ET VS UT Differences Between Ultrasonic Testing UT and Eddy Current Testing ET
Differences Between Ultrasonic Testing (UT) and Eddy Current Testing (ET)
- Ultrasonic Testing (UT): Uses sound waves to penetrate materials, mainly detecting internal defects, even for thick-walled parts.
- Eddy Current Testing (ET): Based on electromagnetic induction, only detects surface and near-surface defects, suitable for conductive metals.
Detailed Comparison Table
| Item | Ultrasonic Testing (UT) | Eddy Current Testing (ET) |
|---|---|---|
| Principle | Reflection/transmission of ultrasonic waves | Alternating magnetic field induces eddy currents; defects change impedance |
| Detection range | Internal, near-surface and surface defects | Only surface and near-surface defects (within a few millimeters) |
| Applicable wall thickness | Suitable for both thick and thin walls | More suitable for thin-walled and small/medium-diameter pipes |
| Material requirements | Good sound conductivity; applicable to stainless steel | Must be electrically conductive; fully applicable to stainless steel |
| Couplant required | Yes (water, oil, etc.) | No, non-contact testing |
| Shape adaptability | Suitable for regular and irregular shapes | Suitable for axisymmetric parts such as pipes and bars |
| Qualification and quantification | Accurate positioning and depth measurement | Fast, but difficult to accurately quantify internal defects |
| Testing efficiency | Relatively slow, suitable for precise inspection | Extremely fast, suitable for high-speed online inspection |
Summary: ET is the fastest and most sensitive for small cracks and minor damages on or near the surface.
