Time-of-Flight Diffraction Signal Evaluation
Time-of-flight diffraction signal evaluation is an ultrasonic testing method that measures the time-of-flight of diffracted waves at crack tips to determine their depth and size. The evaluation analyzes phase changes in the interference pattern.
Physical-Chemical Mechanism of Action
TOFD signal evaluation measures the travel time of ultrasonic waves reflected at crack tips in a material. This travel time is proportional to the crack depth. Phase changes in the interference pattern give information about crack size and shape.
Metallurgical Relevance & Welding Risks
This method is especially useful for precise depth determination of microcracks and flaws in weld areas. Misinterpreting the signals can lead to inaccurate results, which poses risks in the material testing process.
Shop Practice & Action Steps
To perform TOFD signal evaluation correctly, follow these steps:
1. Set up the equipment: Make sure the ultrasonic unit is properly calibrated and the sensors are clean.
2. Inspect the weld: Apply the ultrasonic beam to the weld and collect the diffracted wave signals.
3. Analyze the signals: Examine the interference pattern to detect phase changes and derive crack depth and size from them.
4. Document the results: Record all measured values and your interpretations for traceable documentation.