The term “stainless steel” not only refers to one kind of stainless steel, but also refers to more than one hundred kinds of industrial stainless steel, so each kind of stainless steel developed has good performance in its specific application field. The key to success is first to understand the purpose, and then to determine the right steel grade.
There are usually only six kinds of steel related to the application field of building construction. They all contain 17% ~ 22% chromium, and the better steel also contains nickel. The addition of molybdenum can further improve the atmospheric corrosiveness, especially the resistance to chloride atmosphere.
The degree of atmospheric corrosion varies from region to region. For the convenience of explanation, the region is divided into four categories: rural, urban, industrial and coastal areas.
Villages are basically pollution-free areas. The population density of the region is low, with only pollution-free industries.
The city is a typical residential, commercial and light industry area with light pollution, such as traffic pollution.
Industrial area is the area of air pollution caused by heavy industry. Pollution may be caused by gases formed by fuel oil, such as oxides of sulfur and nitrogen, or other gases released by chemical plants or processing plants. Suspended particles in the air, such as dust or iron oxide deposits from steel production, can also increase corrosion.
Coastal areas usually refer to areas within a mile of the sea. However, the ocean atmosphere can spread deep inland, especially on the island. The prevailing wind comes from the ocean and the climate is bad. If there is industrial pollution, it will be more corrosive.
In the selection, it is important to determine whether there are local factors that affect the site environment. For example, if stainless steel is used under the factory chimney, near the air conditioning exhaust damper or scrap yard, there will be unusual conditions.