MT LEVEL III  기출 문제 정리

1-1. 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. a random position and may become aligned to attract a magnetic material

d. the same direction as the metal's grain structure

1-2. Permanent magnets의 일반적인 성질

① Normarally, bar magnets have two poles

2-1. 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 fluorescent lighting is used for inspection

d. when the parts being inspected are to be field welded

2-2. wet 자분과 비교해서 dry 자분의 특성

→ permeadility가 크다.

3-1. Gas, misruns. cold laps, and sand inclusions are examples of defects resulting from which of the following Processes?

a. forging

b. grinding

c. castings

d. heat treatment

3-2. 용접부의 toe 부분에서 희미하고 넓은 지시가 전부위에 걸쳐 나타났다.

관련된 지시는?

① crack

② permealiaty difference of HAZ

③ undercut

④ 모재와 용접부의 기하학적 차이

3-3. Round - Shape Indication

→ Porosity

3-4. Which of the Following Casting Defects is Caused by Non-uniform Cooling Kesulting      in Stresses Which Rupture the Surface of the Metal?

→ Hot Tears

4-1. All of the following are valid reasons for the demagnetization of parts after magnetic particle testing except that:

a. magnetism will affect the temperature gauge1 used in subsequent heat treatment

b. residual magnetism may interfere with later machining operations by attracting chips to the part

c. residual magnetism may interfere with later magnetic particle inspection of the part, particularly if a lower magnetizing current or a reverse field will be used

d. residual magnetism may interfere with the removal of the magnetic particles during the cleaning process following inspection

4-2 All Of the following are valid reasons for the demagnetization of parts after magnetic particle testing except that:

a. if the part is to be radiography after magnetic particle inspection. residual magnetism may interfere with the electro magnetic radiation spectrum

b. residual magnetism may attract chips or small particles in service, causing galling or mechanical wear

c. residual magnetism cou1d interfere with the operation or accuracy of instruments placed on or near the part during service

d. residual magnetism can disturb the welding arc path on parts to be welded

4-3. demagnetized mathod of coil에서 시편의 위치는 ?  in the coil

6. Subjecting a part to a magnetic field that is constantly reversing in polarity and gradually diminishing in strength accomplishes which of the following?

a. the part becomes magnetized

b. the part becomes demagnetized

c. the strength of the retained magnetic field increases

d. deep-lying defects are located

7. 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. permitting the solids to settle out of suspension

d. measuring the pull on a magnet

8. An important factor that must be considered when selecting a method of magnetization is  :

a. the location of inspection station

b. the alloy, shape, and condition of the part

c. the permeability of the part

d. both b and c

9. An important factor that must be considered when selecting a method of magnetization is:

a. the type of magnetizing current

b. the availability  of handling equipment

c. the material's Curie point

d. both a and b

10 What happens to a magnetic material when it reaches its curie temperature?

a. it becomes paramagnetic

b. it becomes diamagnetic

c. it becomes nonmagnetic

d. it becomes radioactive

11. A material that is repelled by magnetism is:

a. diamagnetic

b. ferromagnetic

c. paramagnetic

d. overtly magnetic

12. Materials weakly attracted by magnetic fields are:

a. paramagnetic

b. dual magnetic

c. covertly magnetic

d. diamagnetic

12. Paramagnetic 보다 작은 자장을 나타내는 것은?

→ Diamaynetic

13. What magnetic property does a paramagnetic material possess?

a. is highly magnetic

b. has no magnetic property at all

c. is slightly magnetic

d. has a demonstrated lack of electron mobility

14. Methods used to preserve powder patterns include:

a. photographs

b. transparent tape

c. transparent lacquer

d. all of the above

15. Magnetic particle inspection methods are recognized as superior to liquid penetrant techniques when:

a. corroded surfaces are inspected

b. surfaces are anodized

c. parts are painted

d. both a and c

16. In what way can a magnetic field be reduced?

a. reduce the current

b. move the part further away from the coil

c. move the coil further away from the part

d. all of the above

17. When the external magnetizing force has been 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. DC electric current force

b. coercive force

c. residual field force

d. applied field force

18. When a cylinder is being magnetized a central conductor, the field is most intense :

a. at the outer surface of the cylinder

b. halfway through the thickness of the cylinder wall

c. at the ends of the cylinder

d. at the inside surface of the cylinder

19. When Is the magnetic field strongest in an object being inspected by the magnetic particle method?

a. Just prior to current reversal when using AC current

b. Just after the magnetizing current Is shut off

c. while the magnetizing current Is applied

d. when the magnetic particle powder Is applied

19-1. 실린더의 외경, 단면적 고려하여 일반적으로 검사시에는?

