Stainless steel pipes are commonly used materials in the industry. Generally, stainless steel is not easy to rust, but it may also cause rust on stainless steel pipes due to environmental factors. When we find rust on stainless steel, we need to How to deal with ****, the following two **** methods provided by China Standard Parts Network for us to deal with.

1. It is chemical corrosion: surface pollution: oil, dust, acid, alkali, salt, etc. attached to the surface of the workpiece are converted into corrosive media under certain conditions, and chemically react with some components in the stainless steel parts, resulting in chemical corrosion and rust . Surface scratches: The damage to the passivation film by various scratches reduces the protective ability of stainless steel, and it is easy to react with chemical media, resulting in chemical corrosion and rust. Cleaning: After pickling and passivation, cleaning is not clean, resulting in residual liquid remaining, which directly corrodes stainless steel parts.

2. It is electrochemical corrosion: carbon steel pollution: scratches caused by contact with carbon steel parts and corrosive media form a primary battery to produce electrochemical corrosion. Cutting: The adhesion of rust-prone substances such as cutting slag and splashing and the corrosive medium form a primary battery to produce electrochemical corrosion. Baking school: The composition and metallographic structure of the flame heating area change unevenly, and form a galvanic cell with the corrosive medium to produce electrochemical corrosion. Welding: The physical defects and chemical defects in the welding area and the corrosive medium form a galvanic cell to produce electrochemical corrosion. Material: The chemical defects and surface physical defects of stainless steel are conducive to the formation of galvanic cells with corrosive media to produce electrochemical corrosion. Passivation: The passivation effect of pickling is not good, resulting in uneven or thin passive film on the surface of stainless steel, which is easy to form electrochemical corrosion. Cleaning: The remaining pickling passivation residue and stainless.

Stainless steel pickling passivation solution

1. Features

      1. In this way, the problem of environmental pollution caused by the formation of nitrogen oxides in the pickling process can be completely eradicated, investment is saved, and the production environment is improved.

      2. The pickling solution can effectively remove the oxide scale, but the corrosion effect on the stainless steel itself is far weaker than that of the traditional pickling solution, thereby reducing the metal loss caused by the pickling.

      3. The quality of the product is no less than that of the traditional craft and the production cost is similar to that of the traditional craft.

      4. The process has strong adaptability. It is suitable for pickling of various austenitic stainless steels and pickling of various types of ferritic stainless steels. In terms of pickling products, it is not only suitable for pickling of various stainless steel strips, bars and wires of metallurgical enterprises, but also suitable for pickling of various stainless steel castings and forgings.

2. Process

1. Degreasing

The pickling solution is difficult to remove grease, and the presence of a small amount of grease on the metal surface can greatly reduce the pickling speed. Metallurgical enterprises should carry out pickling immediately after heat treatment, so it is not necessary to carry out degreasing treatment before pickling. However, in the machinery industry, the metal surface is likely to be stained with grease, and it is necessary to remove oil before pickling.

2. Loosening treatment

Not all heat-treated stainless steels can be pickled directly. After heat treatment of ferritic and martensitic stainless steel, a dense and tenacious oxide scale is formed on the surface, which is difficult to be removed by direct pickling. The hot-rolled austenitic stainless steel plate is annealed in a gas furnace to form a thick Fe3O4 that is insoluble in acid, which is also difficult to be removed by direct pickling. The above stainless steel materials must be subjected to various loosening treatments before pickling and passivation treatment.

Three, stainless steel and other surface treatment wastewater treatment:

Duplex stainless steel and other surface treatment wastewater treatment: after cleaning the stainless steel surface, the discharged acid aqueous solution, in order to ask the user to collect the wastewater in a pool, and then neutralize it with lime, sodium carbonate (soda), sodium hydroxide, etc. Discharge when the pH value is 7-8.