Nondestructive Evaluation of Weld Defect by Photoacoustic Microscopy and Its Destructive Inspection Using Replica

The nondestructive evaluation (NDE) of a surface crack and an internal defect introduced in the welded region of an aluminum plate has been demonstrated by photoacoustic microscopy. The surface crack and internal defect are a blowhole and an incomplete fusion, which were formed in the weld metal during welding. Experiments were carried out at different modulation frequencies. Furthermore, to gather information on the internal defect, the measurement of the size and shape of the weld defect was carried out by the replica technique. A stereoscopic image of the replica specimen was compared with a photoacoustic (PA) amplitude image.