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Magnetic Testing Level II > Theory > Flashcards

Theory Flashcards

0
Q

Residual magnetism may be beneficial as an aid:

A. In demagnetization.
B. in proper heat treating.
C. In deposition of weld metal.
D. In interpretation and evaluation of indications.

A

D. In interpretation and evaluation of indications.

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1
Q

The interpretation of magnetic particle indications may be aided by:

A. Observing with a magnifying glass.
B. reproducing the indication after demagnetizations.
C. Observing the indications after the part is pre-cleaned.
D. Observing the indications after the part is post-cleaned.

A

A. Observing with a magnifying glass.

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2
Q

An interruption in the normal physical structure or configuration of a part which produces a magnetic particle testing indication is called:

A. A defect.
B. an indication
C. A deformation.
D. A discontinuity.

A

D. A discontinuity

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3
Q

Comparing parts that have been circularly magnetized and those that have been longitudinally magnetized, which retain the most objectionable residual field if NOT demagnetized?

A. Circular
B. vectored
C. Remnant
D. Longitudinal

A

D. Longitudinal

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4
Q

What type of magnetization uses the formula: Ampere turns = 45,000/(L/D)?

A. Circular
B. parallel
C. vectored
D. Longitudinal

A

D. Longitudinal

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5
Q

Why are soft contact pads such as lead or copper braid used for surfaces and head stocks?

A. To increase the contact area and reduce the possibility of burning the part.
B. because they help heat metal, thus facilitating magnetic induction.
C. To increase the contact area flux density.
D. Because of their low melting point.

A

A. To increase the contact area and reduce the possibility of burning the part.

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6
Q

A rough forging that has received no further processing is magnetic particle tested. An indication is observed to run in every direction and appear to extend deeply into the part and perpendicular to the surface. It is very sharp. What is the probable indentity of the indication?

A. Forging burst
B. flake
C. Seam
D. Lap

A

A. Forging burst

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7
Q

A gear with case-hardened ground teeth and hub ends is magnetic particle tested. Individual indications are detected on a five teeth and one end surface of the hub. The indications do not break over the part edges. What is the probable identity of the indication?

A. Grinding cracks
B. quench cracks
C. Inclusions
D. Porosity

A

A. Grinding cracks

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8
Q

If an overall pattern (sometimes circular lines) appears on the test surfaces, how should the inspector reprocess the test piece?

a. Demagnetize the piece
b. Retest at a higher amperage
c. Retest at a lower amperage
d. Part is not testable

A

c. Retest at a lower amperage

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9
Q

A prime consideration when selecting a powder to be used as a magnetic particle medium is to select a powder that:

a. will adhere to the surface being tested.
b. provides a low contrast to the surface being tested.
c. provides a high contrast to the surface being tested.
d. requires a high demagnetization current to remove it.

A

c. provides a high contrast to the surface being tested.

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10
Q

When testing for fine shallow surface cracks, the preferred magnetic particle test method should be:

a. dry alternating current
b. dry direct current
c. wet alternating current
d. wet direct current

A

c. wet alternating current

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11
Q

Which of the following is an advantage of the dry method over the wet method?

a. It is more sensitive to fine surface cracks.
b. It is easier to use the field inspection with portable equipment.
c. It is faster then the wet method when testing a number of small parts.
d. It is more capable of providing full service coverage on irregularly shaped parts.

A

b. It is easier to use the field inspection with portable equipment.

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12
Q

When testing a bar with a length-to-diameter ration of 4 in. in a 10 turn coil, required current would be:

a. 45,000 A.
b. 18,000 A.
c. 1125 A.
d. Unknown, more information is needed.

A

c. 1125 A.

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13
Q

Internal splines and holes drilled parallel to, or near, test surfaces will cause:

a. sharp, well defined indications directly aligned with the part’s internal contours.
b. broad, fuzzy indications directly aligned with the internal contours.
c. distinct indications not aligned with the part’s internal contours.
d. no indications.

A

b. broad, fuzzy indications directly aligned with the internal contours.

