How to choose stainless steel and its corrosion resistance

The requirement for the use of most steel pipes is to maintain the original appearance of the building for a long time. When determining the type of stainless steel to be selected, the main considerations are the required aesthetic standards, the corrosiveness of the local atmosphere, and the cleaning system to be adopted.
The requirement for the use of most steel pipes is to maintain the original appearance of the building for a long time. When determining the type of stainless steel to be selected, the main considerations are the required aesthetic standards, the corrosiveness of the local atmosphere, and the cleaning system to be adopted. Increasingly, however, other applications simply seek structural integrity or impermeability. For example, roofs and side walls of industrial buildings. In these applications, the owner's cost of construction may be more important than aesthetics, and the surface is not very clean. The effect of using 304 stainless steel in a dry indoor environment is quite good. However, to maintain its appearance outdoors in both the country and the city, frequent washing is required. In heavily polluted industrial areas and coastal areas, the surface will be very dirty and even rusted. However, to obtain the aesthetic effect in the outdoor environment, nickel-containing stainless steel is required. Therefore, 304 stainless steel is widely used in curtain walls, side walls, roofs and other construction purposes, but in severely corrosive industries or marine atmospheres, it is best to use 316 stainless steel. The advantages of using stainless steel in structural applications are now fully realized. There are several design criteria that include 304 and 316 stainless steel. Because "duplex" stainless steel 2205 has integrated good atmospheric corrosion resistance with high tensile strength and elastic limit strength, this steel is also included in the European standards. Product Shapes In fact, stainless steel is manufactured in a full range of standard metal shapes and sizes, and there are many special shapes. The most commonly used products are made of sheet and strip steel, and special products are also produced from medium and thick plates, for example, the production of hot-rolled structural steel and extruded structural steel. There are also round, oval, square, rectangular and hexagonal welded or seamless steel pipes and other forms of products, including profiles, bars, wires and castings.
Product Shapes In fact, stainless steel is manufactured in a full range of standard metal shapes and sizes, and there are many special shapes. The most commonly used products are made of sheet and strip steel, and special products are also produced from medium and thick plates, for example, the production of hot-rolled structural steel and extruded structural steel. There are also round, oval, square, rectangular and hexagonal welded or seamless steel pipes and other forms of products, including profiles, bars, wires and castings. When the amount of chromium added reaches 10.5%, the atmospheric corrosion resistance of steel increases significantly, but when the chromium content is higher, although the corrosion resistance can still be improved, it is not obvious. The reason is that alloying steel with chromium changes the type of surface oxide to a surface oxide similar to that formed on pure chromium metal. This tightly adhered chromium-rich oxide protects the surface from further oxidation. This kind of oxide layer is extremely thin, and the natural luster of the steel surface can be seen through it, making the stainless steel have a unique surface. Moreover, if the surface is damaged, the exposed steel surface will react with the atmosphere to repair itself, re-form this "passive film" and continue to play a protective role. Therefore, all stainless steels have a common characteristic, that is, the chromium content is above 10.5%.