Fractographic Analysis of Impact Fracture Surface for Pipeline Steels

In order to search how the material properties and microstructure distribution affect the impact absorption energy, pendulum impact tests were carried out on pipeline steel samples of different grades. The propagation of inclusions, microstructure deformation and secondary crack propagation at the impact fracture surface during impact were analyzed by optical microscope and scanning electron microscope. The results show that the impact absorption energy was more closely related to the maximum tensile stress and the ability of uniform plastic deformation. The ability of the spherical inclusions to form cracks and expand during impact was weak. The quasi-polygonal ferrite in the pipeline steels has good blocking effect on crack propagation.