Mechanical Engineering - Engineering Materials

41. 

Iron ore is, usually, found in the form of

A. oxides
B. carbonates
C. sulphides
D. all of these

Answer: Option D

Explanation:

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42. 

The hardness of steel increases if it contains

A. pearlite
B. ferrite
C. cementite
D. martensite

Answer: Option C

Explanation:

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43. 

In full annealing, the hypo-eutectoid steel is heated from 30° C to 50° C above the upper critical temperature and then cooled

A. in still air
B. slowly in the furnace
C. suddenly in a suitable cooling medium
D. any one of these

Answer: Option B

Explanation:

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44. 

Ferrite and pearlite makes the steel soft and ductile.

A. Agree
B. Disagree

Answer: Option A

Explanation:

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45. 

The lower critical temperature

A. decreases as the carbon content in steel increases
B. increases as the carbon content in steel increases
C. is same for all steels
D. depends upon the rate of heating

Answer: Option C

Explanation:

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