50 Question MT quiz

1. Materials which are weakly attracted magnetically are classified as:

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

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

4. In magnetic particle inspection, it is best to:

5. 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:

6. 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:

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

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

9. A desirable property of magnetic particles used for the inspection medium for either the dry or wet method is that they:

10. Residual magnetic fields may be used when:

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

12. Internal splines and holes drilled parallel to and near test surfaces will cause:

13. Residual magnetism may be beneficial as an aid:

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

15. Determine the L/D ratio for a component 15cm long and 2.5cm diameter.

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

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

18. 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:

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

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

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

22. What equipment is used to determine if a part has been demagnetized?

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

24. 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?

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

26. An electromagnetic yoke produces:

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

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

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

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

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

32. 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?

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

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

35. An interruption in the normal physical structure or configuration of a part which produces an MT indication is called:

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

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

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

39. A coil around the part produces:

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

41. What is the minimum temperature a steel containing 0.8%C has to be heated to before quench cracking can occur?

42. 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?

43. A limitation of low fill factor coil magnetisation techniques is that:

44. 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?

45. Which of the following materials would be UNSUITABLE for magnetic particle inspection?

46. Permeability is defined by the formula:

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

48. The ability of matter to attract other matter to itself is a phenomenon associated with:

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

50. 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:

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