Engineering Materials

161. The temperature at which ferromagnetic alpha iron transforms to paramagnetic alpha iron is

1. 770°C
2. 910°C
3. 1050°C
4. below recrystallisation temperature
5. above recrystallization temperature.

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162. The tensile strength of wrought iron is maximum

1. along the lines of slag distribution
2. perpendicular to lines of slag distribution
3. uniform in all directions
4. unpredictable
5. none of the above.

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163. The transistor is made of

1. silver
2. gold
3. copper
4. germanium
5. german silver.

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164. The ultimate tensile strength and yield strength of most of the metals, when temperature falls from 0 to l00°C will

1. increase
2. decrease
3. remain same
4. first increase and then decrease
5. show unpredictable behaviour.

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165. The ultimate tensile strength of low carbon steel by working at a high strain rate will

1. decrease
2. increase
3. remain constant
4. first increase and then decrease
5. first decrease and then increase.

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166. The unique property of cast iron is its high

1. malleability
2. ductility
3. surface finish
4. damping characteristics
5. hardness.

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167. The usual composition of a soldering alloy is

1. tin, lead and small percentage of antimony
2. tin and lead
3. tin, lead and silver
4. tin and copper
5. tin, copper and lead.

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168. Tungsten in high speed steel provides

1. hot hardness
2. toughness
3. wear resistance
4. sharp cutting edge
5. cold hardness.

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169. Tungsten in steel

1. improves wear resistance, cutting ability and toughness
2. refines grain size and produces less tendency to carburisation, improves corrosion and heat resistant properties
3. improves cutting ability and reduces hardenability
4. gives ductility, toughness, tensile strength and anticorrosion properties
5. raises its melting point.

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170. Vanadium in high speed steels

1. promotes decarburisation
2. provides high hot hardness
3. forms very hard carbides and thus in-creases wear resistance
4. promotes retention of austenite
5. increases toughness.

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