Assessment and Characterization of Welded Mild Steel (E-6013) Using Ultrasonic Testing and Hilbert Huang Transform

All welded parts undergo aging once operated at elevated temperatures. Exposures of structures on elevated temperatures adversely affect the material performance and deteriorate the structure’s toughness. The welded part also develops the high risk of brittle fracture. In order to establish the fracture toughness, it is not always possible to remove the specimen from the service. Therefore, it is desirable to develop an in situ non-destructive testing (NDT) based on ultrasonic testing (UT) method along with advanced signal processing techniques. Ultrasonic testing is an extensively used Non-destructive testing technique that offers improved damage detection capability. The objective of the study is to found a quantitative relation between UT and mechanical properties of welded joint heat treated specimens. The data was acquired from the testing of weld specimens at different levels of temperatures through ultrasonic testing. There is a trend observed between the variation in the UT signal’s characteristics i.e. attenuation and the variation in the mechanical properties. The possible categorization of UT signal in terms of different thermal aging levels has also been explored using Hilbert Huang transform (HHT) on acquired UT signals. The experimental relationships will enable welded specimen toughness prediction solely through in situ ultrasonic testing while the specimen will remain in service.