Analysis of streak defects on the surface of high-quality automobile steel SP121 after stamping

Aiming at the streak defects on the surface of high-quality automobile steel SP121 after stamping, the surface profile of the streak defects was analyzed by a confocal laser scanning microscope (CLSM). The micro-morphology and element content of the streak defects area were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that compared with the normal area of the strip steel surface, the surface roughness features of the streak defects area of SP121 after stamping are not apparent. There are many linear defects and dot defects perpendicular to the streak defects. The energy spectrum detection shows no element abnormality in the streak defects area. The surface streak defects of SP121 after stamping are caused by the poor contact between the strip steel and the stamping die, which leads to the poor fluidity of the materials during stamping, and finally, the streak defects are formed.