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Home , Annealing (metallurgy), Carburizing, Martempering, Muffle furnace

UNIT – 6 HEAT TREATMENT PROCESSES

01. Salt bath of liquid contains ____ a) Sodium cyanide, Sodium carbonate, Benzene chloride b) cyanide, Sodium carbonate, Sodium chloride c) Sodium cyanide, Sodium carbonate, Sodium chloride d) None

02. ______statements is/are false for heat treatment processes. a) process is designed to overcome limitations of b) is obtained as final phase in martempering processes. c) Water is used as quenching medium in Jominy end quench test d) All the above

03. The process which improves machinability of , but lowers the is _____ a) Process b) Normalising c) Full annealing d) Spheroidising

04. Carburising is ______. a) process b) case process c) Annealing process d) None

05. The process of reheating martensitic to reduce its brittleness without any significant loss in its hardness is ______. a) Annealing b) Normalising c) Quenching d) Hardening

06. Insufficient hardness after tempering may be due to ______. a) Tempering too low b) Tempering temperature too high c) Oxidising atmosphere in furnace d) Any of the above

07. Spheroidise annealing used to produce speroidal or globular form of ____ from plates of in steel. a) Cementite b) c) Pearlite d) Ferrite

08. The process of involving the heating of steel above the upper critical temperature and then cooled in furnace is known as ______. a) Annealing b) Normalising c) Tempering d) Hardening

09. A steel is heated at about 875°C where the structure consists of only austenite. It is then cooled suddenly at a temperature of about 250° to 525°. This process of heat treatment is known as a) Annealing b) Normalising c) Martempering d)

10. Application of batch furnaces are ______. a) Tool making b) In Maintenance shop c) Both a & b d) None

11. Semi- is a type of ______. a) Gas fire furnace b) Oil & Gas fire furnace c) Electric fire furnace d) None

12. Surface of a steel component becomes hard due to phase transformation austenite to in _____ a) b) Flame hardening c) Both a & b d) None

13. _____ furnace protects the steel from oxidation. a) Full muffle b) Direct fired c) Oil or gas fired d) Semi muffle

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14. If a sample of steel shows excessive hardness after tempering, the probable cause could be a) Excessive proportion of alloying elements b) Insufficient holding time during tempering c) High temperature during tempering d) Change in volume during cooling

15. _____ property is affected by heat treatment. a) Hardness b) strength c) d) All

16. process is carried out in ______. a) Muffle furnace b) Electric furnace c) Gas furnace d) All

17. _____ heat treatment process is used for medium steel. a) Box annealing b) Process annealing c) Bright annealing d) Full annealing

18. _____ are heat treatment processes. a) Annealing b) Normalising c) Tempering d) All

19. Killed steel is ______. a) Steel which has been shaped on a power hammer b) Steel which is deoxidized in the ladle with & aluminum c) Steel with more than normal percentage of carbon d) Steel that has lost its properties due to excessive alloying

20. Austenitic stainless steel contain & nickel in amounts required to assure that even at room , the retain their crystalline structures which are _____ a) HCP b) cubic c) FCC d) Partly amorphous

21. Flame hardening involves _____ a) heating the surface above the transformation range b) quenching after heating c) minimum case depth 1 mm d) All the above

22. In a hardening process, the hypo eutectoid steel is a) Heated from 30° - 50° above the upper critical temp & then cooled in still air b) Heated from 30° - 50° above the upper critical temp & then cooled slowly in furnace c) Heated from 30° - 50° above the upper critical temp & then cooled suddenly d) Heated below or close to the lower critical temp & then cooled slowly

23. _____ temp range represents the tempering temp for C 30 steel. a) 100° – 150° b) 550° – 660° c) 860° – 890° d) 1400° - 1450°

24. Rapid cooling of austenite results in transformation to a) Pearlite b) Banite c) Martensite d) Ferrite

25. When the steel is normalized, it’s ______. a) point increases b) Ductility decreases c) Ultimate tensile strength increases d) All of these

26. The main objectives of heat treatment is/are ______a) To relieve internal stresses b) To refine grain structure c) To improve machinability d) All

27. Annealing is done _____. a) To harden the surface b) for surface smoothness c) for relieving stresses d) to improve microstructure for good surface finish

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28. ______is the last phase obtained after completing heat treatment cycle in patenting process a) b) Martensite c) Pearlite d) None

29. Advantage of liquid carburizing ______a) salt bath offer rapid & uniform heating b) Low distortion c) Negligible surface distortion d) All

30. Cracks of vertical nature & dark coloured fissures in a sample of indicates that a) steel contains excessive alloying elements b) steel has been burned c) steel has been properly hardened d) hardness accordance with the carbon percentage

