Engineering Materials

131. Sulphur in steel

1. acts as deoxidiser
2. reduces the grain size
3. decreases tensile strength and hardness
4. lowers the toughness and transverse ductility
5. increases hardness.

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132. Super conduction by metals is observed in the temperature range of

1. below 10°K
2. above 100°K
3. around 0°C
4. around 100°C
5. above 1000°C.

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133. Surveying tapes are made of a material having low coefficient of expansion and enough strength. The alloy used is

1. silver metal
2. duralumin
3. Hastelloy
4. monel metal
5. invar.

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134. Taps, dies and drills contain carbon

1. below 0.5%
2. below 1%
3. above 1%
4. above 2.2%
5. nil.

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135. Tensile strength of steel can be safely in-creased by

1. adding carbon up to 2.8%
2. adding carbon up to 6.3%
3. adding carbon up to 0.83%
4. adding small quantities of copper
5. adding copper and carbon.

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136. The ability of a material to resist softening at high temperature is known as

1. creep
2. hot tempering
3. hot hardness
4. fatigue
5. superhardening.

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137. The alloy used for making electrical resistances and heating elements is

1. nichrome
2. invar
3. magnin
4. elinvar
5. peiminvar.

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138. The basic constituents of Hastelloy are

1. aluminium, copper etc.
2. nickel, molybdenum etc.
3. nickel, copper, etc.
4. all of the above
5. none of the above.

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139. The composition of silver solder is

1. silver, copper, zinc
2. silver, tin, nickel
3. silver, lead, zinc
4. silver, copper, aluminium
5. silver, lead, tin.

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140. The correct composition of Babbit metal is

1. 87.75% Sn, 4% Cu, 8% Sb, 0.25% Bi
2. 90% Sn, 2% Cu, 4% Sb, 2% Bi, 2% Mg
3. 87% Sn, 4% Cu, 8% Sb, 1% Al
4. 82% Sn, 4% Cu, 8% Sb, 3% Al, 3% Mg
5. none of the above.

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