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14
Q

A limitation of magnetization techniques is that:

a. regardless of part size, the part cannot be painted.
b. the coil must be of maximum diameter in relation to the part.
c. the effective field is generally limited on either side of the coil.
d. small diameter parts must be placed close to the center of the coil.

A

c. the effective field is generally limited on either side of the coil.

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15
Q

The term used to refer to the total opposition to flow of current represented by the combined effect of resistance, inductance, and capacitance of a circuit is:

a. inductive reactance
b. impedance
c. reluctance
d. decay

A

a. inductive reactance

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16
Q

A 3500 ampere-turn coil shot is required to be performed in a 5-turn coil after a head shot of 800 A using the wet continuous method. In order to properly conduct the coil shot it is necessary to:

a. demagnetize the part between the head and first coil shot.
b. check the part for residual magnetism with a field indicator.
c. remove all residual wet magnetic particle field from the part using clean, dry absorbent rags.
d. place the part in the coil and continue the inspection after evaluating the head shot indications.

A

d. place the part in the coil and continue the inspection after evaluating the head shot indications.

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17
Q

A desirable property of magnetic particles used for either dry or wet method is the they:

a. be toxic.
b. be non-ferromagnetic
c. possess high retentivity
d. possess high permeability

A

d. possess high permeability

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18
Q

External poles which are too strong to permit good inspection of a part are more likely to result when using:

a. longitudinal magnetization
b. polarized magnetization
c. residual magnetization
d. circular magnetization

A

a. longitudinal magnetization

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19
Q

The accumulation of particles at a site on the surface, collected at and held to the site by magnetic leakage field, is called:

a. a defect
b. an indication
c. a discontinuity
d. magnetic writing

A

b. an indication

20
Q

Where particles are attracted to a site on the surface of a part by magnetic leakage field that is caused by a condition such as a crack, lap, or condition not acceptable to the applicable standards for the part, then we have:

a. a defect
b. an indication
c. discontinuity
d. a non-relevant indication

A

a. a defect

21
Q

Which of the following is an acceptable technique for removing a thin film of oil or grease prior to magnetic particle testing?

a. wash with a solvent
b. degrease using a a sand-blasting method
c. Brush the surface with power wire brush
d. coat the surface with a thick layer of chalk and then wipe with cloth.

A

a. wash with a solvent

22
Q

Which of the following is the most common method used for preserving and documenting magnetic particle indications?

a. photography
b. color-tinted tape
c. color-tinted lacquer
d. a concise word description

A

d. a concise word description

23
Q

Which of the following is a discontinuity commonly associated with the welding process?

a. flakes
b. seams
c. laminations
d. lack of penetration

A

d. lack of penetration

24
Q

Of the following discontinuity categories, which one is considered most detrimental of service life of an item?

a. corrosion
b. subsurface inclusions
c. cracks open to the surface
d. subsurface porosity and voids

A

c. cracks open to the surface

25
Q

If 25 mm (1 in.) and 51 mm (2 in.) in diameter bars of the same material were magnetized by passing the same current through them, the magnetic fields would be:

a. same for both
b. stronger in the 51 mm (2 in.) diameter bar
c. weaker in the 25 mm (1 in.) diameter bar
d. stronger in the 25 mm (1 in.) diameter bar

A

d. stronger in the 25 mm (1 in.) diameter bar

26
Q

The most effective magnetic particle test method for inspection of a large casting is using:

a. a central conductor
b. direct magnetization
c. multidirectional magnetization
d. prod inspection for two directions

A

c. multidirectional magnetization

27
Q

The most common failure mechanism associated within-service parts with sharp fillets, notches, undercuts and seams is:

a. shrinkage
b. crystallization
c. decarburization
d. fatigue cracking

A

d. fatigue cracking

28
Q

When it is believed that a discontinuity has been removed by a grinding operation, the next operation is to:

a. repair it
b. sign off inspection of the part
c. measure it so see if minimum thickness remains
d. re-examine the area by magnetic particle testing

