Fracture Failure of 304 Stainless Steel Connectors on the Isolating Switches

The failure mechanism of the connectors assembled on the isolating switches was analyzed. Under SEM examination, the fracture surface showed obvious crack propagation traces. Beach marks with a reverse bending pattern were found on the fracture surface. Fatigue striations, which were the micro-evidence of fatigue, were observed clearly on the propagation zone. Both the metallurgical examinations and XRD analysis showed that the material of the connector only contained the austenite phase. The collected evidence suggests that that failure of the connectors was induced by fatigue. The vibration of the specimen during transport was the most probable source of the alternating stress. The stretching assembly stress of the connector could increase the fatigue stress ratios of the specimen. Defects existing in the material might destroy the continuity of the material substrate and reduce the fatigue performance of the material.