Effects of multidimensional vibration on laser cladding of SS316L alloy

Abstract

As a widely-used approach for surface modification, laser cladding plays a significant role in aerospace, turbine and other fields. However, the defects usually existing in laser cladding parts, such as pores, cracks, tensile residual stress, significantly affect the performance and the application of the cladding parts. In this study, SS316L alloy layer was fabricated on 45 steel substrate using laser cladding process assisted by multidimensional vibration. By changing the vibration direction, the microstructures and the properties of the coating and the bonding interface with various vibration parameters were analyzed and compared. The microstructures of the cladding layer and the matrix were analyzed by an optical microscope and a scanning electron microscopy (SEM). The results show that the multidimensional vibration is able to refine the columnar dendrites formed in the cladding layer. The transient excitation generated by the vibration enhances the convection of the molten pool in the solidification process, breaks the dendrite arm, and increases the nucleation rate. Meanwhile, affected by the multidimensional vibration, the porosity and the maximum pore size of the cladding layer significantly reduced. The tests of the microhardness distribution showed that the the average microhardness of the cladding layer significantly increased and the microhardness fluctuation decreased assisted by the multidimensional vibration. Experimental results also demonstrate that the effects of the three-dimensional vibration are more significant than the single vertical vibration. The proposed approach provides a potential way to improve the laser cladding process.