A

d. re-examine the area by magnetic particle testing

29
Q

During a magnetic particle test, non relevant indications due to residual local poles are noted to be interfering with the magnetic particle testing. For a successful examination one should:

a. use more amperage
b. lower the amperage
c. magnetize in other direction
d. demagnetize the remagnetize in the desired direction

A

d. demagnetize the remagnetize in the desired direction

30
Q

The unit of measure on one line of flux per square centimeter of area is one:

a. ohm
b. gauss
c. ampere
d. oersted

A

b. gauss

31
Q

the ability of matter to attract other matter to itself is a phenomenon associated with:

a. magnetism
b. field strength
c. pole strength
d. coercive strength

A

a. magnetism

32
Q

Materials which are strongly attracted to a magnet are called:

a. polorized
b. magnetized
c. nonmagnetic
d. ferromagnetic

A

d. ferromagnetic

33
Q

The end of the magnet at which the lines of flux are thought of as entering the bars is the:

a. north pole
b. south pole
c. positive pole
d. negative pole

A

b. south pole

34
Q

The general term used to refer to a break in the metallic continuity of the part being tested is:

a. discontinuity
b. crack
c. seam
d. lap

A

a. discontinuity

35
Q

The lines of force that form a path around the crack in a ring magnet are called:

a. leakage flux
b. field strength
c. magnetic lines
d. longitudinal field

A

a. leakage flux

36
Q

Since the magnetic lines of force within a bar magnet run the length of the bar, it is said to be:

a. randomly magnetized
b. circularly magnetized
c. permanently magnetized
d. longitudinally magnetized

A

d. longitudinally magnetized

37
Q

Lines of flux are thought to leave a magnet at the:

a. north pole
b. south pole
c. positive pole
d. negative pole

A

a. north pole

38
Q

A break in the magnetic uniformity of a part that is called a magnetic discontinuity is related to a sudden change in:

a. resistivity
b. inductance
c. permeability
d. capitance

A

c. permeability

39
Q

In order to detect defects in different directions in a material by magnetic particle inspection, it is best to use:

a. only one field
b. other probe locations
c. a high frequency field
d. two or more fields in different directions

A

d. two or more fields in different directions

40
Q

The wattage most commonly used for mercury vapor bulbs for portable florescent magnetic particle inspection is:

a. 50 watts
b. 75 watts
c. 100 watts
d. 200 watts

A

c. 100 watts

41
Q

An example of non relevant indication that would be classed as a magnetic discontinuity rather than an actual discontinuity could be caused by:

a. corrosion
b. a slag pocket
c. grinding cracks
d. a known abrupt change in the hardness of the part

A

d. a known abrupt change in the hardness of the part

42
Q

Subjecting a magnetized object to a magnetic force that is continually reversing its direction and graduallly decreasing in intensity is known as:

A. magnetization
B. continuous method
C. Residual method
D. demagnetization method

A

D. demagnetization method

43
Q

Which of the following induces a longitudinal magnetic field?

a. prod
b. yoke
c. head shot
d. internal conductor

A

b. yoke

44
Q

Which one of the following materials has permeability much greater than of air?

a. permeability material
b. diamagnetic material
c. paramagnetic material
d. ferromagnetic material

A

d. ferromagnetic material

45
Q

Demagnetization would be required if:

a. the material has low retentivity
b. the object is to be electric arc welded
c. the material has reluctance
d. heat treatment is to be carried out

A

b. the object is to be electric arc welded

46
Q

One of the disadvantages of half-wave magnetization is, when demagnetizing:

a. the current has skin effect
b. the current does not reverse
c. the current passes very deep
d. the current passes only on the surface

A

b. the current does not reverse

47
Q

In longitudinal magnetization of a round bar, residual magnetization will be:

a. greatest at the center of bar
b. greatest at the ends of the bar
c. the same all over on the bar
d. the minimum at the ends

A

b. greatest at the ends of the bar

Magnetic Testing Level II (1 decks)

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