The variety of surface processing of stainless steel broadens its application field, and different surface processing makes the surface of stainless steel different, so that it has its own place in application. In the field of construction applications, the surface processing of stainless steel is important for many reasons.
First, the basic types of surface processing
There are roughly five kinds of surface processing that can be used for stainless steel, which can be combined to transform more final products.
The five categories are:
1. Rolling surface processing
2. Mechanical surface processing
3. Chemical surface processing
4. Mesh surface processing and color surface processing
There are also some special surface finishes, but no matter which surface finish is specified, the following steps should be followed:
1, together with the manufacturer to agree on the required surface processing, it is best to prepare a sample, as the standard for future mass production.
2, when using a large area, such as composite plates, it must be ensured that the base plate or coil used is the same batch.
3, the selection of surface processing should take into account the production process, for example: in order to remove the bead, it may be necessary to repair the weld, but also to restore the original surface processing. Pattern plate is difficult or even impossible to meet this requirement.
4, for some surface processing, grinding or polishing lines are directional, known as one-way. If the grain is vertical rather than horizontal when used, the dirt is not easy to adhere to it, and it is easy to clean.
Second, rolling surface processing
There are three basic rolled surface finishes for sheets and strips, which are represented by the production process for sheets and strips.
No.1: After hot rolling, annealing, pickling and descaling. The surface of the treated steel plate is a dull surface, a little rough.
No.2D: Better than N0.1 surface processing, but also dim surface. After cold rolling, annealing, descaling, and finally light rolling with rough roller.
No.2B: This is most commonly used in construction applications, except for the last light cold rolling with a polishing roller 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 that is rolled by polishing rollers and subjected to final annealing in a controlled atmosphere. Bright annealing still maintains its reflective surface and does not produce oxide. Since no oxidation reaction occurs during the bright annealing process, pickling and passivation are not required.
Three, 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: Rough finish, the surface has a uniform straight grain, usually with a particle size of 180 ~ 200 sand belt on 2A or 2B plate polishing.
No.4: One-way surface processing, not very reflective, this surface processing may be the most widely used in construction applications. The process step is first polishing with coarse abrasive, and finally grinding with abrasive particle size of 180.
No.6: A further improvement on No.4 by polishing the surface of No.4 with a Tampico polishing brush in abrasive and oil media. This surface finish is not included in the British Standard 1449", but can be found in the US standard.
No.7: Known as bright polishing, is the polishing of the surface that has been ground very fine but still has wear marks. A 2A or 2B plate is usually used, with a fiber or cloth polishing wheel and the corresponding polishing paste.
No.8: Mirror polished surface, high reflectivity, often referred to as mirror surface processing, because it reflects the image is very clear. The stainless steel is continuously polished with a fine abrasive and then polished with a very fine polishing paste. In architectural applications, it should be noted that this surface will leave handprints if used in places with a large flow of people or where people often touch it. Handprints can be erased, of course, but sometimes they affect the appearance.
Fourth, surface roughness
The classification of rolled surface machining and polished surface machining is to indicate the degree that can be achieved, and another effective representation is to measure the surface roughness. The standard measurement method is called CLA (centerline mean), and the meter moves laterally over the surface of the steel plate to record the amplitude of the change in the peaks and valleys. The smaller the CLA number, the smoother the surface. The final results of different grades can be seen from the surface finish and CLA numbers in the table below.
Five, mechanical polishing
Note: We should remember that the grinding operation with sandpaper or sanding belt is basically a polishing cutting operation, leaving very fine lines on the surface of the steel plate. We have had problems with alumina as an abrasive, partly due to pressure issues. Any abrasive parts of the equipment, such as abrasive belts and grinding wheels, must not be used on other non-stainless steel materials before use. Because this will contaminate the stainless steel surface.
Six, electrolytic polishing
This is a metal cleaning process in which stainless steel acts as the anode in the electrolyte and the metal is removed from the surface layer after electricity is applied. The process is often used for the processing of parts because their shapes are difficult to polish with traditional methods. The process is often used on the surface of cold-rolled steel plates because the surface is smoother than the surface of hot-rolled steel plates. However, electrolytic polishing will make the surface impurities more obvious, especially titanium and niobium stabilized materials will make differences in the weld area due to granular impurities.
Small welding scars and sharp edges can be removed by this process. The process focuses on the protruding parts of the surface, and the priority is to dissolve them. The electrolytic polishing process is to soak stainless steel in heated liquid, and the ratio of liquid involves many proprietary and patented technologies. The electrolytic polishing effect of austenitic stainless steel is very good.
Seven, mesh surface processing
Stainless steel can be used in many types of patterns. The advantages of adding a pattern or mesh surface processing to the steel plate are as follows:
1) Reduce the "oil can-ning" of metal roofing materials, a term used to describe surfaces of shiny materials that are uneven from an optical point of view. For example: a large area of decorative board, even after stretching straightening or tension correction is difficult to make the surface completely straight, so there will be metal roofing material crumpling.
2) Mesh patterns can reduce glare in the sun.
3) If there are slight scratches and small area indentation on the pattern plate, it is not obvious.
4) Increase the strength of the steel plate.
5) Provide the architect with a choice. Patented patterns include cloth (for the Ed Building in London), mosaics, pearls, and leather. Corrugations and linear patterns can also be used. The patterned surface is particularly suitable for interior decoration, such as elevator panels, counters, siding and entrances. The external application should take into account that the stainless steel can be washed through the rain and artificial washing surface, to avoid the dead Angle that is easy to gather dirt and air impurities, so as not to cause corrosion affecting the appearance.
Eight, rough surface processing
Rough surface finishing is one of the most commonly used surface finishing, it is polished on the polished or bright-annealed steel plate surface with nylon grinding tape or brush.
