Ultrasonic Characterization of Microstructures in Inertia Friction Welds on SiC-Reinforced 8009 Aluminum

摘要

The microstructures of inertia-friction welds (IFRWs) on an aluminum metal matrix composite have been investigated using several ultrasonic examination (UE) techniques as well as standard characterization methods. This study represents one of the first efforts to utilize UE methods for mi-crostructural characterization of welds. The flow line patterns and dimensions of the different weld zones in IFR welds on a SiC-reinforced 8009 aluminum composite (8009/SiC/11p) have been determined using optical microscopy (OM) and scanning-electron microscopy (SEM) as well as the following UE methods: 1) acoustic microscopy, 2) C-scan imaging, 3) axial backscattering, and 4) radial backscattering. The UE techniques exploited the variations in ultrasonic scattering produced by changes in the distribution of the SiC particles. The ultrasonic procedures allowed rapid determination of microstructural features in the IFR welds. The acoustic microscopy technique provided detailed pictures of the flow lines in longitudinal sections of the welds, as well as the dimensions of the different weld zones as functions of radial position. Ultrasonic C-scan imaging determined the flow line patterns in thin disks centered at different axial distances from the weld centerline. The C-scan imaging technique also revealed the presence of purposely induced defects that resulted from lack of bonding near the axial centerline of one of the welds. Axial ultrasonic backscat-tering measurements were used to determine the widths of the various weld zones as functions of radial position. Finally, radial ultrasonic backscattering measurements provided the overall widths of the entire weld zone at a fixed radial position.