As a Railway Fastening System Exporter, let me share with you.
We all know that in order to prevent the problem of corrosion, the fasteners on the track and railway will be connected and installed with stainless steel, but these fasteners are in the assembly stage as the fasteners damage the coating during the fastening process. This leads to corrosion of the fasteners. Therefore, it is also very important to remove rust and prevent rust from fasteners on railways. The following China Standard Parts Network, based on the understanding of the fastener corrosion problem, shares in detail how to protect the railway vehicle fastener corrosion problem.
Railway Fastening System
Listed below are pictures of rusty rail vehicle fasteners:
1. Analysis of the causes of fastener corrosion
High-resistant fasteners are a kind of metal, and its corrosion principle is almost the same as that of other metal materials. In most cases, the corrosion of metal materials is the result of electrochemical reactions, but in some cases it is only the result of pure chemical reactions or physical changes of metals, and these two situations also affect the corrosion of metal materials. Not uncommon. The other is to destroy the plating material during the fastening process of the fastener.
The corrosion phenomenon and mechanism related to the stainless steel body of railway vehicles are discussed below.
Pitting corrosion is also called pit corrosion or pinhole corrosion. Due to the inhomogeneity of defects, impurities and solutes in metal materials, when the medium contains certain active anions (such as CI), these active anions are first adsorbed on certain points on the metal surface, thereby making the metal surface The self-passivation film is destroyed. Once this layer of self-passivation film is damaged and lacks the ability of self-passivation repair, the metal surface will corrode. When rail vehicles are parked in a harbor or transported by sea, they will inevitably come into contact with sea water or salt spray formed by sea water. After being parked at the seaside, salt particles will form on the side walls and rust; when the vehicle is in contact with acid rain, Break under high heat and humidity conditions
The self-passivation film is broken, so that the surface of the fastener is relatively uniformly rusty.
Once pitting corrosion occurs, if it cannot be removed in time, the newly exposed body metal is in an activated state, and part of the passivation film is still in a passive state, thus forming an active-passive corrosion battery. Because the area of the rusted anode is much smaller than the area of the cathode, the anode current density is very large, so the corrosion develops deep, and the metal surface will be corroded into deep holes. The degree of pitting corrosion varies greatly. Generally, the depth of severe pitting corrosion is much larger than its diameter.
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