Stainless steel polishing for surface processing
The surface processing of stainless steel is different, so that it has a variety of surface processing applications. In the field of architectural application, the surface processing of stainless steel is important for many reasons.
Basic types of surface processing
There are about five kinds of surface processing that can be used for stainless steel. They can be combined to produce more final products.
The five species are:
- Rolling surface processing
- Mechanical surface processing
- Chemical surface processing
- Chequer surface processing
- Color surface processing
There are also some special surface finishes, but no matter which one is specified, the following steps should be followed:
- 1. Work with the manufacturer to determine the required surface finish. It is best to prepare a sample as the standard for future batch production.
- 2. When using in large area (such as composite board, it must be ensured that the same batch of base plate or coil material is used.)
- 3. The selection of surface processing should take into account the manufacturing process, for example, in order to remove weld beads, the weld may have to be ground and the original surface finish must be restored. It is difficult or even impossible to meet this requirement.
- 4. For some surface processing, grinding or polishing of the grain is directional, known as unidirectional. If the lines are vertical rather than horizontal, the dirt is not easy to adhere to and easy to clean.
Rolling surface processing
There are three basic rolling surface treatments for plate and strip, which are represented by the production process of steel plate and strip.
- No.1: After hot rolling, annealing, pickling and descaling. The surface of treated steel plate is a kind of dull surface, a little rough.
- No.2D: Better than N0.1 surface processing, but also dark surface. After cold rolling, annealing, descaling, and finally light rolling with rough surface roller.
- No.2b: This is the most commonly used construction application. Except for the last light cold rolling with polishing roller after annealing and descaling, other processes are the same as 2D, and the surface is slightly luminous and can be polished.
- No.2b bright annealing: This is a reflective surface that is rolled by a polishing roller and finally annealed in a controlled atmosphere. After bright annealing, the reflective surface is kept and no oxide scale is produced. Since there is no oxidation reaction in the process of bright annealing, pickling and passivation are not needed.
Polishing surface processing
- No.3: Represented by 3a and 3b. 3A: the surface is evenly ground and the abrasive particle size is 80-100. 3b: the rough surface is polished, and the surface has uniform straight lines. It is usually made by polishing and grinding the abrasive belt with particle size of 180-200 on 2A or 2B plate at one time.
- NO.4: Unidirectional surface processing, with poor reflection, may be the most widely used in architectural applications. The process step is to polish with coarse abrasive at first, and then to grind with abrasive with particle size of 180.
- No.6: It is a further improvement on No.4, which is to polish the surface of No.4 with Tampico polishing brush in abrasive and oil medium. This finish is not available in BS 1449, but can be found in US standards.
- No.7: It is called bright polishing, which is used to polish the surface that has been ground very fine but still has grinding marks. Generally, 2A or 2B plates are used, and the polishing wheel and corresponding polishing paste are polished with fiber or cloth.
- No.8: Mirror polished surface, with high reflectivity, is usually called mirror surface processing because it reflects a clear image. The stainless steel is continuously polished with fine abrasive and then polished with very fine polishing paste. In architectural applications, it should be noted that if the surface is used in places with large flow of people or people often touch it, fingerprints will be left. Of course, fingerprints can be erased, but sometimes they affect the appearance.
The classification of rolling surface machining and polishing surface processing is to indicate the degree that can be achieved. Another effective representation method is to measure the surface roughness. The standard measurement method is called cla (center line average), and the meter moves horizontally on the surface of the steel plate to record the changes of peak and valley. The smaller the cla number, the smoother the surface.
Note: we should remember that grinding with sandpaper or abrasive belt in grinding operation is basically a polishing and cutting operation, leaving fine lines on the surface of steel plate. We have had trouble using alumina as an abrasive, in part because of pressure problems. Any grinding parts of the equipment, such as abrasive belt and grinding wheel, must not be used for other non stainless steel materials before use. Because this will contaminate the stainless steel surface.
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 layer after being electrified. This process is usually used to process parts because their shape is difficult to polish 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 plate. However, electropolishing can make the surface impurities more obvious, especially for titanium and niobium stabilized materials, there will be differences in the weld area due to the granular impurities.
Small welding scars and sharp edges can be removed by this process. This process focuses on the treatment of protrusions on the surface, preferentially dissolving them. Electrolytic polishing process is to soak stainless steel in heated liquid. The ratio of liquid involves many proprietary and patented technologies. The electropolishing effect of austenitic stainless steel is very good.
Chequer surface processing
There are many kinds of patterns for stainless steel. The advantages of adding pattern or reticulated surface processing to the steel plate are as follows:
- 1) Reduce “oil can Ning,” a term used to describe a bright material surface that is optically uneven. For example, it is difficult to make the surface of large-area decorative panel completely flat even after tension straightening or tension straightening, so the metal roof material will shrink.
- 2) The checkered pattern reduces glare in the sun.
- 3) If there are slight scratches and small area indentation on the checkered plate, they are not obvious.
- 4) Increase the strength of the steel plate.
- 5) It provides a choice for architects.
The patented designs include cloth patterns (for ED house in London), inlays, pearls and leather patterns. Ripple and linear patterns can also be used. Patterned surfaces are particularly suitable for interior finishes such as elevator panels, counters, siding and entrances. In external application, it should be considered that the stainless steel surface can be washed by rainwater and manual washing, so as to avoid the dead corner which is easy to gather dirt and air impurities, so as to avoid corrosion and affect the appearance.
Rough surface processing
Rough surface machining is one of the most commonly used surface processing. It is used to polish the steel plate surface after polishing or bright annealing with nylon abrasive belt or brush.
Source: China Stainless steel Plate Manufcturer – Yaang Pipe Industry (www.steeljrv.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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