Ultrasonic Scattering And Attenuation Study On Multi-Layers Anisotropic Welds In Remanufacturing Parts

Additive manufacturing technology is an important repair method in the remanufacturing of waste parts.The matel have anisotropic and inhomogeneous microstructure characteristics which produces layer upon layer after repeated heating,melting,cooling and solidification.The anisotropy of microstructure can make ultrasonic wave attenuate and scatter and it is difficult to identify the defect to analyze the result.In order to explore the variation and summarize regularization of ultrasonic wave after suffering the inner anisotropic microstructure,finite element simulation can solve this problem better.In this paper,finite element simulation is used to establish a micro-scale multi-layer anisotropic welding model,carried different frequencies ultrasonic on welding model,so as to explore the influence and the law of regularization iof anisotropic microstructure and frequency on ultrasonic wave.The main work of this paper is as follows:(1)In order to obtain the multi-layer inhomogeneous microstructure of welding beam and doing optical microscope,electron backscattered diffraction and nanoindentation,choose aluminium alloy 5A06 suffering laser cladding,the morphology,distribution and orientation of grain,hardness and elasticity modulus from different measure direction.The experimental results show: in aluminum alloy,the bottom is columnar crystal which growth vertical the fusion,middle part is isometric crystal and dendritic crystal on the top.The bottom is plane crystal which growth vertical the fusion,middle and top is dendritic and afterbirth-like crystal.The hardness and elasticity modulus from horizontal and vertical in different position in welding beam are different,so the welding beam grains are inhomogeneous distribution and microstructure properties are anisotropic.(2)Based on the real inhomogeneous microstructure obtained from the experimental,established micro-scale finite element welding model,using measured elasiticity mudules for input parameter to correct the model.Obtain the influence of ultrasonic wave frequency and anisotropic microstructure after inputting the hanning window ultrasonic wave.(3)Compared the different frequency real experimental wave and simulation wave to verify the finite element welding model,then summarize the anisotropic welding beam to effect the scattering and attenuation regularization.