Podcast
Questions and Answers
Variations in the chemical composition of a non-ferromagnetic alloy would have the most effect on its:
Variations in the chemical composition of a non-ferromagnetic alloy would have the most effect on its:
Conductivity
A reference sample used to ensure that the amplitude and phase characteristics of a test system do not drift during continuous testing is called a:
A reference sample used to ensure that the amplitude and phase characteristics of a test system do not drift during continuous testing is called a:
Calibration standard
A term used to define a standardized condition in a device or system which results in zero output shown across a bridge circuit is:
A term used to define a standardized condition in a device or system which results in zero output shown across a bridge circuit is:
Null or Balance
The phenomenon referred to when inspecting products with a uniform cross section and an eddy current signal is produced due to the edge of the product approaching the test coil is called:
The phenomenon referred to when inspecting products with a uniform cross section and an eddy current signal is produced due to the edge of the product approaching the test coil is called:
Signup and view all the answers
The use of ferromagnetic shielding materials around the AC Coil will generally:
The use of ferromagnetic shielding materials around the AC Coil will generally:
Signup and view all the answers
Eddy current testing can penetrate up to 2 inches in a test part.
Eddy current testing can penetrate up to 2 inches in a test part.
Signup and view all the answers
Eddy current always travels:
Eddy current always travels:
Signup and view all the answers
Eddy currents cannot be induced in paint.
Eddy currents cannot be induced in paint.
Signup and view all the answers
Which condition would be the most difficult to detect when using an eddy current testing rod with an encircling coil?
Which condition would be the most difficult to detect when using an eddy current testing rod with an encircling coil?
Signup and view all the answers
When conducting an eddy current test using a coil arrangement that compares an external reference standard with the specimen, the system should be nulled or balanced:
When conducting an eddy current test using a coil arrangement that compares an external reference standard with the specimen, the system should be nulled or balanced:
Signup and view all the answers
During an eddy current test, discontinuities will be most easily detected when the eddy currents are:
During an eddy current test, discontinuities will be most easily detected when the eddy currents are:
Signup and view all the answers
An eddy current system is least sensitive to discontinuities that:
An eddy current system is least sensitive to discontinuities that:
Signup and view all the answers
A term used to describe a hole, groove, or notch that is machined into the reference standard to provide accurately reproducible quality level is:
A term used to describe a hole, groove, or notch that is machined into the reference standard to provide accurately reproducible quality level is:
Signup and view all the answers
A term used to define one or more turns or loops of a conductor wound in such a manner as to produce an axial magnetic field when current passes through the conductor is:
A term used to define one or more turns or loops of a conductor wound in such a manner as to produce an axial magnetic field when current passes through the conductor is:
Signup and view all the answers
A test coil's opposition to the flow of alternating current is called:
A test coil's opposition to the flow of alternating current is called:
Signup and view all the answers
Non-destructive tests aren't conducted to assure large volumes of material are available for sale.
Non-destructive tests aren't conducted to assure large volumes of material are available for sale.
Signup and view all the answers
Determining the instrument control settings needed to pass the highest percentage of the test specimens run is a primary purpose for using a reference standard.
Determining the instrument control settings needed to pass the highest percentage of the test specimens run is a primary purpose for using a reference standard.
Signup and view all the answers
In order to decrease the effect on conductivity readings due to variations in test part thickness:
In order to decrease the effect on conductivity readings due to variations in test part thickness:
Signup and view all the answers
Which product forms would be most applicable to a test using an inside coil?
Which product forms would be most applicable to a test using an inside coil?
Signup and view all the answers
The process of comparing the reading or output of an instrument, device, or dial with a standard to determine the instrument's accuracy, capacity or graduation is referred to as:
The process of comparing the reading or output of an instrument, device, or dial with a standard to determine the instrument's accuracy, capacity or graduation is referred to as:
Signup and view all the answers
A symbol commonly used to describe permeability:
A symbol commonly used to describe permeability:
Signup and view all the answers
A change in probe speed will alter the impedance of the coil.
A change in probe speed will alter the impedance of the coil.
Signup and view all the answers
An eddy current coil arrangement that does not make a comparison with either two sections of the test specimen or one section of the test part and a reference standard is called:
An eddy current coil arrangement that does not make a comparison with either two sections of the test specimen or one section of the test part and a reference standard is called:
Signup and view all the answers
The impedance of a test coil will increase if the:
The impedance of a test coil will increase if the:
Signup and view all the answers
An eddy current test makes use of electrical current induced in a conductive article by:
An eddy current test makes use of electrical current induced in a conductive article by:
Signup and view all the answers
Frequency would not be considered to be a material property.
Frequency would not be considered to be a material property.
Signup and view all the answers
Determining the exact chemistry of an alloy is not a common application for eddy current testing.
Determining the exact chemistry of an alloy is not a common application for eddy current testing.
Signup and view all the answers
Which of the following frequencies will provide the greatest eddy current penetration in aluminum?
Which of the following frequencies will provide the greatest eddy current penetration in aluminum?
Signup and view all the answers
Study Notes
Eddy Current Testing NDT Overview
- Variations in chemical composition of non-ferromagnetic alloys primarily affect conductivity.
- A calibration standard ensures amplitude and phase stability in testing systems.
- "Null or Balance" refers to a condition in a device where no output is shown in a bridge circuit.
Key Principles and Effects
- The edge effect occurs when an eddy current signal is produced as the leading or trailing edge of a product approaches the test coil.
- Ferromagnetic shielding around AC coils decreases magnetic field extension and limits eddy current penetration.
- Eddy currents consistently travel in closed paths and cannot be induced in materials like paint.
Detection Limitations and Sensitivity
- Small inclusions in the center of a test rod are difficult to detect using encircling coils.
- The system should be nulled or balanced by comparing a reference standard with an acceptable test specimen.
- Eddy currents are most easily detected when they are perpendicular to the main dimension of any discontinuity.
Discontinuities and Sensitivity Analysis
- Eddy current systems are less sensitive to discontinuities that are aligned with the flow of eddy currents.
- Artificial discontinuities are machined into reference standards for reproducible quality levels.
- Increased test frequency reduces the effect of material thickness on conductivity readings.
Coil Design and Function
- A coil is defined as a conductor that produces an axial magnetic field when current passes through it.
- Impedance measures a test coil's opposition to the flow of alternating current.
- Absolute coil arrangements do not compare the test specimen with a reference or another section.
Application and Limitations
- Non-destructive tests do not aim to assure large volumes of material are available for sale.
- Reference standards primarily ensure accuracy and consistency, not instrument control settings for test specimens.
- Eddy current testing is not used for determining the exact chemistry of alloy materials.
Frequency and Material Response
- A frequency of 300 kHz provides the greatest eddy current penetration in aluminum.
- Test variables, such as probe speed changes, do not alter coil impedance.
- Permeability is represented by the symbol µ, an important property in testing.
Miscellaneous
- Calibration checks the accuracy and performance of instruments against standards.
- Eddy current testing relies on an alternating magnetic field to induce currents in conductive materials.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge with these flashcards focused on Eddy Current Testing in Non-Destructive Testing (NDT). Each card presents terms and definitions essential for understanding the core concepts and applications of NDT techniques. Perfect for students and professionals looking to reinforce their learning.
