Causes of cracks during bend process

　　Causes of cracks during bend process: defects and protection microcracks generated during medium frequency bending. When induction heating bend steel pipe, microcracks will be generated on the outside of the bend when the deformation temperature and deformation of a certain level are exceeded. Both of these conditions are related to the material of the bend pipe. Under the similar forming conditions of low deformation speed and high tension resistance, all bending construction of the pipe bend under this condition may produce such data damage. The domestic pipe bending market continued to decline. At the end of the month, there were signs of acceleration due to the broken position of pipe bend processing price. The social inventory of pipe bend continued to go through the process, and the Lange composite index closed below the 140 level.

　　As for microcracks, we stop the discussion with grain boundary cracks. According to the forming conditions, the crack length is generally reachable. The cracks mainly occur on the austenite grain boundary perpendicular to the stress direction, so they are also perpendicular to the slag inclusion of the extended pipe. After the welded pipe is bent, the microstructure is recrystallized by heat treatment, so that the microcrack changes into crystal.