1989 Volume 7 Issue 4 Pages 518-524
In this study, an improved technique of ultrasonic testing with an immersion-type focusing probe is applied to various types of soldered lap joints of copper and brass thin sheet of 0.3 to 1.0 mm in thickness. This method is based on a composite effect of convergence of ultrasonic beam and its attenuation due to multiple reflections between surface and near surface flaw. The sound soldered region is evaluated by the appearance of backwall echo or interface echo on the oscilloscope screen and echo height variation on scanning graphs. Moreover, the echo height topography and C-scan colour display are tried to image the soldered region.
The results show that by this method, it is able to distinguish between surface echo, interface echo within the non-soldered region and backwall echo within the sound soldered region, since the interface echo produces higher amplitude than the backwall echo. Although solder affects the echo pattern, its effect on the echo height is minor. The echo height topography and C-scan colour display both deduced from scanning detection of this process indicate an image of the soldered region precisely.
