Effect of Vibration Frequency on Laser Filler Wire Welded Joints

Abstract

The effects of different vibration frequencies on the microstructure, residual stress, and fatigue life of welded joints are investigated using laser filler wire welding combined with mechanical vibration. The results show that the vibration frequency of 1055 Hz has a significant effect on the melting width of the laser welding with filler wire joint. The welds have three morphological features of columnar crystals, dendrites, and equiaxed crystals. In addition, the welds with 1055 Hz vibration frequency have the most equiaxed crystals and the highest hardness. The vibration frequency of 524 Hz increases the residual stress of the welded joint by 16%, whereas the vibration frequency of 1055 Hz reduces its residual stress by 8%. It can be shown by tensile experiments that the laser filler wire–welded joints have a higher tensile strength and greater elongation with increase in the vibration frequency. The fracture observation shows that the cleavage step appears in the crack propagation zone. Compared with the vibration frequency of 524 Hz, fatigue fracture at the 1055 Hz vibration has narrower fatigue striation spacing, lower crack growth rate, and higher fatigue life.