What are the common surface treatment processes for stainless steel

There are many kinds of surface treatment processes for stainless steel, such as electroplating, anodic oxidation, sandblasting, painting, passivation, pickling, degreasing, rust removal and so on. This paper mainly introduces three common surface treatment processes of stainless steel, including passivation, pickling and degreasing, for the reference of friends in need:

1. Stainless steel passivation

The recommended surface for 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 only used to treat stainless steel and stainless steel. The main purpose of stainless steel passivation is to prevent stainless steel surface oxidation and corrosion.

2. Stainless steel pickling

The purpose of stainless steel pickling treatment is to remove oxide scales on the surface of stainless steel after high temperature welding, heat treatment or hot working. At the same time, it can eliminate the contamination of steel or iron or steel particles which are corroded by red rust. Please note that if there is no acid solution to clean the surface after pickling, the surface will start to rust and corrode soon. The corrosion resistance of the steel surface layer below 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 on the metal surface with a slight change in size, so the result is that to some extent an extinction of visual brightness 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, and usually gives stainless steel a better finish.

3. Degreasing and degreasing of stainless steel cleaning agent

The pretreatment of any process of stainless steel surface treatment must first remove grease, cutting fluid, paint compounds and other lubricants, etc. before the surface heat treatment of stainless steel parts or the final passivation treatment can be carried out. Stainless steel parts must also be further welded before degreasing to prevent pickup carbon at high temperatures.

Usually, stainless steel cleaning agent is chosen. It only needs 1-8 minutes to soak at room temperature to remove any oil pollution. It is easy to operate and has low labor intensity. It can be reused repeatedly and effectively reduce the cost of production. In cleaning operations with other metals, the cleanliness rate can be increased through the use of brushing, spraying or stirring operations.