1. Oil and grease
Organic substances such as oil, grease and even fingerprints can become a source of local corrosion. Because these substances can act as a barrier, they will affect the chemical and electrochemical cleaning effect, so they must be thoroughly cleaned up. ASTM A380 has a simple WATERBREAK test to detect organic pollutants. During the test, water was poured from the top of the vertical surface. During the downward flow, the water would separate around the organic matter. Flux and/or acid chemical cleaning agent can remove oil stains and grease.
2. Residual adhesive
When the tape and protective paper are removed, a part of the adhesive will always remain on the surface of the stainless steel. If the adhesive is not hard, it can be removed with an organic flux. However, when exposed to light and/or air, the adhesive hardens and forms a source of crevice corrosion. Then it needs to be cleaned mechanically with fine abrasives.
3. Paint, chalk and marking pen print
The effects of these pollutants are similar to the effects of oil and grease. It is recommended to use a clean brush and clean water or alkaline cleaning agent for washing. You can also use high-pressure water or steam to rinse.
The stainless steel whose structure is mainly ferrite in use. The chromium content is between 11% and 30%, and it has a body-centered cubic crystal structure. This kind of steel generally does not contain nickel, and sometimes also contains a small amount of Mo, Ti, Nb and other elements. This kind of steel has the characteristics of large thermal conductivity, small expansion coefficient, good oxidation resistance, and excellent stress corrosion resistance. It is mostly used to make atmospheric resistance. , Water vapor, water and oxidizing acid corroded parts. This type of steel has disadvantages such as poor plasticity, significantly reduced plasticity and corrosion resistance after welding, which limits its application. The application of out-of-furnace refining technology (AOD or VOD) can greatly reduce interstitial elements such as carbon and nitrogen, so this type of steel is widely used.
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