Effect of ultrasonic impact on the surface microstructure and fatigue properties of welded cross joint for train bogie

Surface treatment was carried out on the weld toe of welded 16MnR cross joint of train bogie with HJ2-Ⅱ type ultrasonic impact machine. The microstructure of treated surface of weld toe was observed with HRTEM. The fatigue test was performed on both as-welded and treated 16MnR joints with EHFEM200K2- 070-1A type fatigue tester. The experimental results show that the nano-microstructure was obtained in the surface of weld toe and its nearby area. The joints before and after ultrasonic impact fractured through the weld toe. The conditional fatigue limits (2×10⁶) of the welded and treated joints were about 158 MPa and 236 MPa,respectively. The conditional fatigue limit increased by 49% and the fatigue life improved by 45-52 times. The ultrasonic impact treatment has significant effect on improving the fatigue life of 16MnR cross joint for train bogie.