Reasons for pitting corrosion of 201 stainless steel plate

Discussion on the causes of pitting corrosion of 201 stainless steel pipes The general situation of 201 stainless steel pipes has high corrosion resistance due to the formation of dense chromium oxide films. However, local point erosion is unavoidable. Pitting corrosion is extremely hidden and sudden, especially in the fields of petroleum, chemical industry, nuclear power, etc., pitting corrosion can easily cause perforation of the pipe wall, cause a large amount of oil and gas leakage, and even cause disasters such as fire and explosion. . Since the 1930s up to now, human beings have been exploring the pitting corrosion nucleation mechanism of stainless steel without interruption. But the initial location of pitting is always considered "random and not predictable". The research of Ma Xiuliang and other scientists showed that the local ablation of manganese sulfide originates from the interface between it and the "tumor" under the premise of a certain medium, and then slowly expands into the material body. The study also shows that the oxide nano-octahedron makes the local ablation of manganese sulfide different in speed. On this basis, the research team, in cooperation with Professor Hu Peijun from Queen's University Belfast, UK, determined that oxide nano-octahedrons with strong activity and easy to rapidly dissolve manganese sulfide around them have metal ions as their The characteristics of the outer surface are similar to "malignant tumor"; on the contrary, the less active nano-octahedron uses oxygen ions as its outer surface, which is similar to "benign tumor". This discovery provides direct evidence for revealing the starting position of manganese sulfide ablation in the early stage of stainless steel pitting, and promotes people's familiarity with the pitting corrosion mechanism of 201 stainless steel from the previous micron standard to the atomic standard.