Quality-control of laser welds of tailored blanks using guided waves and EMATs

In modem design of automobile bodies reduction in weight and maximization of the structural stiffness and passive safety are the main challenge. For an essential reduction in weight the 'Tailored Blank' has contributed. The single flat sheets are joined by Laser Welding (butt weld). Usually the quality of the welds is assured by precise preparation of the plate edges as well by a couple of process parameters. However due to deviations typical defects occur, which make NDT necessary to detect defects as incomplete welding, lack of fusion, misalignment of the weld, holes and porosity. Conventional UT is ruled out because of the necessary liquid coupling medium. Dry UT by EMAT's can solve this task.