50 Question MT quiz

1. If 25mm and 50mm diameter bars were magnetised by passing the same current through them, the magnetic fields would be:

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

3. Which of the following is not an acceptable technique for removing a thin film of oil or grease prior to magnetic particle testing?

4. Which of the following casting defects is caused by non-uniform cooling resulting in stresses which rupture the surface of the metal?

5. The length of a part being magnetised by passing an electric current from one end to the other:

6. An electromagnetic yoke produces:

7. Indications at the root of a notch caused by flux leakage resulting from the notch configuration are called:

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

9. A specimen may be demagnetized by which of the following methods?

10. What type of magnetisation used the formula: Ampere-turns=45,000(L/D)?

11. The most common failure mechanism associated with sharp fillets, notches, undercuts and seams is:

12. To detect a lack of root fusion with the magnetic particle method, it must be oriented approximately:-

13. If a current of the same amperage is passed through two conductors of the same dimensions, one of which is magnetic and one of which is non-magnetic, the magnetic field surrounding the conductors will:

14. The deeper a sub-surface discontinuity lies below the surface:-

15. The magnetic particle test technique in which the indicating medium is applied after ceasing application of the magnetising force is called the:-

16. The parts are blanks cut from rolled iron bar stock. They have been rough machined. Inspection by the continuous method, using a circular short, reveals well-defined but broken lines running parallel with the axis on some of the pieces and non indication on others. The broken lines range in length from 6mm to 25mm. These indications are indicative of:

17. A gear with case-hardened ground teeth and hub ends is MT tested. Indications are detected on five of the teeth. Although the indications are very sharp and distinct, they do not break over the edges of the parts. What is the probable identity of the indication?

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

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

20. A coil around the part produces:

21. When testing a bar with an L/D ratio of four in a ten-turn coil, the required current would be:

22. Retentivity refers to a materials ability to retain a certain amount:

23. Comparing parts that have been circularly magnetised and those which have been longitudinally magnetised, which retains the most objectionable residual field if not demagnetised?

24. Residual magnetism may be beneficial as an aid:

25. The end of a magnet at which the lines of flux are thought of as entering the bar is:

26. Which of the following is not a discontinuity common to rolled products?

27. If wet magnetic particle suspension is not uniform, then:

28. A rough forging that has received no further processing is MT tested. A very sharp indication is observed to run every direction, extending deeply into the part and perpendicular to the surface. What is the identity of the indication?

29. To detect lengthwise defects on the inside diameter of hollow parts, you should:

30. Half wave rectified AC (HWDC) is the best current to use for detection of:

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

32. What wattage is most commonly used for mercury vapour bulbs for portable fluorescent magnetic particle inspection?

33. When using the wet method, why should a high velocity flow of wet method bath over surfaces following removal of the magnetizing current not be used?

34. The interpretation of magnetic particle indications may be aided by:

35. Permeability is defined by the formula:

36. The lines of force that form a path round a crack in a ring magnet are called:

37. The pattern of iron powder sprinkled on a paper placed over a bar magnet is called a:

38. Which type of black light source is most suitable for inspection when fluorescent magnetic particle inspection is to be carried out?

39. Cold working indications will not reappear if the part is:

40. Discontinuities in plate, sheet, or strip caused by pipe, inclusions, or blowholes in the original ingot which after rolling are usually flat and parallel to the outside surface are called:

41. Direct current, or three-phase full wave rectified current magnetisation are the most suitable wave forms to use:-

42. A circular field may be included by which of the following methods?

43. A rough forging discontinuity has following characteristics: it occurs on the surface or internally; it is associated with processing at too low a temperature; it is often caused by excessive working; and it creates irregular cavities varying in size. How would it be identified or classified?

44. In longitudinal magnetization the proper term for calculating magnetizating force is:

45. The most effective MT method for inspection of a large casting is using:

46. The strongest magnetic field in a coil is at the:

47. Why is it preferable to disassembly parts before magnetic particle inspection?

48. The proper number of ampere-turns for a given test specimen is determined by:

49. Residual magnetic fields may be used when:

50. When testing for fine surface cracks, the preferred MT method should be:

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