Stainless steel authenticity identification
There are many kinds of stainless steel, which can be divided into austenitic type and martensitic or ferritic type according to the organizational structure at room temperature. Austenitic forms are non-magnetic or weakly magnetic, and martensitic or ferritic forms are magnetic. However, this is not necessarily the case. For example, the Austenitic 304 material usually used as a decoration tube plate is generally non-magnetic, but magnetic properties may also appear due to chemical composition fluctuations or different processing states caused by smelting, which cannot be considered counterfeit or unqualified. In addition, 304 stainless steel after cold processing, the structure will also be transformed to martensitic, the greater the deformation of cold processing, the more martensitic transformation, the greater the magnetic steel. On the contrary, the quality of the second point of the 200 series stainless steel, it is likely to be without magnetic, thus determining that it is genuine stainless steel, it is a big mistake.
People often judge the quality of stainless steel by magnet adsorption. In fact, this is an unrealistic way to distinguish. Relying on the traditional method of determining whether there is magnetic stainless steel is likely to suffer losses. Stainless steel refers to: in the atmosphere and acid, alkali, salt and other corrosive media showing passivity, corrosion resistance without rust of high chromium (generally 12%~30%) alloy steel. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel. The basic alloy elements of stainless steel also include nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the requirements of various uses for the structure and performance of stainless steel. Stainless steel is easy to be corroded by chloride ions, because chromium, nickel and chlorine are isoelements, and isoelements will be exchanged and assimilated to form corrosion of stainless steel.
When determining the type of stainless steel to be selected, the main consideration is the required aesthetic standards, the corrosiveness of the local atmosphere and the cleaning system to be used. However, other applications are increasingly simply seeking structural integrity or impermeability. For example, the roofs and side walls of industrial buildings. In these applications, the owner's construction cost may be more important than aesthetics, and the surface is not very clean. 304 stainless steel works quite well in dry indoor environments. However, in rural and urban areas, if you want to maintain its appearance outdoors, it needs to be cleaned frequently. In heavily polluted industrial areas and coastal areas, the surface will be very dirty and even rust. However, to obtain the aesthetic effect in the outdoor environment, it is necessary to use nickel-containing stainless steel.
