Engineering Materials

81. In malleable iron, carbon is present in the form of

1. cementite
2. free carbon
3. flakes
4. spheroids
5. nodular aggregates of graphite.

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82. In mottled cast iron, carbon is available in

1. free form
2. combined form
3. nodular form
4. flat form
5. partly in free and partly in combined state.

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83. In nodular iron, graphite is in the form of

1. cementite
2. free carbon
3. flakes
4. spheroids
5. nodular aggregates of graphite.

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84. In which of the following cases, consideration of creep is important

1. flywheel of steam engine
2. cast iron pipes"
3. cycle chains
4. gas turbine blades
5. piston I.C. engine.

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85. Inconel is an alloy of

1. nickel, chromium and iron
2. nickel, copper
3. nickel, chromium
4. nickel, zinc
5. nickel, lead.

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86. Induction hardening is the process of

1. hardening surface of workpiece to ob-tain hard and wear resistant surface
2. heating and cooling rapidly
3. increasing hardness throughout
4. inducing hardness by continuous process
5. hardening core.

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87. Iron is

1. paramagnetic
2. ferromagnetic
3. ferroelectric
4. dielectric
5. none of the above.

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88. Isotropic materials are those which have the same

1. elastic properties in all directions
2. stresses induced in all directions
3. thermal properties in all directions
4. electric and magnetic properties in all directions
5. density throughout.

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89. 'Killed steels' are those steels

1. which are destroyed by burning
2. which after their destruction are recycled to produce fresh steel
3. which are deoxidised in the ladle with silicon and aluminium
4. in which carbon is completely burnt
5. which have poor properties due to improper manufacturing.

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90. Large forgings, crank shafts, axles normally contain carbon up to

1. 0.05 to 0.20%
2. 0.20 to 0.45%
3. 0.45 to 0.55%
4. 0.55 to 1.0%
5. 1.0 to 1.2%.

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