Causes of fracture of lifting ring screw

A lifting ring screw fractured in the process of elevator installation. The fracture reasons were analyzed by means of macroscopic observation, chemical composition analysis, mechanical property test, scanning electron microscope and energy spectrum analysis, metallographic examination and so on. The results show that there were cracks in the screw before electroplating. The existence of the cracks destroyed the continuity of the screw, reduced the strength of the screw, and caused the screw to break during the hoisting process.