Stainless steel has excellent characteristics such as unique strength, high wear resistance, superior corrosion resistance and resistance to rust. Therefore, it is widely used in the chemical industry, food machinery, electromechanical industry, household appliance industry and home decoration, finishing industry.
The application and development prospects of stainless steel will become wider and wider, but the application and development of stainless steel largely determines the degree of development of its surface treatment technology.
Common types of stainless steel
1. Stainless steel varieties
(1) The main components of stainless steel: generally contain high-quality metal elements such as chromium (Cr), nickel (Ni), molybdenum (Mo), and titanium (Ti).
(2) Common stainless steel: chromium stainless steel, containing Cr≥12%; nickel-chromium stainless steel, containing Cr≥18%, containing Ni≥12%.
(3) Classification from the metallographic structure of stainless steel: There are austenitic stainless steels, such as: 1Cr18Ni9Ti, 1Cr18Ni11Nb, Cr18Mn8Ni5. Martensitic stainless steel, such as: Cr17, Cr28, etc. Generally called non-magnetic stainless steel and magnetic stainless steel.
Commonly used stainless steel surface treatment techniques have the following treatment methods:
1. Whitening of the natural color on the surface;
2. Surface mirror bright treatment;
3. Surface coloring treatment. In the process of processing stainless steel with natural surface whitening treatment, black oxide scale is produced after coiling, binding, welding or artificial surface heating treatment. This hard gray-black oxide scale is mainly composed of NiCr2O4 and NiF, two EO4 components. In the past, hydrofluoric acid and nitric acid were generally used for strong corrosion. However, this method is costly, pollutes the environment, is harmful to the human body, and is highly corrosive, and is gradually eliminated. At present, there are mainly two kinds of oxide scale treatment methods: ⑴ Sandblasting (pill) method: mainly adopts the method of spraying micro glass beads to remove the black oxide scale on the surface. ⑵ Chemical method: Use a non-polluting pickling passivation paste and a non-toxic cleaning solution with inorganic additives at room temperature for immersion. So as to achieve the purpose of whitening treatment of the natural color of stainless steel. After processing, it basically looks like a dull color. This method is more suitable for large and complex products. According to the complexity of stainless steel products and the different requirements of users, the mirror-bright treatment method of stainless steel surface can be achieved by mechanical polishing, chemical polishing, electrochemical polishing and other methods to achieve mirror gloss.