31. The temperature range of the solid carburizing in degree celsius ____ a) 750 – 850 b) 721 – 800 c) 925 – 950 d) 550 – 650

32. Soaking time _____ with increase in section thickness and the amount of alloying elements a) decreases b) remains same c) increases d) none

33. In normalizing, one of the following statements is not correct. a) it relieves internal stresses b) it produces a uniform structure c) the rate of cooling is moderately high d) the rate of cooling is slow

34. Solid carburizing is also called as ______. a) Open carburizing b) Hidden carburizing c) Quick C d) Pack C

35. The process of decomposition martensite structure, by heating martensitic steel below its critical temperature is called as _____ a) Austenitizing b) Quenching c) Tempering d) None

36. Annealing of steel is done to impart which one of the following property on steel? a) Hardness b) toughness c) ductility d) brittleness

37. Quenching operation is usually followed by ______. a) Annealing b) Normalising c) Tempering d) None

38. Steel can be hardened quickly by the process of ______. a) b) Cyaniding c) Nitriding d) Carburising

39. The hardness of steel increases if it contains _____. a) Pearlite b) Ferrite c) Cementite d) Martensite

40. Austenite in steel is transformed into “fine pearlite structure” by ______. a) Annealing b) Normalising c) Tempering d) Hardening

41. During heat treatment, the formation of thick layer of scale on the surface of steel articles is mainly due to a) Excessive hardness b) Oxidation c) Reduction d) Coarse grain structure

42. In flame hardening oxy- flame is used. a) True b) False

43. _____ can be used as fuel in . a) Liquid fuels b) coke gas c) producer gas d) any of the above

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44. Induction hardening is basically ______. a) carburizing process b) surface hardening process c) core hardening process d) None of these

45. One of the following is not the purpose of full annealing a) Refine grains b) induces softness c) remove strain and stresses d) produces hardest material

46. _____ furnace is used for steel only. a) Cupola b) Open hearth c) Indirect arc furnace d) All

47. One of the following structure is least hard. a) Pearlite b) Martensite c) Austenite d) Sorbite

48. Case depth of gas carburizing is up to ______a) 0.2-0.5 mm b) 0.4-0.6 mm c) 0.7-0.8 mm d) 0.9-1.0 mm

49. A modified quenching procedure used to minimize distortion & cracking that may develop during uneven cooling the heat treated material is _____ a) Austempering b) Martempering c) Tempering d) All

50. Insufficient hardness after tempering may be due to ______a) Tempering temp too low b) Tempering temp too high c) oxidizing atmosphere in the furnace d) any of the above

51. Full muffle type furnaces protect the steel from oxidation by ____ a) circulating the gases around the chamber containing steel b) circulating the gases in the chamber containing steel c) Both a & b d) None of these

52. ______°C temperature range represents the tempering temperature for C30 steel. a) 100-150 b) 550-660 c) 860-890 d) 1400-1450

53. Annealing of steel is done to impart which one of the following property on steel? a) Hardness b) Toughness c) Ductility d) Brittleness

54. During hardening soft spots can be avoided by ______. a) using a more effective cooling medium b) protecting against in heating c) obtaining a more homogeneous structure employing annealing or normalizing before hardening d) All the above

55. _____ is/are heat treatment processes. a) Annealing b) Normalising c) Tempering d) All

56. Defect in steel due to heat treatment ______. a) Black fracture b) Warping c) Soft spot d) All

57. In normalising process, the hypo-eutectiod steel is heated from 30° C to 50° C above the upper critical temperature and then cooled in still air. a) True b) False

58. The alloying element which can replace tungsten in high speed steels is ____ a) nickel b) vanadium c) cobalt d) molybdenum

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59. In induction hardening ____ is high. a) current b) voltage c) frequency d) temperature

60. Following is a false statement about normalizing a) refine grain structure b) induces stresses c) relieve internal stresses d) None

61. Quenching is not necessary when hardening is done by ______. a) case hardening b) flame hardening c) nitriding d) All

62. In tempering ______. a) hardness & toughness decreases b) hardness decreases & toughness increases c) hardness & toughness increases d) hardness & toughness are constant

63. In induction hardening, the depth of hardening is controlled by controlling the voltage. a) Correct b) Incorrect

64. Which of the following is not equilibrium heat treatment ______. a) Austenitizing b) Annealing c) normalizing d) precipitation

65. The is not affected by _____ a) Air b) chemical composition of steel c) critical cooling rate d) quenching medium & method of quenching

66. The slowest cooling rate is obtained when steel is quenched in _____. a) air b) brine c)fused salt d) mixture of oil & water

67. The fastest cooling rate is obtained in _____ a) air b) oil c) water d) brine

68. Which one of the following is not correct ______a) Martensite has BCC structure b) Martensite is solid solution of carbon in BCC c) Austenite has FCC structure d) Martensite formed during quenching is too brittle

