Basic Types of Stainless Steel Surface Processing
Feb 27, 2019

The various surface processing of stainless steel widens its application field. Different surface processing makes the surface of stainless steel different and makes it unique in application. In the field of construction application, there are many reasons why surface processing of stainless steel is important.

I. Basic Types of Surface Processing

There are roughly five kinds of surface processing that can be used for stainless steel. They can be combined to produce more final products.

There are five categories:

1. Rolling Surface Processing

2. Mechanical Surface Processing

3. Chemical Surface Processing

4. Machining of reticulated surface and color surface

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

1. To negotiate with the manufacturer the required surface processing, it is better to prepare a sample as the standard for future batch production.

2. When using in large area, such as composite board, it is necessary to ensure that the same batch of base coil or coil is used.

3. When choosing the surface processing, we should consider the manufacturing process. For example, in order to remove the beads, we may need to grind the weld and restore the original surface processing. It is difficult or even impossible to meet this requirement.

4. For some surface processing, grinding or polishing lines are directional, known as unidirectional. If the lines are vertical rather than horizontal when used, the dirt is not easy to adhere to and easy to clean.

2. Rolling Surface Processing

There are three basic rolling surface processes for sheet and strip, which are expressed by the production process of sheet and strip village.

No.1: After hot rolling, annealing, pickling and descaling. The surface of treated steel plate is a kind of dim surface, a little rough.

No.2D: It's better than N0.1, and it's also a dim surface. After cold rolling, annealing, descaling, and finally light rolling with surface rolls.

No.2B: This is the most commonly used in architectural applications. Except for the last slight cold rolling with polishing rolls after annealing and scaling, the other processes are the same as 2D. The surface is slightly luminous and can be polished.

No.2B Bright Annealing: This is a reflective surface, which is rolled by polishing rolls and annealed in a controlled atmosphere. Bright annealing still maintains its reflective surface and does not produce oxide scale. Because there is no oxidation reaction during bright annealing, no acid pickling and passivation treatment are needed.

3. Polishing Surface Processing

No.3: Expressed by 3A and 3B. 3A: The surface is ground evenly, and the abrasive particle size is 80-100. 3B: The surface is polished with uniform straight lines. It is usually polished once on 2A or 2B plate with abrasive belt of 180-200 particle size.

No.4: One-way surface processing, which is not reflective, may be the most widely used in construction applications. The process steps are polishing with coarse abrasives first, and then grinding with 180-size abrasives.

No.6: It is a further improvement of No.4. It polishes No.4 surface with Tampico polishing brush in abrasive and oil medium. There is no surface finish in British Standard 1449, but it can be found in American Standard.

No.7: It's called bright polishing. It's polishing a surface that has been polished very fine but still has a wear mark. Usually 2A or 2B boards are used with fibre or cloth polishing wheels and corresponding polishing paste.

No.8: Mirror polished surfaces, with high reflectivity, are often referred to as mirror polishing because they reflect very clear images. The stainless steel is polished continuously with fine abrasives and then polished with very fine polishing paste. In building applications, it should be noted that if the surface is used in places where the flow of people is large or people often touch it, it will leave handprints. Handprints can be erased, of course, but sometimes they affect beauty.

4. Surface Roughness

The classification of rolling and polishing surface processing is to show the extent to which it can be achieved. Another effective representation is the measurement of surface roughness. The standard measurement method is called CLA (center line average). The instrument moves horizontally on the surface of the steel plate and records the variation of peak and valley. The smaller the number of CLA, the smoother the surface. The final results of different grades can be seen from the surface processing and CLA numbers in the table below.

5. Mechanical Polishing

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

6. Electropolishing

This is a metal removal process in which stainless steel acts as an anode in the electrolyte and the metal is removed from the surface after electrification. This process is usually used to process parts because their shapes are difficult to be polished by traditional methods. The process is often used on the surface of cold-rolled steel sheets, because the surface of cold-rolled steel sheets is smoother than that of hot-rolled steel sheets. However, electropolishing can make the surface impurities more obvious, especially for the materials stabilized by titanium and niobium, because of the granular impurities, the weld zone will be different.

Small weld scars and sharp edges can be removed by this process. The process focuses on the treatment of prominent parts on the surface, giving priority to their dissolution. Electrolytic polishing process is to immerse stainless steel in heated liquid. The proportion of liquid involves many proprietary and patented technologies. The electropolishing effect of austenitic stainless steel is very good.

7. Surface Processing of Mesh

There are many kinds of patterns that stainless steel can adopt. Addition of steel plate

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