Nonlinear Ultrasonic C-Scan Imaging for Contact-Type Defects in Diffusion-Bonded Joints-A Case Study

Area of Science:

• Materials Science and Engineering
• Non-Destructive Testing
• Ultrasonic Characterization

Background:

• Diffusion bonding is crucial for precision components, but detecting interface defects is challenging.
• Existing nonlinear ultrasonic methods have limitations in excitation signals, restricting broader application.
• Linear ultrasonic testing struggles with detecting subtle contact-type defects.

Purpose of the Study:

• To propose and validate a dual-probe nonlinear ultrasonic testing method with pulse wave excitation.
• To enhance the detection of contact-type defects in diffusion-bonded joints.
• To develop a nonlinear ultrasonic C-scan imaging technique for bond interfaces.

Main Methods:

• Fabrication of a titanium alloy diffusion-bonded specimen with artificial defects.
• Design of a detection device integrated with an ultrasonic C-scan system.
• Development of a C-scan imaging program extracting fundamental and second harmonic waves for nonlinear parameter calculation.

Main Results:

• Successful acquisition of nonlinear parameters for diffusion-bonded interfaces.
• Generation of nonlinear ultrasonic C-scan images of the bond interface.
• Nonlinear parameters in contact-type defect areas were approximately 10 times (20 dB) higher than in macro defect areas (10 μm gap).

Conclusions:

• The proposed dual-probe nonlinear ultrasonic method effectively detects contact-type defects in diffusion-bonded joints.
• Nonlinear ultrasonic testing demonstrates superior sensitivity to subtle defects compared to linear methods.
• This technique shows great potential to augment the detection capabilities for diffusion-bonded components.