerate the corrosion of metal processing metals. In addition to O2 and H2, the atmosphere also contains N2 and various impurities, such as salt spray near the ocean, SO2 and H2S in chemical industrial areas, as well as various soot, metal processing metal compounds and other salt particles. Once these corrosive media fall on the surface of the metal processing metal, they will condense with moisture and accelerate the corrosion of the metal processing metal.
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Sheet metal processing production process
2022-07-06
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