Detection method for microcracks in cemented carbide plates based on ultrasonic Lamb waves

When there are microcracks inside the cemented carbide, they will affect its service life. Lamb waves are often used for nonlinear ultrasonic nondestructive testing, and they are widely used in the detection of microcracks in aluminum plates, but for cemented carbide, due to its large absorption coefficient, the nonlinear effect is not obvious enough. Therefore, this paper studies the methods of increasing the nonlinear coefficient interaction between Lamb waves and cemented carbide, and the method of locating microcracks, to achieve microcrack detection of cemented carbide based on ultrasonic Lamb waves. A three-dimensional detection model of cemented carbide plate is established using the COMSOL Multiphysics simulation software, and the simulation experiments of microcrack length and width are carried out. The experimental results show that the nonlinear coefficient increases as the length of the microcrack becomes longer and decreases as the width of the microcrack becomes wider. The smallest carbide microcrack that can be detected is 0.2 mm in length and 0.04 μm in width, and the positioning error is within 2 mm.