Engineering Materials Practice Set-3

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1. The defect which takes place due to imperfect packing of atoms during crystallization is known as

None of these

Point defect

Surface defect

Line defect

2. Tungsten in steel

Refines grain size and produces less tendency to carburisation, improves corrosion and heat resistant properties

Gives ductility, toughness, tensile strength and anti-corrosion properties

Improves wear resistance, cutting ability and toughness

Improves cutting ability and reduces hardenability

3. The surface hardness of the following order is achieved by nitriding operation

250 VPN

1000 to 1100 VPN

1500 VPN

600 VPN

4. A specimen of aluminium metal when observed under microscope shows

H.C.P. structure

F.C.C. crystal structure

B.C.C. crystalline structure

A complex cubic structure

5. Corundum contains more than 95%

Steel

Al₂O₃

SiO₂

MgO

6. The hardness of steel primarily depends on

Percentage of carbon

Percentage of alloying elements

Heat treatment employed

Shape of carbides and their distribution in iron

7. Which of the following statement is incorrect about duralumin?

It is lighter than pure aluminium

It can be forged

It is prone to age hardening

It has good machining properties

8. Hematite iron ore contains iron about

55%

70%

45%

30%

9. The coke in the charge of blast furnace

Acts as an iron bearing mineral

Supplies heat to reduce ore and melt the iron

Forms a slag by combining with impurities

Controls the grade of pig iron

10. Points of arrest for iron correspond to

Stages at which further heating does not increase temperature for some time

Stages at which allotropic forms change

There is nothing like points of arrest

Stages at which properties do not change with increase in temperature

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11. Gamma-iron occurs between the temperature ranges of

1400°C to 1530°C

900°C to 1400°C

400°C to 600°C

600°C to 900°C

12. The usual composition of a soldering alloy is

Tin and copper

Tin and lead

Tin, lead and silver

Tin, lead and small percentage of antimony

13. The main alloying elements high speed steel in order of increasing proportion are

Chromium, titanium, vanadium

Vanadium, chromium, tungsten

Tungsten, titanium, vanadium

Tungsten, chromium, titanium

14. Which of the following represents the allotropic forms of iron?

Alpha iron, gamma iron and delta iron

Body centered cubic iron and face centered cubic iron

Alpha iron and beta iron

Alpha iron, beta iron and gamma iron

15. Ductility of a material can be defined as

Ability to recover its original form

Ability to undergo large permanent deformations in compression

Ability to undergo large permanent deformations in tension

All of the above

16. Which of the following property is desirable for materials used in tools and machines?

Plasticity

Ductility

Malleability

Elasticity

17. The tensile strength of wrought iron is maximum

Along the lines of slag distribution

Uniform in all directions

Perpendicular to lines of slag distribution

None of the above

18. Which of the following elements does not impart hardness to steel?

Copper

Silicon

Chromium

Nickel

19. In compression, a prism of brittle material will break

By shearing along oblique plane

In direction perpendicular to application of load

By forming a bulge

By crushing into thousands of pieces

20. There are fourteen atoms in a unit cell of

Body centered cubic space lattice

Close packed hexagonal space lattice

None of these

Face centered cubic space lattice

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21. Brass contains

70% copper and 30% zinc

85 - 92% copper and rest tin with little lead and nickel

70 - 75% copper and rest tin

90% copper and 10% tin

22. The metal suitable for bearings subjected to heavy loads, is

White metal

Silicon bronze

Monel metal

Phosphor bronze

23. Large forgings, crank shafts, axles normally contain carbon up to

0.55 to 1.0%

0.05 to 0.20%

0.20 to 0.45%

0.45 to 0.55%

24. The machinability of steel is improved by adding

Nickel and chromium

Sulphur, lead and phosphorus

Nickel

Chromium

25. Cementite consist of

13% cementite and 87% ferrite

13% carbon and 87% ferrite

6.67% carbon and 93.33% iron

13% ferrite and 87% cementite

26. Cobalt in steel

Gives ductility, toughness, tensile strength and anti corrosion property

Improves cutting ability and reduce hardenability

Improves wear resistance, cutting ability and toughness

Refines grain size and produces less tendency to carburisation, improve corrosion and heat resistant proper ties

27. If a refractory contains high content of silicon, it means refractory is

Brittle

Acidic

Basic

Neutral

28. The percentage of carbon in grey iron castings usually varies between

0.5 to 1%

5 to 7%

2.5 to 4.5%

1.2%

29. Which is false statement about normalizing? Normalizing is done to

Improve mechanical properties

Induce stresses

Refine grain structure

Reduce segregation in casting

30. The property of a material which enables it to retain the deformation permanently, is called

Ductility

Malleability

Brittleness

Plasticity

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31. The portion of the blast furnace below its widest cross-section is called

Hearth

Bosh

Stack

Throat

32. The ability of a material to resist fracture due to high impact loads, is called

Toughness

Strength

Stiffness

Brittleness

33. Which of the following metal shrinks most from molten state to solid state?

Brass

Cast iron

Cast steel

Admiralty metal

34. Which of the following property is desirable in parts subjected to shock and impact loads?

Brittleness

Stiffness

Strength

Toughness

35. The aluminium alloy made by melting aluminium with 2 to 10% magnesium and 1.75% copper is called

Duralumin

Y-alloy

Magnalium

Hindalium

36. In low carbon steels, presence of small quantities of sulphur improves

Formability

Hardenability

Weldability

Machinability

37. Taps dies and drills contain carbon

Below 0.5%

Above 2.2%

Below 1%

Above 1%

38. According to Indian standard specifications, plain carbon steel designated by 40 C8 means that the carbon content is

0.4 to 0.6%

0.04%

0.6 to 0.8%

0.35 to 0.45%

39. Alnico, an alloy used extensively for permanent magnets contains iron, nickel, aluminium and cobalt in the following ratio

50 : 20 : 20 : 10

30 : 20 : 30 : 20

40 : 30 : 20 : 10

50 : 20 : 10 : 20

40. The unit cells

May be defined as the smallest parallelepiped which could be transposed in three coordinate directions to build up the space lattice

Have the same orientation and their similar faces are parallel

All of the above

Contain the smallest number of atoms which when taken together have all the properties of the crystals of the particular metal

Engineering Materials Practice Set-3

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