Mechanical Engineering - Engineering Materials

31. 

In the lower part of the blast furnace (zone of fusion), the temperature is

A. 400° to 700°C
B. 800°C to 1000°C
C. 1200°C to 1300°C
D. 1500°C to 1700°C

Answer: Option C

Explanation:

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32. 

Which of the following impurity in cast iron promotes graphite nodule formation and increases the fluidity of the molten metal?

A. Silicon
B. Sulphur
C. Manganese
D. Phosphorus

Answer: Option A

Explanation:

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33. 

Which of the following statement is wrong?

A. A steel with 0.8% carbon is wholly pearlite
B. The amount of cementite increases with the increase in percentage of carbon in iron
C. A mechanical mixture of 87% cementite and 13% ferrite is called pearlite
D. The cementite is identified as round particles in the structure

Answer: Option C

Explanation:

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34. 

Inconel contains

A. 65% nickel, 15% chromium and 20% iron
B. 68% nickel, 29% copper and 3% other constituents
C. 80% nickel and 20% chromium
D. 80% nickel, 14% chromium and 6% iron

Answer: Option D

Explanation:

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35. 

In a hardening process, the hypo-eutectoid steel is

A. heated from 30° C to 50° C above the upper critical temperature and then cooled in still air
B. heated from 30° C to 50° C above the upper critical temperature and then cooled suddenly in a suitable cooling medium
C. heated from 30° C to 50° C above the upper critical temperature and then cooled slowly in the furnace
D. heated below or close to the lower critical temperature and then cooled slowly

Answer: Option B

Explanation:

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