→소요전류가 낮은 부위부터

20. Which of the demagnetization methods listed below ismost effective?

a. DC with reversing and step-down control

b. variable voltage AC with step-down control

c. half-wave rectified AC

d. full-wave rectified

20-1. 탈자가 필요한 경우

→ 차후 공정에 영향을 주는 경우

20-2. 탈자가 이루어졌는지 확인하는 방법 →④ All of the above

→ 자석이용

→ 자분이용

20-3. 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

b. North-South

c. irrelebant(no difference)

d. South-West

21-1. When using the longitudinal magnetization method to inspect bar 152 mm (6 in) long and 51mm (2 in) diameter with a 5-turn coil. which of the following amperage values should be used? (NI =[eqn: {45000 } over {L/D }])

a. 1200 amps

b. 3000 amps

c. 2000 amp-turns

d. 12000 amp-turns

21-2. 길이가 18in이고 직경이 1.5in, 자화전류가 3000Amp일 때 L/D비는? 12

21-3. In Magnetizing a 1.5 inch Outside Diameter Tube with a 0.125 inch Wall Thickness Using Direct Conduction and Direct Current of 1500 Amps, What is the Field Strength of the Internal Diameter?(for Non-Magnetic)

→Zero

21-4. To examine a part 127 mm (5 in) long and 51 mm (2 in) diameter using a 5-turn coil and head-stock magnetic particle machine, what amperage should be used for longitudinal magentization?

a. 3000 amps

b. 3600 amps

c. 4500 amps

d. 10000 amps-turns

22-1. To examine a bar 38cm (15 in) long and 51 mm (2 in) in diameter using a 7-turn coil and head-stock magnetic particle machine, what amperage will be used for circular magnetization?

a. 750 amps

b. 1800 amps

c. 1800 amp-turns

d. 49000 amp-turns

22-2. 원형자회시 전류를 계산할 때 고려하는 Factor는 ?

→ 직경

23-1. If the same amperage is passed through a 25mm (i in) and a 51 mm (2 in) diameter bar of the same length, which of the following statements is most applicable relevant to the magnetize field at the surface of the bars?

a. the strength of the magnetic field at the surfaces will be the same for both bars

b. the strength of the magnetic field at the surface of the 25 mm 1 in) bar will be approximately twice that of the 51 mm (2 in) bar

c. the strength of the magnetic field at the surface of the 51 mm (2 in) bar will be approximately four times that of the 25 mm (1 in) bar

d, the strength of the magnetic field at the surface of the 25 mm (1 in) bar will be one-half that of the 51 mm (2 in) bar

23-2. If the same amperage is passed through a 25 mm (i in) diameter bar and a 51m (2 in) 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?

a. the strength of the magnetic field inthe center of the 25mm (i in) bar will be one-half that of the 51 mm (2 in) bar

b. the strength of the magnetic field at the encter of the 51 mm(2in) bar will be one-half as that of the 25 mm (1 in) bar

c. the strength of the magnetic field in the center of both bars will be zero

d. the strength of the magnetic field in the center of the 25 mm (1 in) bar will be approximately one-fourth the value for the 2-inch bar

23-3. A low fill factor results when the ratio of the cross-sectional area of the part to the coil is :

a. greater than or equal to 1/2

b. greater than 2

c. less than 1/10

d. one

23-4. A 7-turn coil at 1000 amps is used to inspect a round solid part 38cm (15 in) long and 64 mm (2-1/2 in) in diameter. What is the L/D ratio?

a. 2.14

b. 6

c. 7500 amp-turns

d. 45000 amp-turns

24-1. To examine a bar 38cm (15 in) long and 51 mm (2 in) in diameter using a 7-turn coil and head-stock magnetic particle machine, what amperage will be used for circular magnetization?

a. 750 amps

b. 1800 amps

c. 1800 amp-turns

d. 49000 amp-turns

24-2. 축통전법에서 가장 자장이 걸리는 부분은?

