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The corrosion of metal magnetic pump materials caused by the conveyed medium includes the following eight types: electrochemical corrosion, uniform corrosion, intergranular corrosion, pitting corrosion, crevice corrosion, stress corrosion, wear corrosion, and cavitation corrosion. (1) Electrochemical corrosion Electrochemical corrosion refers to the electrochemical process in which, due to differences in the electrode potentials of metals, a battery is formed at the contact surface between different metals, resulting in the corrosion of the anodic metal. Measures to prevent electrochemical corrosion: First, it is advisable to use the same metal material for the flow channels of the pump ； Secondly, measures such as using a sacrificial anode to protect the cathodic metal are employed. (2) Uniform corrosion Uniform corrosion refers to the uniform chemical corrosion of the entire metal surface when a corrosive liquid comes into contact with it. This is the most common form of corrosion, and it is also the least harmful type. Measures to prevent uniform corrosion include using appropriate materials (including non-metals) and considering sufficient corrosion allowance during pump design. (3) Intergranular corrosion Intergranular corrosion is a type of localized corrosion, primarily referring to the precipitation of chromium carbide between the grains of stainless steel. Intergranular corrosion has a significant corrosive effect on stainless steel materials. Materials subjected to intergranular corrosion lose almost all of their strength and ductility. Measures to prevent intergranular corrosion are: annealing the stainless steel, or using ultra-low carbon stainless steel (C＜0.03%). (4) Pitting corrosion Pitting corrosion is a type of local corrosion. Pitting corrosion is a phenomenon in which the rapid formation of hemispherical pits in a specific area on the metal surface occurs due to the local breakdown of the metal’s passive film. Pitting corrosion is mainly caused by CL￣. To prevent pitting corrosion, Mo-containing steels (typically 2.5% Mo) can be used, and the Mo content should also be increased as the CL￣ content and temperature rise. (5) Crevice corrosion Crevice corrosion is a type of local corrosion that occurs when a crevice is filled with a corrosive liquid; the decrease in oxygen content and/or the drop in pH within the crevice lead to the localized breakdown of the metal’s passivation film, thereby causing corrosion. Stainless steel often suffers from crevice corrosion in CL￣ solutions. Crevice corrosion and pitting corrosion have similar formation mechanisms. Both are caused by the action of CL￣ and the local destruction of the passivation film. As the CL￣ content increases and the temperature rises, the likelihood of crevice corrosion increases. The use of metals with high Cr and Mo contents can prevent or reduce the occurrence of crevice corrosion. (6) Stress corrosion: Stress corrosion refers to a type of localized corrosion that results from the combined effect of stress and a corrosive environment. Austenitic Cr–Ni steels are prone to stress corrosion in CL￣ media. As the CL￣ content, temperature, and stress increase, stress corrosion is more likely to occur. Generally, stress corrosion does not occur below 70–80°C. The measure to prevent stress corrosion is to use austenitic Cr–Ni steel with a high Ni content (25%~30% Ni). (7) Wear corrosion Wear corrosion refers to a type of erosive corrosion caused by high-speed fluids acting on metal surfaces. Fluid erosion wear corrosion is different from abrasion caused by solid particles present in the medium. Different materials also have varying resistance to wear and corrosion. The wear and corrosion resistance, from worst to best, is: ferritic Cr steel < austenite-ferritic steel < austenitic steel. (8) Cavitation corrosion: The corrosion that occurs in magnetic pumps due to cavitation is known as cavitation corrosion. The most practical and simple way to prevent cavitation corrosion is to prevent cavitation from occurring. For pumps that frequently experience cavitation during operation, to prevent cavitation corrosion, cavitation-resistant materials such as cemented carbide, phosphor bronze, austenitic stainless steel, and 12% chromium steel can be used.