Effect of Vibration Frequency on Microstructure and Properties of Laser-Welded Inconel 718 Nickel-Base Superalloy

Abstract

The effects of different vibration frequencies on the microstructure, laves phases and microvoids of Inconel 718 weld joints were investigated in this research by using the laser welding combined with mechanical vibration. The results demonstrated that the application of vibration significantly suppressed the growth of columnar crystals, reduced the formation of carbides, and refined the microstructure. With the increase of the vibration frequency, the mechanical vibration stayed prominent. The molten pool was subjected to the pressure and vibration of the metal liquid, which expanded the depth and the width of the weld. Applying vibration could reduce the amount of Laves phase, and it is found that with the increase of vibration frequency, the morphology of Laves phase could change from granular to strips, as found during the experiment. The welds with 522 Hz vibration frequency had the smallest Laves phase size and the largest average microhardness value of 331 HV. At the vibration frequency of 1331 Hz, the amount of Laves phases was the least, and it was distributed in a miscellaneous manner in the form of granules and stripes. However, increasing the vibration frequency could not effectively reduce the number of microvoids in the weld.