| 1. | After hearing up to required hardening temperature, why must tool steels be quenched ? | |
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to induce internal stresses
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to build up hardening structure
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to fall off the scale
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to return it to its original structure
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Report Question| 2. | The process of inducing carbon to low carbon Steels to get a hard surface is called ? | |
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annealing
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case hardening
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carburizing
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normalising
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| 3. | liquid carbonising is done in a heated salt bath. Which one of the following is not a carbonising salt ? | |
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sodium carbonate
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sodium sulfate
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sodium cyanide
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barium chloride
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| 4. | Why line stone is added to the ore in the blast furnace ? | |
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To burnt the carbon in coke
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To form molten slag
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To increase the melting point of ore
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To supply the oxygen
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| 5. | Which one of the following process is used for hardening the surface of tool steel ? | |
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carbonising
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cyaniding
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induction hardening
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hardening
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| 6. | while heating plane carbon steel, the temperature at which __________ ? | |
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austenite
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ferrite
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cementite
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pearlite
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| 7. | What is the percentage of carbon in mild steel ? | |
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0.3 to 0.6%
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0.6 to 1.7%
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0.1 to 0.15%
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0.15 to 0.3%
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| 8. | One component of steel is heated to 830°c, shocked at it for some time and then quenched in oil. Again it is heated to 600°c and quenched in oil. Name this process of heat treatment ? | |
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hardening & tempering
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tempering
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annealing
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normalising
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| 9. | High speed steel is tempered at ? | |
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220°c to 230°c
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230°c to 270°c
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280°c to 400°c
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550°c to 600°c
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| 10. | case hardening is a method of producing hard skin in the surface of ? | |
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high carbon steel
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high speed steel
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mild steel
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cast iron
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