| 11. | Machinability of hard alloys and tool steels is improved by |
| a. | spherodising |
| b. | annealing |
| c. | tempering |
| d. | normalising |
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Answer: (b).annealing
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| 12. | Transformation range for ferrous material is the temperature interval during which __________ is formed during its heating. |
| a. | cementite |
| b. | austenite |
| c. | martensite |
| d. | pearlite |
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Answer: (b).austenite
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| 13. | Powder metallurgy process does not make metal powder by |
| a. | atomisation |
| b. | grinding/milling |
| c. | hammering |
| d. | electrolytic deposition |
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Answer: (c).hammering
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| 14. | In the blast furnace, incorporation of water vapour in the blast gives the following effect. |
| a. | Increases the reducing potential of the gas. |
| b. | Increases the flame temperature. |
| c. | No significant change occurs. |
| d. | Increases the hydrogen content in the metal. |
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Answer: (a).Increases the reducing potential of the gas.
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| 15. | Pick out the wrong statement. |
| a. | A ferromagnetic material becomes paramagnetic above the 'Curie temperature'. |
| b. | Permanent magnets are made of hard materials, whereas electromagnets require soft magnetic materials. |
| c. | Soft magnetic materials (e.g., pure iron) have higher permeability and low hysterisis loss and coercive forces. |
| d. | Tungsten steel and alnico are not hard magnetic materials. |
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Answer: (d).Tungsten steel and alnico are not hard magnetic materials.
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