Fatigue Failure Analysis and Microstructural Characterizations on Flash Butt Welded Joint of Automotive Steel Wheel Rim.

The quality of wheel rims has a strong impact to vehicle safety and reliability during steering. The objective of this work is to reveal the fatigue failure mechanism of the radial fatigue fracture in the flash butt welded joint of 590CL HSLA steel. Morphology and fractography were performed to analyze the microstructure and fatigue crack surface of the wheel rim. The results show that the fatigue crack is located near the region of rim-well radius where the thickness variation and stress level are relatively high. By means of microstructure comparative analysis of the flash butt welded joint on both failed rim and qualified rim, the cause of the fracture is mainly attributed to heat input of the flash butt welding process. [ABSTRACT FROM AUTHOR]