incide Dia of pipe

24-3. 축통전법에서 Non-magnetic central conductor 내에서의 자장분포는?

liely change

24-4. When circular magnetization is used and it is important to detect subsurface defects, direct current is used instead of alternating current because.

a. particle mobility is no longer a factor

b. DC saturates the magnetic particle better than AC

c. the skin effect of AC reduces the maximum depth at which defects can be found

d. there is no logical reason to use DC instead of AC

25-1. When a magnetic field is induced in a part with prods spaced 152 mm (6 in) apart, the field is a:

a. solenoid field

b. longitudinal field

c. distorted circular field

d. residual field

25-2. Prod 검사기법에서 Arc 방지 기법

→ All of the above

26. When circular magnetization is used and it is important to detect subsurface defects, direct current is used instead of alternating current because.

a. particle mobility is no longer a factor

b. DC saturates the magnetic particle better than AC

c. the skin effect of AC reduces the maximum depth at which defects can be found

d. there is no logical reason to use DC instead of AC

27. 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:

a. residual method

b. multivector method

c. continuous method

d. surge method

28. When deciding to inspect a part by the residual method, the strength of the residual field in the part should be considered. Factors that affect this field include:

a. the strength of the magnetizing force

b. the retentivity of the test part

c. the material alloy

d. all of the above

29. Factors that must be considered when interpreting an indication are:

a. the direction of the magnetic field

b. the strength of the leakange field at the indication

c. the orientation and shape of the indication

d. all of the above

33. 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?

a. circular magnetization

b. longitudinal magnetization

c. either a or b

d. neither a nor b

34. When using DC, an indication is detected. What is the next logical step to determine if the indication results from a surface of subsurface condition?

a. reinspect using the surge method

b. demagnetize and apply powder

c. reinspect at higher amperage

d. reinspect using AC

35. Which of the statements made below is most appropriate concerning materials I and II represented by the hysteresis curves shown in Figure I?

a. material I is not a good subject for magnetic particle inspection

b. material I could be used for dry powder magnetic particles

c. material II could be used for dry powder magnetic particles

d. material II is paramagnetic

36-1. The curve shown in Figure I for material is indicates that it:

a. has a high coercive force

b. has a high retentivity

c. has a high permeability

d. would make an excellent permanent magnet

36-2. Magnetic Particle을 검사할수 있는 구간은 ?  a-b

36-3. Coerce force을 나타내는 점 ? c

36-4. Saturated point는? a

36-5. 가장 강하게 자화되는 구간은? 0～a 구간의 가장 큰 기울기

37. Point B on the hysteresis curve for material I shown in Figure I:

a. repersents the mid=point of the rectified Ac current applied

b. is the material's magnetic saturation point

c. reperscents the  point at which the residual magnetic value will remain when the magnerizing current is removed

d. is the limit of coercibe force

38. Which point on the hysteresis curve shown in Figure I represents the residual field value?

a. A

b. D

c. C

d. E

39. Which 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. alternating current

b. direct current

c. half-wave rectified alternating current

d. full-wave rectified current

40. An important factor that should be considered when selecting a method of magnetization is:

a. field strength value

b. available equipment

c. configuration of the part

d. all of the above

41. Which of the following discontinuities occur as a result of the rollong process?

a. blowholes and pipe

b. laminations

c. fissures

d. all of the above

42. Which of the following discontinuities occur as a result of the forging process?

a. pipe

b. laps

c. lminations

d. all of the above

43. If an indication is formed when using the residual method as well as the continous method, it is most likely:

a. very deep and tight

b. very shallow and open to the surface

c. a relevant indication

d. a nonrelevant indication

44. Plated parts can be reliably tested using the magnetic particle method if the plating is less than:

a. 0.1mm (0.004 in) thick

b. 0.2mm (0.008 in) thick

c. 0.8mm (0.03 in) thick

d. 1mm (0.04 in) thick

45. The magnetic lines of flus r flux in a permanent magnet:

a. flow from the morth pole through the magnet to the south pole

b. change direction 60 times a second with the magnetizing current

c. enter the south pole and leave the north pole

d. in all cases produce a longitudinal field

46. Which of the following magnetization techniques should be avoided when performing magnetic particle testing ?

a. longitudinal magnetization

b. circular magnetization

c. vector magnetization

d. parallel magnetization

47. Banding is a common term used to describe:

a. field strength relative to the poles of a permanent magnet

b. a method of mounting cylindrical objects on a bench system

c. the appearance of powder patterns at laminations found in heavy

d. powder patterns created by using excess amperage

48. When attempting to demagnetize a part containing a circular residual field:

a. consideration of the material's hysteresis is most important

b. establish a longitudinal field and then proceed with demagnetization

c. use half-wave current with a bead shot setup and step-down magnetization to assure complete removal of the residual field