69. Hardenability of steel is assessed by _____. a) impact test b) jominy end-quech test c) hardness test d) non-destructive test

70. Annealing temperature is _____ a) same as normalizing temp b) greater than normalizing temp c) less than normalizing temp d) sometimes greater & sometimes lesser

71. HT that requires heating a part below A1 temp i.e. between 550 – 650 °C is called ____. a) Hardening b) Normalising c) processs annealing d) Full annealing

72. Martensite is formed from Austenite on _____ a) fast cooling b) slow cooling c) medium cooling d) None

73. Which of the processes permit the transformation of austenite to martensite, throughout the cross section of a component without cracking or distortion? a) Martempering b) Marquenching c) Both a & b d) None

74. In which of the following methods, surface of a steel component becomes hard due to phase transformation of austenite to martensite? a) Carbonitriding b) Flame hardening c) Both a & b d) None

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75. Which of the following phase is obtained as end product after complete heat treatment cycle in Austempering process? a) Austenite b) Bainite c) Martensite d) Pearlite

76. Which of the following factors increase hardenability of a metal? a) Alloying elements b) fine grain size c) high carbon content d) All

77. Which carburization method has high production rate? a) Pack Carburising b) Liquid carburizing c) Gas carburizing d) All

78. Of the following quenching media which one produces the most rapid cooling rate? a) Air b) Brine c) Oil d) Pure water

79. The Jominy end quench test is designed to indicate which one of the following? a) Cooling rate b) ductility c) Hardenability d) Hardness

80. In normalizing, one of the following is not correct ______. a) It relieves internal stresses b) it produces a uniform structure. c) the rate of cooling is rapid d) the rate of cooling is slow.

81. Annealing is generally done to impart ______. a) hardness b) softness c) brittleness d) High conductivity

82. Which process is used to harden the steel? a) Normalising b) Annelling c) Carburising d) Quenching

83. The slowest cooling rate is obtained when steel is quenched in ______a) air b) brine c) fused salt d) mixture of oil & water

84. During heat treatment, deformation & volume changes can be minimized by ______. a) slowly cooling in the martensitic range b) using surface hardening c) using steels least prone to such changes d) Any of the above

85. Quenching cracks during heat treatment can be minimized by ______. a) avoiding sharp projections & sudden transitions from thick to thin sections b) articles should be free from stress before heat treatment c) heat to minimum stable temp for hardening d) any of the above

86. Which colour of heat represents the highest temperature? a) blood red b) salmon c) dry cherry d) white

87. Which of the furnace is used to convert liquid to steel? a) cupola b) open hearth furnace c) converter d) induction arc furnace

88. Materials are softened by _____ a) carburizing b) tempering c) normalizing d) annealing

89. Austempering is the heat treatment process used to obtain greater ______a) hardness b) toughness c) brittleness d) ductility

90. Annealing involves heating the component to a temperature ______. a) slightly above critical temp b) upto critical temp c) slightly less than critical temp d) none

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91. Quenching ______. a) consists of heating the component to critical temp b) cooling rapidly c) increase hardness d) All of these

92. Tempering involves ______a) reheating the quenched component to a temp greater than critical temp. b) reheating the quenched component to a temp equal to critical temp c) increases brittleness d) none of these

93. Case carburizing involves ______a) introducing carbon at surface layer b) heating range 880 – 980 °C c) case depth upto 2 mm is possible d) All of these

94. Which of the following are true for Nitriding? a) Nascent oxygen is used b) Temp range is 490 – 590 °C c) Gaseous or liquid medium d) All the mentioned

95. Hardness of steel increases with ______a) increase of carbon % b) decrease of carbon % c) by slow cooling d) None

96. What type of furnace allows the atmosphere to consist of only air? a) Oil fired b) electric c) Both a & b d) Oil fired & gas fired

97. Which quenching medium is used to quench non-ferrous metals? a) Oil b) Brine c) Air d) Water

98. High temperature tempering develops ____ structure. a) sorbite b) troosite c) bainite d) martensite

99. In Fe-C equilibrium diagram, lower critical temperature (A1) is ______°C. a) 527 b) 727 c) 911 d) None

100. In case of flame hardening, the heat source is ______. a) LPG gas b) oxy acetylene c) fire d) flame

101. Heat treatment used for castings is ______. a) Cyaniding b) Annealing c) normalizing d) tempering

102. Which of the following is a case hardening process a) cyaniding b) nitriding c) carburizing d) all

103. The process in which carbon & get absorbed by metal surface to get it hardened is ____. a) induction hardening b) flame hardening c) cyaniding d) carburizing

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