Laser ultrasonic inspection of laser cladded 316LSS and TI-6-4

Abstract

Laser ultrasonics shows great promise for on-line monitoring of product integrity in a number of industrial laser processes, including welding and cladding. In the laser cladding process, we wish to detect defects on each clad layer as it is being deposited. The defect information can be then used to control critical weld parameters or alert the operator of a problem requiring maintenance. In this way, defects can then be corrected before many defective parts are produced.Laser ultrasonics uses a pulsed laser to generate an ultrasonic wave and a continuous-wave laser interferometer to detect the small surface displacement when this wave arrives at the point of detection. Laser ultrasonics is ideal for in-line measurements because there is no sensor in contact or near-contact with the workpiece. In addition, measurements can be performed on curved surfaces and in areas that are difficult to access.In this study, we have used laser-generated surface waves to interrogate laser cladded parts in both stainless steel and Ti. We have used wavelet analysis to separate the temporal signals and select the distinguishing features that are most sensitive to defect presence. The processing approach was optimized using simulated pores produced using blind holes.Laser ultrasonics shows great promise for on-line monitoring of product integrity in a number of industrial laser processes, including welding and cladding. In the laser cladding process, we wish to detect defects on each clad layer as it is being deposited. The defect information can be then used to control critical weld parameters or alert the operator of a problem requiring maintenance. In this way, defects can then be corrected before many defective parts are produced.Laser ultrasonics uses a pulsed laser to generate an ultrasonic wave and a continuous-wave laser interferometer to detect the small surface displacement when this wave arrives at the point of detection. Laser ultrasonics is ideal for in-line measurements because there is no sensor in contact or near-contact with the workpiece. In addition, measurements can be performed on curved surfaces and in areas that are difficult to access.In this study, we have used laser-generated surface waves to interrogate laser cladded parts in both stainless...