Interface Integrity Evaluation of Explosively Welded Metallic Structures

Explosively bonded tubes have been applied in high pressure and high temperature environments, such structures are usually consisting of dissimilar metals which are very difficult to be welded together by other conventional welding methods. In this study, various experimental techniques were used for the evaluation of interface integrity between steel major tube and tantalum donor tube. First, X-ray diffraction technique was used to profile the residual stress levels in the tantalum donor tube before bonding and steel major tube after bonding, especially the hoop stress level which is critical to quality control. Also, other experimental techniques including digital microscopy for interface geometrical features, X-ray fluorescence spectroscopy for interface compositions, and nano-hardness testing for materials strength at micro/nano scale were further applied to explain bonding mechanisms and to quantify bonding interface conditions. Then nondestructive ultrasound C-scan technique was used to create acoustic images of the bonding interfaces and the results showed that the technique has the potential to find weak interface and to further quantify good and poor bonds. Finally, destructive testing techniques were used to measure the interface shear and tensile strength and to study the interface failure mechanisms, and the results agree well with other experimental techniques.