Summary of the basic types of stainless steel surface processing

The multiple surface processing of stainless steel broadens its application fields. Different surface processing makes the surface of stainless steel different, making it unique in its application. In the field of construction applications, the surface processing of stainless steel is important for many reasons.
1. The basic types of surface processing

There are roughly five types of surface processing that can be used for stainless steel, and they can be combined to transform into more final products.

The five categories are:

1. Rolling surface processing

2. Mechanical surface processing

3. Chemical surface processing

4. Textured surface processing and color surface processing

There are also some special surface processing, but no matter which surface processing is specified, the following steps should be followed:

1. Negotiate the required surface processing together with the manufacturer, and it is best to prepare a sample as the standard for mass production in the future.

2. When using a large area, such as a composite board, it must be ensured that the base coil or coil used is the same batch.

3. The production process should be considered when selecting the surface processing. For example, in order to remove the weld bead, the weld may have to be ground and the original surface processing must be restored. The tread plate is difficult or even unable to meet this requirement.

4. For some surface processing, grinding or polishing, the texture is directional, which is called unidirectional. If you make this pattern vertical instead of horizontal when used, dirt will not stick to it easily and it will be easy to clean.
2. Rolling surface processing

There are three basic rolling surface finishes for plates and strips, which are represented by the production process of plates and strips.

No.1: After hot rolling, annealing, pickling and descaling. The surface of the treated steel plate is a dull surface, a bit rough.

No.2D: It has a better surface finish than N0.1, and it is also a dull surface. After cold rolling, annealing, descaling, and finally light rolling with a matt roller.

No.2B: This is the most commonly used in construction applications. Except for the last mild cold rolling with a polishing roll after annealing and descaling, the other processes are the same as 2D, the surface is slightly shiny, and it can be polished.

No.2B Bright Annealing: This is a reflective surface, which is rolled by polishing rollers and is finally annealed in a controlled atmosphere. Bright annealing still maintains its reflective surface and does not produce oxide scale. Since no oxidation reaction occurs during the bright annealing process, no pickling and passivation treatments are required.
3. Polished surface processing

No. 3: Represented by 3A and 3B. 3A: The surface is uniformly ground, and the abrasive grain size is 80-100. 3B: The rough surface is polished, and the surface has uniform straight lines. It is usually made by polishing with an abrasive belt with a grain size of 180 to 200 on a 2A or 2B plate at one time.

No.4: One-way surface processing, low reflectivity, this surface processing may be the most widely used in architectural applications. The process steps are first polishing with coarse abrasives, and finally grinding with abrasives with a particle size of 180.

No.6: It is a further improvement of No.4, which is to polish the surface of No.4 with Tampico polishing brush in abrasive and oil medium. This surface finish is not included in “British Standard 1449″, but it can be found in American Standards.

No.7: It is called bright polishing, which is to polish the surface that has been ground very fine but still has abrasion marks. Usually used is 2A or 2B board, with fiber or cloth polishing wheel and corresponding polishing paste.

No.8: Mirror polished surface, high reflectivity, usually called mirror surface processing, because it reflects very clear images. Polish the stainless steel continuously with a fine abrasive, and then polish it with a very fine polishing paste. In architectural applications, it should be noted that this surface will leave fingerprints if it is used in places where there is a large flow of people or people often touch. Handprints can of course be wiped off, but they sometimes affect the appearance.
Four, surface roughness

The classification of rolled surface processing and polished surface processing is an indication of the degree that can be achieved, and another effective way to express it is to measure surface roughness. The standard measurement method is called CLA (Centerline Average). The measuring instrument moves laterally on the surface of the steel plate and records the peak and valley changes. The smaller the CLA number, the smoother the surface. The final results of different grades can be seen from the surface finish and CLA number in the table below.
Five, mechanical polishing

Note: We should remember that the grinding with sandpaper or belt in the grinding operation is basically a polishing and cutting operation, leaving very fine lines on the surface of the steel plate. We have had trouble using alumina as an abrasive, partly because of pressure issues. Any grinding parts of the equipment, such as abrasive belts and grinding wheels, must not be used for other non-stainless steel materials before use. Because this will contaminate the stainless steel surface.
Six, electrolytic polishing

This is a metal removal process in which stainless steel is used as the anode in the electrolyte, and the metal is removed from the surface after power is applied. This process is usually used for the processing of parts, because their shape is difficult to polish with traditional methods. The process is often used on the surface of cold-rolled steel sheet because its surface is smoother than that of hot-rolled steel sheet. However, electrolytic polishing will make the surface impurities more obvious, especially the titanium and niobium stabilized materials will cause differences in the weld zone due to particulate impurities.

Small weld scars and sharp edges can be removed by this process. This process focuses on the protruding parts on the surface and preferentially dissolves them. The electrolytic polishing process involves immersing stainless steel in a heated liquid. The ratio of the liquid involves many proprietary and patented technologies. The electrolytic polishing effect of austenitic stainless steel is very good.
7. Reticulated surface processing

There are many types of patterns that can be used in stainless steel. The advantages of adding patterns or netting surface processing to the steel plate are as follows:

1) Reduce “oil can-ning” (oil can-ning), which is a term used to describe the surface of bright material, which is not flat from an optical point of view. For example, for large-area decorative panels, even after stretching straightening or tension straightening, it is difficult to make the surface completely flat, and thus the metal roofing material will shrink.

2) The net pattern can reduce the glare in the sun.

3) If the checkered plate has slight scratches and small area indentations, it is not obvious.

4) Increase the strength of the steel plate.

5) It provides the architect with a choice. Patented patterns include cloth patterns (used in Ed Building in London), inlay patterns, pearl patterns and leather patterns. Wave and linear patterns can also be used. The patterned surface is particularly suitable for interior decoration, such as elevator panels, counters, wall panels and entrances. In external applications, consideration should be given to enabling stainless steel to clean the surface through rainwater and manual washing to avoid dead spots where dirt and airborne impurities are easy to gather, so as not to cause corrosion and affect the appearance.
8. Rough surface processing

The rough surface processing is one of the most commonly used surface processing. It is polished with a nylon abrasive belt or brush on the surface of the polished or bright annealed steel plate.