What are the characteristics of weld impact toughness of high frequency steel pipe

The welding process of high frequency steel pipe is to use the skin stress principle generated by high-frequency current to heat the edge of hot-rolled coil plate back to the melting state, and then to weld by mechanical extrusion method. A white fusion line will appear in the weld center of the steel pipe produced by the process, and the heat affected zone on both sides of the fusion line will produce a metal streamline extending from the middle to the inner and outer surfaces. Because the base metal is used as the welding material of high frequency steel pipe, the performance of its weld is closely related to the performance of the base metal.

In common materials, the difference of energy absorbed by Charpy impact test between weld and base metal is very small. On the contrary, there is a big difference in the high toughness materials. The impact toughness of the weld is obviously inferior to that of the base metal, but it is obviously superior to that of the common materials. It can be seen that the impact toughness of the weld center of the high frequency steel pipe is generally lower than that of the base metal. Even if the ductile material is used, although the toughness of the weld is improved, the impact toughness of the weld center cannot be completely improved.