The magnetic domains in a permanent magnet are aligned in:
C. fixed positions, predominantly in one direction
For which of the following would the wet fluorescent technique be preferred over the dry technique?
B. when increased speed and sensitivity are desired
Gas, misruns, cold laps, and sand inclusions are examples of defects resulting from which of the following processes?
C. castingsd. heat treatment
All of the following are valid reasons for the demagnetization of parts after magnetic particle testing excep that:
C. residual magnetism wil affect the temperature gauges used in subsequent heat treatment
All of the following are valid reasons for the demagnetization of parts after mgnetic particle testing except that:
A. if the part is to be radiographed after magnetic particle inspection, residual magnetism may interfere with the electromagnetic radiation spectrum
Subjecting a part to a magnetic field tht is constantly reversing in polarity and gradually diminishing in strength accomplishes which of the following?
B. the part becomes demagnetized
The concentration of the solid contenet of a suspension of magnetic particles is measured by:
B. permitting the solids to settle out of suspension
An important factor that must be considered when selecting a method of magnetization is:
D. both b and c
An important factor that must be considered when selecting a method of magnetization is:
D. both a and b
What happens to a magnetic material when it reaches its Curie temperature?
B. it becomes nonmagnetic
A material that is repelled by magnetism is:
a: diamagnetic
b. ferromagnetic
c. paramagneticd. overtly magnetic
a: diamagnetic
Materials weakly attracted by magnetic fields are:
B. paramagnetic
Methods used to preserve powder patterns include:
D. all of the above
Magnetic particle inspection methods are recognized as superior to liquid penetrant techniques when:
D. both a and c
. What magnetic property does a paranmagnetic mterial possess?
A. is slightly magnetic
In what way can a magnetic field be reduced?
D. all of the above
When the external magnetizing force has been removed, some of the magnetic domains remain preferentially oriented. The additional force required to reurn them to their original random orientation is commonly referred to as:
C. coercive force
When a cylinder is being magnetized by central conductor, the field is most intense:
D. at the inside surface of the cylinder
When is the magnetic field strongest in an object being inspected by the magnetic particle method?
A. while the magnetizing current is applied
Which of the demagnetization methods listed below is most effective?
A. DC with reversing and step-down control
When using the longitudinal magnetization method to inspect a bar 152mm (6in) long and 51mm (2in) in diameter with a 5-turn coil, which of the following amperage values should be used?
A. 3,000 amps
To examine a part 127mm (in) long and 51mm (2in) in diameter using a 5-turn coil and head-stock magnetic particle machine, what amperage should be used for longitudinal magnetization?
C. 1,800 amps
To examine a bar 38cm (15in) long and 51mm (2in) in diameter using a 7-turn coil and head-stock magnetic particle machine, what amperage will be used for circular magnetization?
A. 1,800 amps
If the same amperage is passed through a 25mm (1in) and a 51mm (2in) diameter bar of the same length, which of the following statements is most applicable relevant to the magnetic field at the surface of the bars?
B. the strength of the magnetic field at the surface of the 25mm (1in) bar will be approximately twice that of the 51mm (2in) bar
If the same amperage is passed through a 25mm (1in) diameter bar and a 51mm (2in) diameter bar of the same length, which of the following statements is most applicable relevant to the magnetic field at the center of the bars?
D. the strength of the magnetic field in the center of both bars will be zero
When a magnetic field is induced in a part with prods spaced 152mm (6in) apart, the field is a:
C. distorted circulr field
When circular magnetization is used and it is important to detect subsurface defects, direct current is used instead of alternating current because:
A. the skin effect of AC reduces the maximum depth at which defects can be found
An inspection method in which a high magnetizing force is applied to a part, and the force is then reduced to a lower continuous value which is maintained during application of the inspection medium is called the:
D. surge method
When deciding to inspect a part by the residual method, the strength of the residual field in the part should be considered. Factors that afffect this field include:
D. all of the above
. Factors that must be considered when interpreting an indication are:
D. all of the above
When thorough demagnetization is to be accomplished by placing the part in a coil energized with AC of decreasing amperage, the following orientation of the long axis of the part is most advantageous:
A. East-West
A 7-turn coil at 1,000 amps is used to inspect a round solid part 38cm (15in) long and 64mm (2-1/2in) in diameter. What is the L/D ratio?
C. 6
. Which of the following, when used as the last magnetizing method, will best render a part suitable for relatively easy measurement of the external magnetic field using a field indicator?
B. longitudinal magnetization
. When using DC, an indication is detected. What is the next logical step to determine if the indication results from a surface or subsurface condition?
D. reinspect using AC
Which of the statements made below is most appropriate concerning materials I and II represented by the hysteresis curves shown in Figure 1?
C. material II could be used for dry powder magnetic particles
The curve shown in Figure 1 for material II indicates that it:
D. has a high permeability
Point B on the hysteresis curve for material I shown in Figure 1:
D. is the material's magnetic saturation point
Which point on the hysteresis curve shown in Figure 1 represents the residual field value?
C. C
When withdrawing a part from the field around a coil and without changing the direction of current, which of the following has the least effect on demagnetizing the part?
A. direct current
An important factor that should be considered when selecting a method of magnetization is:
D. all of the above
Which of the following discontinuities occur as a result of the roling process?
B. laminations
Which of the folowing discontinuities occur as a result of the forging process?
B. laps
If an indication is formed when using the residual method as well as the continuous method, it is most likely:
D. a relevant indication
Plated parts can be reliably tested using the magnetic particle method if the plating is less than:
A. 0.1mm (0.004in) thick
The magnetic lines of flux or flux in a permanent magnet:
B. enter the south pole and leave the north pole
Which of the following magnetization techniques should be avoided when performing magnetic particle testing?
B. parallel magnetization
Banding is a common term used to describe:
D. powder patterns created by using excess amperage
When attempting to demagnetize a part containing a circular residual field:
A. establish a longitudianl field and then proceed with demagnetization
The input current requirements for MT equipment depend in part upon the:
C. duty cycle required
Small parts requiring demagnetization should be:
A. processed through a demagnetization cycle one at a time
The best shape for magnetic particles used in the dry powder method is:
B. a mixture of b and c
52. The best method for testing ball bearings is:
a. along one axis using a coil
b. two shots using a coil at the X and Y axis
c: Two head shots along the X andY axis
d. induced current shots along X, Y, and Z axis rotating 360 degrees during each shot
d. induced current shots along X, Y, and Z axis rotating 360 degrees during each shot
