there is no critical point
there is only one critical point
there are two critical points
there can be any numbe
✅ The correct answer is option B.
Engineering Materials MCQs
32. The portion of the blast furnace below its widest cross-section is called
hearth
stack
bosh
throat
✅ The correct answer is option C.
33. When a steel containing __________ 0.8% carbon is cooled slowly below the lower critical point, it consists of ferrite and pearlite.
equal to
less than
more than
✅ The correct answer is option B.
34. Induction hardening is basically a
carburising process
surface hardening process
core-hardening process
none of these
✅ The correct answer is option B.
35. The carbon in the pig iron varies from
0.1 to 0.5%
0.5 to 1%
1 to 5%
5 to 10%
✅ The correct answer is option C.
36. The purpose of heat treatment is to
relieve the stresses set up in the material after hot or cold working
modify the structure of the material
change grain size
any one of these
✅ The correct answer is option D.
37. A steel with 0.8% carbon is known as
eutectoid steel
hyper-eutectoid steel
hypo-eutectiod steel
none of these
✅ The correct answer is option A.
38. In basic bessemer process, the furnace is lined with
silica bricks
a mixture of tar and burnt dolomite bricks
either (a) or (b)
none of these
✅ The correct answer is option B.
39. In spheroidising process, the steel is
heated below the lower critical temperature and then cooled slowly
heated upto the lower critical temperature and then cooled in still air
heated slightly above the lower critical temperature and then cooled slowly to a temperature of 600°C
none of the above
✅ The correct answer is option C.
40. The approximate height of a blast furnace is
10 m
20 m
30 m
40 m
✅ The correct answer is option C.