Stainless steel has the ability to resist atmospheric oxidation — that is, stainless steel, but also in the acid, alkali, salt medium is the ability to corrosion – that is, corrosion resistance. But its corrosion resistance is the size of its steel chemical composition, plus the state, the use of conditions and environmental media type and change.
Such as 304 stainless steel pipe fittings, in the dry and clean atmosphere, there is absolutely excellent resistance to corrosion, but it moved to the beach area, in a large amount of salt containing sea fog, will soon rust; and 316 steel performance good. Therefore, not any kind of stainless steel, in any environment can be resistant to corrosion, no rust.
Stainless steel is the surface of the formation of a thin layer of thin and strong and stable stable chromium oxide film (protective film), to prevent the continued infiltration of oxygen atoms, continue to oxidize, and the ability to obtain corrosion resistance. Once for some reason, the film has been constantly destroyed, the air or liquid oxygen atoms will continue to infiltrate or metal iron atoms continue to precipitate out to form loose iron oxide, metal surface will continue to rust.
But does not mean that no rust, stainless steel pipe fittings is not easy to rust and the composition of stainless steel has a great relationship. Stainless steel components in addition to iron, there are chromium, nickel, aluminum, silicon and so on. General stainless steel chromium content is generally not less than 12%, high or even up to 18%. Steel added chromium and other elements, you can change the performance of steel, such as steel, such as the molecular structure is more uniform in the steel surface is more likely to generate a layer of dense oxide protective film, etc., thereby greatly improving the ability of stainless steel corrosion resistance. So stainless steel can resist fire, water, acid, alkali and a variety of solutions to its corrosion, no rust. Scientists have found that the more uniform the internal structure of steel, the more closely connected components, the more difficult the corrosive invasion, coupled with the surface and attached a layer of oxide protective film, like steel to wear armor, natural It is not easy to rust.
The optimum temperature for stainless steel pipe fittings is 1050-1080 ° C.
The temperature quickly rose to this degree, according to the thickness of stainless steel pipe fittings to stay 1-3 minutes, and then quickly cooled to 100 ℃ below, remember to be rapid cooling, because 500-800 degrees Celsius are stainless steel sensitization temperature, stay in this range Too long will affect the molecular structure of stainless steel, leading to material changes.
Source: China Pipe Fittings Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)