A variety of surface processing of stainless steel has widened its application field. Different surface processing makes the surface of stainless steel different, so that it is unique in its application. In the field of building applications, there are many reasons for the importance of surface processing of stainless steel.
One, the basic types of surface processing
There are basically five kinds of surface processes that can be used for stainless steel. They can be combined and used to transform more and more final products.
The five species are:
- Rolling surface processing
- Mechanical surface processing
- Chemical surface processing
- Reticulated surface processing
- Color surface processing
There are some special surface treatments, but no matter which surface is specified, the following steps should be followed:
1, with manufacturers to agree on the necessary surface processing, it is best to prepare a sample for future volume production standards.
2. When large areas are used, such as composite boards, the same base must be used to ensure that the base rolls or rolls are used in the same batch.
3, the manufacturing process should be taken into consideration when selecting surface processing. For example, in order to remove the bead, it is possible to repair the weld and restore the original surface processing. The pattern board is hard to even meet this requirement.
4, for some surface processing, grinding or polishing texture is directional, is called unidirectional. If it is used vertically and not horizontally, dirt is not easily attached to it, and it is easy to clean.
Two. Rolling surface processing
There are three basic rolling surface processes for sheet and strip, which are represented by plate and village production processes.
No.1: hot rolling, annealing, pickling and descaling. The surface of the treated steel sheet is a dull surface and a bit rough.
No.2D: the surface is better than N0.1, and it is also a bleak surface. After cold rolling, annealing, descaling, and finally rolling with the wool surface roller.
No.2B: This is the most commonly used in architectural applications. Except for the last mild cold rolling of the polishing roll after the annealing and the descaling, the other processes are the same as the 2D, and the surface is slightly light and can be polished.
No.2B bright annealing: This is a reflective surface that is rolled through a polishing roller and annealed in a controlled atmosphere. Bright annealing still keeps its reflective surface and does not produce oxide scales. Because no oxidation reaction occurs in the process of bright annealing, no pickling and passivation treatment is necessary.
Three, polishing surface processing
No.3: expressed by 3A and 3B. 3A: the surface is evenly grind and the abrasive particle size is 80~100. 3B: the wool surface is polished with uniform straight lines on the surface. It is usually made by grinding and polishing the abrasive belt with a size of 180~200 on the 2A or 2B board.
No.4: unidirectional surface processing, not strong reflectivity, this surface processing may be the most widely used in building applications. The process is first polished with coarse abrasives, and then grinded with a particle size of 180.
No.6: it is a further improvement to No.4, which is to polish the No.4 surface with tampo brush in abrasive and oil medium. There is no surface processing in British standard 1449, but it can be found in the US standard.
No.7: known as bright polishing, it is polishing the surface that has been finely worn but still worn. 2A or 2B boards are usually used, with fiber or cloth polishing wheels and corresponding polishing paste.
No.8: mirror polished surface, high reflectivity, usually referred to as mirror surface processing, because it reflects the image very clear. The stainless steel is continuously polished with fine abrasives and then polished with very fine polishing paste. What should be noted in building applications is that such a surface will leave a fingerprint if it is used in areas where the flow of personnel is large or where people often touch. The handprints can be erased, but sometimes they are beautiful.
Four, surface roughness
The classification of rolling surface finishing and polishing surface machining is a description of the extent to which it can be achieved. Another effective method is to measure surface roughness. The standard method of measurement is called CLA (mean value of the center line). The measuring instrument moves horizontally on the surface of the steel plate to record the change range of the peak valley. The smaller the CLA’s number, the smoothed the surface. The final results of different grades can be seen from the surface processing and CLA numbering in the following table.
Five. Mechanical polishing
Note: we should remember that grinding with sandpaper or sand belt in grinding operation is basically a polishing operation, leaving a fine line on the surface of the steel plate. We have encountered trouble when using alumina as abrasive, partly due to pressure. Any abrasive parts of the equipment, such as abrasive belts and grinding wheels, must not be used before other stainless steel materials. Because this will pollute the surface of the stainless steel.
Six. Electrolytic polishing
This is a metal removal process. In this process, stainless steel is used as the anode in the electrolyte, and the metal is removed from the surface after electrified. The process is usually used for parts processing because their shape is difficult to be polished by 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 cause more obvious impurities on the surface, especially titanium and niobium stabilized materials will cause differences in the weld area due to granular impurities.
Small welding scar and sharp edge can be removed by this process. The process focuses on the surface protrusions, giving priority to dissolving them. The electrolytic polishing process is to immerse stainless steel in heated liquid, and the ratio of liquid involves many proprietary technology and patented technology. The effect of electrolytic polishing of austenitic stainless steel is very good.
Seven. Reticulated surface processing
There are many kinds of patterns that can be used in stainless steel. The advantages of making steel plates with textured or textured surfaces are as follows:
1) reduce “oil can-ning”, a term used to describe the surface of a bright material, which looks inhomogeneous from an optical angle. For example, a large area of decorative panels, even after stretching straightening or tension leveling, is difficult to make the surface completely flat, resulting in metal roof material shrinkage.
2) netted patterns can reduce glare in the sun.
3) if the pattern board has slight scratches and small area indentation, it is not very obvious.
4) increase the strength of the steel plate.
5) the choice is provided for the architect. Patented designs include cloth patterns (used for Ed building in London), mosaic designs, pearls and leather stripes. Ripple and linear patterns can also be used. The pattern surface is especially suitable for interior decoration, such as elevator panels, counters, panels and entrance. The external application should be taken into consideration to make the stainless steel clean the surface through rain and artificial scour, and avoid the dead angle which is easy to gather dirt and air impurities, so as to avoid the beauty of corrosion.
Eight. Surface processing of wool surface
Surface finishing is one of the most commonly used surface processes. It is polished or annealed on the surface of steel plate with nylon abrasive belt or brush.
Source: China Alloy Steel Pipes Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)