Home > News > Industry News > Why does stainless steel pipe rust?

Why does stainless steel pipe rust?

Source:Jiangsu hengshuntai steel Co.,Ltd    Time:29 March 2021

  Stainless steel pipe, as the name implies, refers to steel that is resistant to weak corrosive media such as air, steam, and water, and chemically corrosive media such as acid, alkali, and salt, also known as stainless acid-resistant steel. However, in practical applications, some stainless steels have rusted unexpectedly.

  Stainless steel pipes appear rusty, which may have the following reasons:

  First, the generated intergranular erosion. This material without titanium and niobium has a tendency of intergranular corrosion. Adding titanium and niobium, together with unchanging treatment, can reduce intergranular corrosion. A high-alloy steel that can resist corrosion in the air or in a chemically corrosive medium. Stainless steel has a beautiful appearance and good corrosion resistance. It is not necessary to deal with the general conditions such as plating, but to demonstrate the inherent general performance of stainless steel. , A kind of steel used in many aspects, usually called stainless steel. High-alloy steels such as 13 chromium steel and 18-8 chromium-nickel steel represent functions. Analyzed from the perspective of metallography, because stainless steel contains chromium, a thin chromium film is formed on the surface. This film is separated from the oxygen intruding into the steel for corrosion resistance. In order to maintain the inherent corrosion resistance of stainless steel, steel must contain more than 12% chromium. Used in places where welding is required. The lower carbon content reduces the precipitation of carbides in the heat-affected zone close to the weld to a minimum, and the precipitation of carbides may cause intergranular corrosion and welding corrosion of stainless steel in some cases.

  Second, there is no solution treatment. The alloying elements are not dissolved into the matrix, resulting in low alloy content of the matrix structure and poor corrosion resistance.

  Third, there are chloride ions in the utilization situation. Chloride ions are ubiquitous, like salt/sweat traces/sea water/sea breeze/soil and so on. Stainless steel erodes very quickly in the presence of chloride ions, even surpassing popular low-carbon steel. Therefore, there are requirements for the utilization of stainless steel, and it needs to be wiped frequently to remove dust and keep it clean and dry. (So you can give him an "inappropriate utilization".) There is an example in the United States: a company used an oak container to contain a solution containing chloride ions. The container has been used for nearly a hundred years. It was planned to be replaced, because the oak material was not up to the modern age, the container leaked due to corrosion 16 days after the replacement of stainless steel.

Back to list

Related News