Research on Ultrasonic Array Testing Methods of Laser Additive-manufacturing Titanium Alloy

Laser additive manufacturing(AM) technology of titanium alloy has been gradually applied to rapid prototyping of complex components in aerospace and other fields. However, due to the high attenuation and inhomogeneity caused by its special manufacturing process, it is inefficient and poor imaging results to detect its internal defects by conventional ultrasonic testing methods. For this reason, the key technologies of ultrasonic array method in the detection of additive-manufacturing titanium alloy are studied. A TC18 titanium alloy specimen is prepared by laser AM method, the ultrasonic attenuation characteristics of the specimen are analyzed based on the high frequency ultrasonic immersion method, and the internal echo imaging method for AM titanium alloy components is proposed as well. The variation trends of ultrasonic group velocity in the specimen with different propagating angles are measured using full matrix capture method of linear array transducer. In addition, the anisotropy of the AM titanium alloy is summarized and the ultrasonic array imaging algorithms are corrected based on the measurement results. Finally, the C scan detection experiments are conducted on the specimen by using the linear array and the annular transducer respectively, and the main factors that affect the test result are analyzed. The results show that the internal defects of the AM titanium alloy specimen can be more accurately characterized using the annular array transducer with the total focusing method(TFM), and it has a good application prospect in the nondestructive testing of the AM titanium alloy components.