Cause Analysis on Unqualified Tensile Failure Load of Insulator Steel Foot

Insulator steel foot with strength grade 530 MPa requires a tensile failure load of not less than 615 kN. Insulator steel foot manufactured by a company was broken when the load reached 513 kN during the tensile failure load test. By means of fracture analysis, chemical composition analysis and metallographic examination, the causes of unqualified tensile failure load of insulator steel foot were analyzed. The results show that folding defect occurred at the junction of the ball head and the rod when the insulator steel foot was processed and forged. The folding defect were brittle cracks due to the large stress in the tensile failure load test, which eventually led to the fracture of the insulator steel foot.