Engineering Materials

121. Railway rails are normally made of

1. mild steel
2. alloy steel
3. high carbon
4. tungsten steel
5. cast iron steel.

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122. Recrystallisation temperature can belowered by

1. purification of metal
2. grain refinement
3. working at lower temperature
4. all of the above
5. none of the above.

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123. Recrystallization temperature is one

1. at which crystals first start forming from molten metal when it is cooled
2. at which new spherical crystals first begin to form from the old deformed one when a strained metal is heated
3. at which change of allotropic form takes place
4. at which crystals grow bigger in size
5. at which crystals are destroyed on heating.

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124. Slow plastic defomiation of metals under a constant stress is known as

1. creep
2. fatigue
3. endurance
4. plastic deformation
5. non-plastic deformation.

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125. Solder is an alloy consisting of

1. tin, antimony, copper
2. tin and copper
3. tin and lead
4. lead and zinc
5. lead and copper.

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126. Steel contains

1. 80% or more iron
2. 50% or more iron
3. alloying elements like chromium, tungsten nickel and copper
4. elements like phosphorus, sulphur and silicon in varying quantities
5. high quantities of sulphur.

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127. Steel made from phosphatic iron is

1. brittle
2. hard
3. ductile
4. tough
5. malleable.

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128. Stress relaxation is- the phenomenon

1. in which parts are not loaded
2. in which stress remains constant on in-creasing load
3. in which deformation tends to loosen the joint and produces a stress reduced
4. stress reduces on increasing load
5. none of the above.

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129. Structural steel contains following principal alloying elements

1. nickel, chromium and manganese
2. tungsten, molybdenum and phosphorous
3. lead, tin, aluminium
4. zinc, sulphur, and chromium
5. none of the above.

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130. Sulphur in pig iron tends to make it

1. hard’
2. soft
3. ductile
4. tough
5. malleable.

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