Study on Microstructure and Fatigue Properties of Welding Joints in Vibration Assisted Laser Welding Process

A vibration-assisted laser welding experiment of 4.5 mm industrial pure iron is conducted to focus on the influences of vibration parameters on microstructure, fatigue fracture, and fatigue life. The studies show that the microstructure of the joint is optimized under the condition of 1186 HZ vibration frequency and 36.1 m s(-2) vibration acceleration; it is also found that a suitable microvibration process can enhance the penetration depth of the joints, reduce the number of columnar crystals, and homogenize the microhardness. In high-cycle fatigue experiments, the base material (BM) produces fatigue fracture only under the fatigue load of 52% R-m, the fatigue source area under vibration is at the corner of the fracture or at the inside of the weld seam; a functional consequence is that the vibration can increase the fatigue load strength by 1-3 percentage points, and the fatigue life can be increased by 0.8-1.5 multiples. The microvibration can effectively improve the fatigue performance and increase the fatigue life.