Non-destructive testing of interfacial stiffness based on spring model for diffusion bonding interface of titanium alloy components with complex surface

Ultrasonic testing is an important non-destructive testing method, which is sensitive to the defects in the diffusion bonding interface. Ultrasonic testing of diffusion bonding interfaces in complex-surface components is a challenge due to the geometry and the weak echo signal of the diffusion bonding defects. This paper proposes an interfacial stiffness characterization method based on the spring model for the ultrasonic testing of the diffusion bonding interface of titanium alloy complex-surface component. Finite element models for ultrasonic field are established to analyze the diffusion bonding defects response, the effect of complex surface, and the inconsistency of the bonding interface depth in ultrasonic testing of the titanium alloy complex-surface component. 15 MHz is recommended as the testing frequency of the diffusion bonding interface. Ultrasonic C-scan experiments are conducted using specimens with embedded artificial defects and a titanium alloy complex-surface component. The simulation and experimental results show that the novel interfacial stiffness characterization method can be applied to ultrasonic testing of the diffusion bonding interface (inclination angle less than 14°) in complex-surface components, and the ability to test defects at the diffusion bonding interface can be improved.