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Treatment technology of alloy seamless pipe

Alloy seamless pipe is a pearlite heat-resistant alloy structural steel, which has good high-temperature mechanical properties, high plasticity during cold deformation, no tempering brittleness tendency, good machinability and acceptable weldability. It is generally used under high-temperature normalizing and high-temperature tempering; It is mainly used for superheater tubes with working temperature of 570 ~ 585 ℃ in pressure boiler, pipeline accessories with medium temperature ≤ 570 ℃ (flange, flange cover, etc.), and forgings for other purposes (such as flat hole cover and thermometer socket).

Before making coating (oil or copper plating, etc.) on the surface of alloy steel pipe, it is necessary to remove the oxide scale and defect layer on the surface, avoid stress concentration and reduce its service strength. At present, the commonly used treatment methods include cleaning, tool derusting, acid pickling and shot blasting, and shot blasting is an ideal treatment method for pipeline derusting.

The principle of shot blasting for alloy seamless pipe is to drive the blade to rotate at a high speed through a high-power motor, so that the abrasive such as steel sand, steel shot, iron wire section and minerals can be sprayed on the metal surface at a high speed. Under the action of impact and friction, the rust and other dirt on the metal surface will show the surface with roughness and reveal the true color of the metal. On the one hand, the treatment method solves rust, oxide and dirt; On the other hand, under the action of abrasive violent impact and friction, the steel pipe can reach the required surface roughness. However, this surface treatment method is easy to embed the abrasive used for shot blasting into the surface of the steel pipe to be processed, which accelerates the electrochemical corrosion of the steel pipe surface. It not only has high cost, but also has limited ability to improve the surface quality of the steel pipe. Therefore, there is an urgent need for a steel pipe surface treatment process before machining, which can not only obtain better surface processing quality, but also fully reduce or even cause the adverse factors of electrochemical corrosion on the steel pipe surface.

Practice has proved that the grinding process is a better solution than other mechanical cutting processes. Abrasive belt grinding is a kind of composite processing technology integrating grinding, grinding and polishing; It has the advantages of grinding workpiece surface, good quality, not easy to introduce pollutants and low processing cost. As a modern machining method as important as grinding wheel grinding, abrasive belt grinding technology is one of the means in steel pipe grinding technology.