Improvement measures for the surface pit defect of DIN 17100 St52-3 grade steel mild plate

The basic phases of DIN 17100 St52-3 grade steel mild plate, structural steel in the annealed state are ferrite and carbide. The alloy elements are dissolved in ferrite to form alloy ferrite, which depends on solid solution strengthening to increase strength and hardness, but at the same time reduce plasticity and toughness. The addition of alloying elements reduces the carbon content of the eutectoid point, which increases the proportion of pearlite in the structure and reduces the distance of the pearlite layer. This also increases the strength of the steel and reduces the plasticity.

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The main applications of normalizing are as follows:① For low carbon steel, DIN 17100 St52-3 grade steel mild plate. The hardness of low carbon steel after normalizing is slightly higher than that after annealing, and the toughness is also better, so normalizing can be used as the pretreatment of cutting.② For medium carbon steel, normalizing can be used as the final heat treatment instead of quenching and tempering treatment, or as the preparation treatment before surface quenching by induction heating.③ Normalizing can be used in tool steel, bearing steel, carburizing steel and so on, which can eliminate or inhibit the formation of network carbide, thus obtaining the good microstructure needed for spheroidizing annealing.④ Normalizing can refine the cast structure and improve the machinability of steel castings.

We have 4 typical production lines, which can produce hot rolled Seamless, LSAW, ERW and SSAW pipes. SSAW pipe production line range is OD 219.1mm-3500mm, wall thickness 3.2mm-25.4mm. Product DIN 17100 St52-3 grade steel mild plate annual capacity is 200 thousand tons.