Chemical polishing is a common surface treatment process for stainless steel. Compared with electrochemical polishing process, its biggest advantage is that it does not need DC power supply and special fixture, and can polish complex parts with high productivity.
As far as functionality is concerned, chemical polishing can not only obtain a surface with physical and chemical cleanliness, but also remove the mechanical damage layer and stress layer on the stainless steel surface to obtain a surface with mechanical cleanliness, which is beneficial to prevent local corrosion of parts, improve mechanical strength and prolong the service life of parts.
Since the patent of chemical polishing of stainless steel was issued in the early 1940s, many formulations have been disclosed so far, but it is still difficult for people to apply them in practice. Because there are many kinds of stainless steel, different brands of stainless steel have different corrosion laws, and it is impossible to use the same solution, so there are many kinds of chemical polishing solutions for stainless steel.
Extended data
Stainless steel is usually divided into martensite steel, ferrite steel, austenite steel, austenite-ferrite (duplex) stainless steel and precipitation hardening stainless steel. In addition, it can also be divided into chromium stainless steel, chromium nickel stainless steel and chromium manganese nitrogen stainless steel. And stainless steel for pressure vessels.
Carbon steel, ferritic stainless steel and martensitic stainless steel are magnetic, while austenitic stainless steel is non-magnetic, but they will be magnetic when martensitic transformation occurs during cold working and hardening. Heat treatment can be used to eliminate this martensite structure and restore its non-magnetism.
Ferritic stainless steel contains 15% ~ 30% chromium. Its corrosion resistance, toughness and weldability increase with the increase of chromium content, and its chloride stress corrosion resistance is better than other kinds of stainless steel. Ferritic stainless steel has good corrosion resistance and oxidation resistance because of its high chromium content, but its mechanical properties and technological properties are poor, so it is mostly used in acid-resistant structures with less stress and as oxidation-resistant steel.
This kind of steel can resist the corrosion of atmosphere, nitric acid and brine solution, and has the characteristics of good oxidation resistance at high temperature and small thermal expansion coefficient. It can be used in nitric acid and food factory equipment, and can also be used to manufacture parts that work at high temperature, such as gas turbine parts.
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