Engineering Materials

141. The correct sequence for descending order of machinability is

1. grey cast iron, low carbon steel, wrought iron
2. low carbon steel, grey cast iron, wrought iron
3. wrought iron,low carbon steel, grey cast iron
4. wrought iron, grey cast iron, low carbon steel
5. grey cast iron, wrought iron, low carbon steel.

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142. The crystal of alpha iron is

1. body centred cubic
2. face centred cubic
3. hexagonal close packed
4. cubic structure
5. orthorhombic crystal.

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143. The crystal structure of brass is

1. F.C.C.
2. B.C.C.
3. H.C.P.
4. Orthorhombic crystalline structure
5. none of the above.

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144. The crystal structure of gamma iron is

1. body centred cubic
2. face centred cubic
3. hexagonal close packed
4. cubic structure
5. orthorhombic crystal.

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145. The elastic stress strain behaviour of rubber is

1. linear
2. non-linear
3. plastic
4. no fixed relationship
5. unpredictable behaviour.

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146. The following element can’t impart high strength at elevated temperature

1. manganese
2. magnesium
3. nickel
4. silicon
5. none of the above.

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147. The following types of materials are usually the most ductile

1. face-centred cubic lattice
2. body-centred cubic lattice
3. hexagonal close-packed lattice
4. all of the above
5. none of the above.

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148. The hardness of steel increases if it contains

1. austenite
2. martensite
3. pearlite
4. cementite
5. all of the above.

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149. The hardness of steel primarily depends on

1. %age of carbon
2. %age of alloying elements
3. heat treatment employed
4. method of manufacture
5. shape of carbides and their distribution in iron.

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150. The loss of strength in compression with simultaneous gain in strength in tension due to overloading is known as

1. hysteresis
2. creep
3. visco elasticity
4. Boeschinger effect
5. inelasticity.

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