1、Production process reasons: This is one of the reasons for the oxidation of steel products. In terms of production process and product characteristics, forming a thin oxide film on the surface of the product is the basic process to avoid oxidation, and it is also the difference between steel products. One of the main characteristics of other steel products, but when the oxide film is incomplete or discontinuous due to insufficient or negligent production technology, the oxygen in the air will directly react with some elements in the product, resulting in the appearance of the product. show oxidation.
2、Reasons for product composition ratio: In order to reduce production costs, some manufacturers reduce the proportion of some important elements such as chromium and nickel, and increase the content of other elements such as carbon. The production phenomenon of the composition ratio not only greatly reduces the quality of the product, for example, when the content of chromium element in the 304 stainless steel tube is insufficient, it not only affects the corrosion resistance and formability of the product, but also has potential potential when used in the chemical industry, equipment and production industries. At the same time, it also affects the appearance and antioxidant properties of the product.
3、Artificial reasons: This is also one of the most common reasons for product oxidation that some consumers encounter when using stainless steel products. Some consumers operate improperly in product use and maintenance, especially some stainless steel pipe products used in the food chemical equipment industry. The probability of oxidation is high. For man-made oxidation of steel products, it is necessary to have correct product use knowledge and regular and effective maintenance and maintenance, so as to reduce the oxidation caused by improper use.
Stainless steel relies on a very thin, firm, fine and stable chromium-rich oxide film (protective film) formed on its surface to prevent the continuous infiltration and oxidation of oxygen atoms to obtain the ability to resist rust. Once for some reason, this film is continuously damaged, oxygen atoms in the air or liquid will continue to infiltrate or iron atoms in the metal will continue to separate out, forming loose iron oxide, and the metal surface will be continuously corroded. There are many forms of damage to this surface film, the most common in daily life are the following:
1. On the surface of stainless steel, dust containing other metal elements or attachments of heterogeneous metal particles accumulate. In humid air, the condensed water between the attachments and the stainless steel connects the two into a micro-battery, which triggers an electrochemical reaction and protects the stainless steel. The film is damaged, which is called electrochemical corrosion.
2. The surface of stainless steel adheres to organic juices (such as vegetables, noodle soup, etc.), and in the presence of water and oxygen, organic acids are formed, and organic acids will corrode the metal surface for a long time.
3. The surface of stainless steel adheres to contain acids, alkalis and salts (such as alkali water and lime water splashing from the decoration walls), causing local corrosion.
4. In polluted air (such as the atmosphere containing a large amount of sulfide, carbon oxide, nitrogen oxide), when encountering condensed water, it forms liquid spots of sulfuric acid, nitric acid and acetic acid, causing chemical corrosion.
The above conditions can cause damage to the protective film on the stainless steel surface and cause rust. Therefore, to ensure that the metal surface is permanently bright and not rusted, we recommend:
1. The surface of stainless steel products must be cleaned and scrubbed frequently to remove attachments and eliminate external factors that cause modification;
2. keep the environment dry;
3. The chemical composition of some stainless steel pipes on the market cannot meet the corresponding national standards and cannot meet the material requirements. Therefore, it will also cause rust, which requires users to carefully choose products from reputable manufacturers.
Stainless steel has the ability to resist atmospheric oxidation—that is, rust resistance, and it also has the ability to corrode in media containing acids, alkalis, and salts—that is, corrosion resistance. However, the size of its anti-corrosion ability varies with the chemical composition of its steel itself, the state of mutual addition, the conditions of use and the type of environmental media. For example, 304 steel pipe has absolutely excellent anti-corrosion ability in a dry and clean atmosphere, but if it is moved to a seaside area, it will quickly oxidize in the sea fog containing a lot of salt, while 316 steel pipe performs well. Therefore, it is not any kind of stainless steel that can resist corrosion and rust in any environment.
Post time: Apr-17-2023