MCQ
21. The following types of materials are usually the most ductile--
face-centred cubic lattice
body-centred cubic lattice
hexagonal close-packed lattice
all of the above
22. Pick up the wrong statement –
aluminium in steel results in excessive grain growth
manganese in steel induces hardness
nickel and chromiam in steel help in raising the elastic limit and improve the resilience and ductility
tungsten in steels improves magnetic properties and hardenability
23. Lead is poured into the joint between two pipes. These pipes may be made of--
cast iron
asbestos cement
vitrified clay
concrete
24. Which of the following iron exists 910°C?
∝-iron
δ -iron
β-iron
γ-iron
25. The lower critical point for all steels is—
600°C
700°C
723°C
913°C
26. Vanadium in high speed steels--
promotes decarburisation
provides high hot hardness
forms very hard carbides and thus increases wear resistance
promotes retention of austenite
27. Pearlite is a combination of--
ferrite and cementite
cementite and gamma iron
ferrite and austenite
ferrite and iron graphite
28. Which of the following element results in presence of free graphite in CI--
carbon
silicon
sulphur
manganese
29. Which of the following material has maximum ductility?
Mild steel
Nickel
Copper
Aluminum
30. Copper when alloyed with zinc is known as--
Brass
Babbits
Bronze
All of the above
31. Railway rails are normally made of –
mild steel
alloy steel
high carbon
tungsten steel
32. The toughness of a material --when it is heated.
increases
remain same
decrease
none
33. The machinability of steel is increased by--
silicon and sulphur
phosphorous, lead and sulphur
sulphur, graphite and aluminium
phosphorous and aluminium
34. Recrystallisation temperature can belowered by--
purification of metal
grain refinement
working at lower temperature
all of the above
35. In which forging is possible without any problem?
alloy steel
low carbon
high carbon
cast
36. The percentage of carbon in pig iron varies from--
0.1 to 12%
2.5 to 4.5%
1.5 to 2.5%
4 to 4.5%
37. The percentage of carbon in grey iron castings usually varies between-
0.5 to 1%
2.5 to 4.5%
1 to 2%
5 to 7%
38. Iron-carbon alloys containing carbon........... 4.3% are known as hyper eutectic cast irons--
equal to
leas than
more than
none
39. Amorphous material is one--
in which atoms align themselves in a geometric pattern upon solidification
in which there is no definite atomic structure and atoms exist in a random pattern just as in a liquid
which is not attacked by phosphorous
which is not attacked by phosphorous
40. Discontinous chips are formed during machining of--
brittle metal
hard metal
ductile metal
soft metal