Free ASNT Eddy Current Questions and Answers

Question 1

A method of minimizing the effect of indications caused by gradual dimensional changes while retaining the indications caused by discontinuities is to:

Accepted Answer

Include a high pass filter in the eddy current test equipment

Answer

Explanation:
Including a high pass filter in the eddy current test equipment allows the system to filter out low-frequency signals, which are typically associated with gradual dimensional changes, while retaining high-frequency signals, which are indicative of discontinuities. This helps minimize the effect of gradual dimensional changes while focusing on detecting relevant indications of defects.

Question 2

Which of the following methods may be used to improve the signal-to-noise ratio of an eddy current test system?

Accepted Answer

All of the above

Answer

Explanation:
All of the methods listed—filtering or differentiation, phase discrimination, and integration—can be used to improve the signal-to-noise ratio of an eddy current test system. Filtering or differentiation helps in separating relevant signals from noise by filtering out unwanted frequencies or by differentiating the signal. Phase discrimination involves comparing the phase of the reference signal with that of the test signal to enhance sensitivity to changes in material properties. Integration can improve signal quality by summing up signal values over time to enhance the detectability of small changes in the signal.

Question 3

In order to decrease the effect on conductivity readings due to variations in test part thickness:

Accepted Answer

The test frequency should be increased

Answer

Explanation:
To decrease the effect on conductivity readings due to variations in test part thickness, increasing the test frequency is a practical method. Higher frequencies are less affected by changes in material thickness compared to lower frequencies. Therefore, increasing the test frequency helps minimize the influence of variations in test part thickness on conductivity readings.

Question 4

When testing by the eddy current method, discontinuities will be most easily detected when the eddy currents are:

Accepted Answer

Perpendicular to the major plane of the discontinuity

Answer

Explanation:
Discontinuities will be most easily detected when the eddy currents are perpendicular to the major plane of the discontinuity. This orientation maximizes the interaction between the eddy currents and the material, leading to more significant changes in the impedance or other parameters being measured by the eddy current testing equipment.

Question 5

A term used to describe the effect observed due to a change in the electromagnetic coupling between a test specimen and a probe coil when the distance of separation between them is varied is:

Accepted Answer

Lift-off

Answer

Explanation:
Lift-off is the term used to describe the effect observed due to a change in the electromagnetic coupling between a test specimen and a probe coil when the distance of separation between them is varied. This effect can influence the signal response in eddy current testing and needs to be carefully managed to ensure accurate results.

ASNT - American Society for Nondestructive Testing, Inc. Practice Test

ASNT - American Society for Nondestructive Testing, Inc. Practice Test

Free ASNT Eddy Current Questions and Answers