d. use a swinging cyclic field

49.  The input current requirements for MT equipment depend in part upon the:

a. duty cycle required

b. shop electrical service

c. prod spacing required on average production part types

d. size of current cables

50. Small part requiring demagnetization should be :

a. loaded in baskets and passed through an AC coil

b. demagnetized after assembly to assure complete demagnetization of the entrre assembly

c. processed through a demagnetization cycle one at a time

d. loaded in a steel basket for better field distribution

51-1. The best shape for magnetic particle used in the dry powder method  is:

a. flat

b. globular

c. long and slender

d. a mixture of b and c

51-2. Slender와 Globulan 자분의 차이 ?

→ Slender Type이 더 자화가 잘 된다.

52. 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:

a. residual method

b. multivector method

c. continuous method

d. surge method

53. When deciding to inspect a part by the residual method, the strength of the residual field in the part should be considered. Factors that affect this field include:

a. the strength of the magnetizing force

b. the retentivity of the test part

c. the material alloy

d. all of the above

54. Factors that must be considered when interpreting an indication are:

a. the direction of the magnetic field

b. the strength of the leakange field at the indication

c. the orientation and shape of the indication

d. all of the above

55. 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

b. North-South

c. irrelevant(no difference)

d. South-West

56. When using DC, an indication is detected. What is the next logical step to determine if the indication results from a surface of subsurface condition?

a. reinspect using the surge method

b. demagnetize and apply powder

c. reinspect at higher amperage

d. reinspect using AC

57. Which 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. alternating current

b. direct current

c. half-wave rectified alternating current

d. full-wave rectified current

57. An important factor that should be considered when selecting a method of magnetization is:

a. field strength value

b. available equipment

c. configuration of the part

d. all of the above

58. Which of the following discontinuities occur as a result of the rollong process?

a. blowholes and pipe

b. laminations

c. fissures

d. all of the above

59. Which of the following discontinuities occur as a result of the forging process?

a. pipe

b. laps

c. lminations

d. all of the above

60. If an indication is formed when using the residual method as well as the continous method, it is most likely:

a. very deep and tight

b. very shallow and open to the surface

c. a relevant indication

d. a nonrelevant indication

61. Plated parts can be reliably tested using the magnetic particle method if the plating is less than:

a. 0.1mm (0.004 in) thick

b. 0.2mm (0.008 in) thick

c. 0.8mm (0.03 in) thick

d. 1mm (0.04 in) thick

62. The magnetic lines of flus or flux in a permanent magnet:

a. flow from the morth pole through the magnet to the south pole

b. change direction 60 times a second with the magnetizing current

c. enter the south pole and leave the north pole

d. in all cases produce a longitudinal field

63. Which of the following magnetization techniques should be avoided when performing magnetic particle testing ?

a. longitudinal magnetization

b. circular magnetization

c. vector magnetization

d. parallel magnetization

64. Banding is a common term used to describe:

a. field strength relative to the poles of a permanent magnet

b. a method of mounting cylindrical objects on a bench system

c. the appearance of powder patterns at laminations found in heavy

d. powder patterns created by using excess amperage

65. When attempting to demagnetize a part containing a circular residual field:

a. consideration of the material's hysteresis is most important

b. establish a longitudinal field and then proceed with demagnetization

c. use half-wave current with a bead shot setup and step-down magnetization to assure complete removal of the residual field

d. use a swinging cyclic field

66.  The input current requirements for MT equipment depend in part upon the:

a. duty cycle required

b. shop electrical service

c. prod spacing required on average production part types

d. size of current cables

67. Small part requiring demagnetization should be :

a. loaded in baskets and passed through an AC coil

b. demagnetized after assembly to assure complete demagnetization of the entrre assembly

c. processed through a demagnetization cycle one at a time

d. loaded in a steel basket for better field distribution

68. which of the following method of particle application must be employed when performing multidirectional magnetism ?

a. wet method

b. dry method

c. continuous method

d. residual method

69. magnetic rubber의 내용중 맞는 것은?

magnetic rabber의 advantage

① reveal finer crack

② examined under the best conditions

③ optics if necessary

④ surface contour and roughness of the inspected curea

⑤ surface replica of the surface condition

⑥ permanet record

70. Settling Test로 검사할 수 없는 것은?

→ Excess current Density

71. 자분의 농도를 알 수 있는 방법은?

