Level III Questions Magnetic Particle Testing Method Flashcards
- The magnetic domains in a permanent magnet
are aligned in:
a. fixed positions with directions that cancel out.
b. fixed positions, predominantly in one
direction.
c. the same diction as the metal’s grain
structure.
d. a random position and may become aligned to
attract a magnetic material.
b. fixed positions, predominantly in one
direction.
- For which of the following would the wet
fluorescent technique be preferred over the dry
technique?
a. When the parts are large and bulky.
b. When increased speed and sensitivity are desired.
c. When the parts being inspected are to be field
welded.
d. When it is desired to use the fluorescent
lighting provided in many plants.
b. When increased speed and sensitivity are desired.
- Gas, hot tears, cold shuts, shrinkage cracks and sand inclusions are examples of defects resulting from which of the following processes?
a. forging
b. grinding
c. casting
d. heat treatment
c. casting
- Which of the following statements is a valid reason for demagnetizing a part after completing
a magnetic particle test?
a. Residual magnetism can disturb the welding
arc path on parts to be welded.
b. Residual magnetism may attract chips or small
particles in-service, causing galling or
mechanical wear.
c. Residual magnetism could interfere with the
operation or accuracy of instruments placed on
or near the part during service.
d. If the part is to be radiographed after magnetic
particle inspection, residual magnetism may
interfere with the electromagnetic radiation
spectrum.
d. 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 that is
constantly reversing in polarity and gradually
diminishing in strength accomplishes which of
the following?
a. Magnetizes the part.
b. Demagnetizes the part.
c. Helps to locate deep-laying defects.
d. Increases the strength of the retained magnetic
field.
b. Demagnetizes the part.
- The concentration of the solid content of a
suspension of magnetic particles is measured by:
a. weighing the suspension.
b. soaking the solids in benzol.
c. measuring the pull on a magnet.
d. permitting the solids to settle out of
suspension.
d. permitting the solids to settle out of
suspension.
- An important factor that must be considered
when selecting a method of magnetization is the:
a. part’s curie point.
b. the location of the inspection station.
c. location of the inspection unit.
d. alloy, shape and condition of the part
d. alloy, shape and condition of the part
- When a magnetic material reaches its curie
temperature the material becomes:
a. magnetic.
b. radioactive.
c. diamagnetic.
d. paramagnetic.
d. paramagnetic.
- Magnetic particle inspection methods on
ferromagnetic materials are recognized as
superior to liquid penetrant techniques when:
a. the surface is plated.
b. the parts are painted.
c. the surface is anodized.
d. dry particles are used for fine surface cracks.
b. the parts are painted.
- A paramagnetic material:
a. is highly magnetic.
b. is slightly magnetic.
c. has no magnetic properties at all.
d. has a demonstrated lack of electron mobility.
b. is slightly magnetic.
- Which of the following will reduce a magnetic
field?
a. Move the direct current coil closer to the part.
b. Reduce the current in only one direction.
c. Move the alternating current coil further away
from the part.
d. Move the part toward the inner surface of the
coil
c. Move the alternating current coil further away
from the part.
- When an external magnetizing force is removed,
some of the magnetic domains remain
preferentially oriented. The additional force
required to return them to their original random
orientation is commonly referred to as:
a. coercive force.
b. applied field force.
c. residual field force.
d. direct current electric force.
a. coercive force.
- When a cylinder is magnetized by a central
conductor, the field is most intense:
a. at the ends of the cylinder.
b. at the outer surface of the cylinder.
c. at the inside surface of the cylinder.
d. halfway through the thickness of the cylinder
wall.
c. 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.
b. Just after the magnetizing current is shut off.
c. When the magnetic particle powder is applied.
d. Just prior to current reversal when using
alternating current.
a. While the magnetizing current is applied.
- Which of the demagnetization methods listed
below is most effective?
a. full-wave rectified
b. half-wave rectified alternating current
c. direct current with reversing and step-down control
d. variable voltage alternating current with
step-down control
c. direct current with reversing and step-down control
- When using the longitudinal magnetization
method to inspect a bar 152 mm (6 in.) long and
5 1 mm (2 in.) in diameter with a 5-turn coil,
which of the following amperage values should
be used?
a. 1200A
b. 3000A
c. 12000A
d. 2000 amp-turns
b. 3000A
- To examine a part 127 mm (5 in.) long and 51
mm (2 in.) in diameter using a 5-turn coil and
head stock magnetic particle machine, what
amperage should be used for longitudinal
magnetization?
a. 3000A
b. 3600A
c. 4500 A
d. 10 000 ampere-turns
b. 3600A
- To examine a bar 381 mm (15 in.) long and
5 1 mm (2 in). in diameter using a 7-turn coil and
head-stock magnetic particle machine, what
amperage should be used for circular
magnetization?
a. 750 A
b. 1800A
c. 1800 amp-turns
d. 49 000 amp-turns
b. 1800A
- If the same amperage is passed through a 25 mm
and 51 mm (I in. and a 2 in.) diameter bar of the
same length and material, the strength of the
magnetic field at the surface:
a. will be the same for both bars.
b. of the 25 mm (1 in.) bar will be one-half that
of the 51 mm (2 in.) bar.
c. of the 25 mm (I in.) bar will be approximately
twice that of the 51 mm (2 in.) bar
d. of the 51 mm (2 in.) bar will be approximately
four times that of the 25 mm (1 in.) bar.
c. of the 25 mm (I in.) bar will be approximately
twice that of the 51 mm (2 in.) bar
- If the same amperage is passed through a 25 mm
(1 in.) diameter bar and a 51 mm (2 in.) diameter
bar of the same length and material, the strength
of the magnetic field at the center of:
a. both bars will be 0.
b. the 25 mm (1 in.) bar will be one-half that of
the 5 1 mm (2 in.) bar.
c. the 51 mm (2 in.) bar will be one-half that of
the 25 mm (1 in.) bar.
d. the 25 mm (1 in.) bar will be approximately
one-fourth that of the 51 mm (2 in.) bar.
a. both bars will be 0.
- When a magnetic field is induced in a part with
prods spaced 152 mm (6 in.) apart, the field is a:
a. circular field.
h. residual field.
c. solenoid field.
d. longitudinal field.
a. circular field.
- When circular magnetization is used to detect subsurface discontinuities, direct current is used
instead of alternating current because:
a. particle mobility is no longer a factor.
b. there is no logical reason to use direct current
instead of alternating current.
c. direct current saturates the magnetic particles
better than alternating current.
d. the skin effect of alternating current reduces
the maximum depth at which discontinuities
can be found.
d. the skin effect of alternating current reduces
the maximum depth at which discontinuities
can be found.
- An inspection method in which an initial magnetizing force is applied to a part and then reduced to a lower continuous value is called:
a. the surge method.
b. the residual method.
c. the multivector method.
d. the continuous method.
a. the surge method.