The high polymer structure of polyethylene materials and the welding process of butt fusion joints determine that the cause of welding defects is the abnormality of molecular structure.In this article,microwave non-destructive testing and result analysis are performed for butt fusion joints,the dielectric characteristic values of defect locations in butt fusion joints are obtained,and destructive tests and fracture scanning electron microscopy analysis are carried out for the defects.Through the microwave non-destructive testing and the macroscopic and microscopic analysis of the fracture surface,it is determined that the mechanism of cold welding defects in butt fusion joints is the absence of molecular long chain structures.Clarifying the types and mechanisms of defects in butt fusion joints helps to carry out effective non-destructive testing and ensure the welding quality of butt fusion joints,providing scientific basis for the safe use of polyethylene pipelines.
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