→Settling Test

72. Circulars magnetized componental magnetic flux?

④ Within in material

73. S.I 자속밀도의 단위 : Telsa

74. Materialei peameability을 나타내는 point는 ? 해당사항없음

75. The flux density at the magnetism induced by a coil can be controlled by varying

A. the coil size

B. the curont in the coil

C. the number of turns in the coil

D. all of the above

76. Residual manguetizion 적용은

→ Hight carbon steel

77. 가장 유효한 MT 방법은?

→ 전류가 흐르는 동안에 자분적용

78. Continious Magnetitafion 에서의 자분적용시기는?

→ 전류가 흐르는 동안

79. Field indication를 적용할 수 있는 자화방법은? ⑤

① lomgitudinal magnetization

② head shot

③ circularly mangnetization

④ none of the above

⑤ all of the above

80. The sensitivity of magnetic particle testing is greatest when the discontinuity      is

→ perpendicular to the direction of the magnetic flux

81. 가장 효과적인 Dedemagnetization은 ?

→ DC를 이용하여 점차 감소

82. Magnetic Writing 문제

83. Eletrod Beam 용접의 장점 → 열영향부위가 작다.

84. Deep-lying 결함검출시 사용하는 전류

→HWDC

85. The Auumulation of Portides al a Site on the Part Surface, Collected at and Held to the Site by the magnetic Leakage Field, is Called-an Indication.

86. Which residual field is most difficult to demagnetize?

a. longitudinal   b. circular   c. vector    d, binodal

87. Why are large soft contact areas such as lead or copper braid used for surfaces or headstocks?

a. to increase the contact area and reduce the possibility of burnning the part

b. because of their low melting points

c. because they help heat metal, thus facilitating magnetic induction

d. to increase the contact area and flux density

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

a. retest at a higher amperage

b. demagnetize

c. retest at lower amperage

d. both a and b

89. Which of the following casting defects is caused by nonuinform cooling resulting in stresses which rupture the surface of the metal?

a. shrink

b. hot tears

c. porosity

d. dross

90. When adding concentrate on any wet magnetic particle suspension liquid, it is common practice to :

a. add powder directly to the suspension liquid

b. make a small, slurry-like test mixture of the powder

c. do both of the above

d. do neither of the above

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

a. a discontinuity

b. a defect

c. an indication

d. magnetic writing

92. When the most complete demagnetization available is desired and demagnetization is to be accomplished by placing the part in a coil energized with AC of progressively decreasing amperage, the following orientation of long axis of the part is most desirable:

a. East-West

b. North-South

c. South-West

d. North-East

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

a. oestered   b. ohm   c, gauss   d, ampere

94. Subjecting a part to a magnetic field that is constantly reversing in polarity and gradually diminishing in strength accomplishes which of the following ?

a. the part becomes magnetized

b. the part becomes demagnetized

c. the strength of the retained magnetic field increases

d. deep-lying defects are located

95. When the external magnetizing force has been 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. DC electric current force

b. coercive force

c. residual field force

d. applied field force

96. Which of the demagnetization methods listed below is most effective?

a. DC with reversing and step-down control

b. Variable voltage AC with step-down control

c. half-wave rectified AC

d. full-wave rectified

97. Factors that must be considered when interpreting an indication are :

a. the direction of the magnetic field

b. the strength of the leakage field at the indication

c. the orientation and shape of the indication

d. all of the above

98. 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 ?

a. reinspect using the surge method

b. demagnetize and apply powder

c. reinspect at higher amperage

d. reinspect using AC

99. Banding is a common term used to describe :

a. field strength relative to the poles of a permanent magnet

b. a method of mounting cylindrical objects on a bench system

c. the appearance of powder patterns at laminations found in heavy plate material

d. powder patterns created by using excess amperage