There are many kinds of surface treatment processes for stainless steel, such as electroplating, anodizing, sandblasting, painting, passivation, pickling, degreasing, rust removal and so on. This paper mainly introduces three common surface treatment processes of stainless steel, i.e. passivation, pickling and degreasing.
1. Passivation of stainless steel
The recommended surface of this process must be iron free. The presence of stainless steel particles on the surface of any iron, cast iron, low carbon steel, medium carbon steel or low alloy steel will promote pitting corrosion of “free” iron and stainless steel on its surface. This is a very serious problem, so passivation is used only for stainless steel and stainless steel. The main purpose of stainless steel passivation is to prevent oxidation and corrosion of stainless steel surface.
2. Stainless steel pickling.
The purpose of pickling of stainless steel is to remove the oxide coating on the surface of stainless steel after high temperature welding, heat treatment or hot working. At the same time, steel or iron or steel particulate pollutants corroded by red rust can also be eliminated. Please note that if there is no acid solution to clean the surface after pickling, the surface will soon begin to rust and corrode. The corrosion resistance of the steel surface layer is reduced.
Stainless steel pickling process can be applied to all 200, 300, 400 series of stainless steel surface treatment. All pickling operations result in the removal of impurities from the metal surface with a slight change in size, so the result is a degree of extinction of visual brightness that may also be a significant reduction in size.
Heat treatment in vacuum or a good controlled atmosphere, such as bright annealing, eliminates the need for pickling, which usually results in a better finish for stainless steel.
3. Degreasing and degreasing of stainless steel detergent.
Before any surface treatment of stainless steel, grease, cutting fluid, drawing compounds and other lubricants must be removed before surface heat treatment of stainless steel parts or final passivation treatment. Stainless steel parts must also be further welded before degreasing to prevent carbon from pickup at high temperatures.
Usually, stainless steel cleaning agent is selected. It only needs room temperature soaking for 1-8 minutes to remove any oil stains. It is easy to operate and has low labor intensity. It can be reused repeatedly and the cost of production can be reduced effectively. In cleaning operations with other metals, cleanliness can be increased through the use of brushing, spraying or stirring operations.
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