Engineering Materials Practice Set-3

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

Cast iron

Brass

Cast steel

Admiralty metal

2. The hardness of steel primarily depends on

Heat treatment employed

Shape of carbides and their distribution in iron

Percentage of carbon

Percentage of alloying elements

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

250 VPN

1500 VPN

1000 to 1100 VPN

600 VPN

4. Corundum contains more than 95%

Al₂O₃

SiO₂

Steel

MgO

5. Points of arrest for iron correspond to

Stages at which allotropic forms change

Stages at which properties do not change with increase in temperature

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

There is nothing like points of arrest

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

Body centered cubic iron and face centered cubic iron

Alpha iron, gamma iron and delta iron

Alpha iron, beta iron and gamma iron

Alpha iron and beta iron

7. The usual composition of a soldering alloy is

Tin and copper

Tin, lead and silver

Tin, lead and small percentage of antimony

Tin and lead

8. Cobalt in steel

Improves wear resistance, cutting ability and toughness

Gives ductility, toughness, tensile strength and anti corrosion property

Improves cutting ability and reduce hardenability

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

9. There are fourteen atoms in a unit cell of

Close packed hexagonal space lattice

None of these

Body centered cubic space lattice

Face centered cubic space lattice

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

2.5 to 4.5%

5 to 7%

0.5 to 1%

1.2%

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11. Brass contains

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

70% copper and 30% zinc

70 - 75% copper and rest tin

90% copper and 10% tin

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

Plasticity

Elasticity

Ductility

Malleability

13. Tungsten in steel

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

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

Improves cutting ability and reduces hardenability

Improves wear resistance, cutting ability and toughness

14. The machinability of steel is improved by adding

Nickel and chromium

Nickel

Chromium

Sulphur, lead and phosphorus

15. Taps dies and drills contain carbon

Above 1%

Below 1%

Below 0.5%

Above 2.2%

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

Machinability

Hardenability

Formability

Weldability

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

A complex cubic structure

H.C.P. structure

F.C.C. crystal structure

B.C.C. crystalline structure

18. The unit cells

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

Have the same orientation and their similar faces are parallel

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

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

Brittleness

Toughness

Stiffness

Strength

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

Phosphor bronze

White metal

Silicon bronze

Monel metal

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21. Ductility of a material can be defined as

Ability to undergo large permanent deformations in tension

All of the above

Ability to undergo large permanent deformations in compression

Ability to recover its original form

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

Chromium

Copper

Silicon

Nickel

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

0.4 to 0.6%

0.6 to 0.8%

0.35 to 0.45%

0.04%

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

Plasticity

Ductility

Brittleness

Malleability

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

Line defect

Point defect

None of these

Surface defect

26. The coke in the charge of blast furnace

Acts as an iron bearing mineral

Controls the grade of pig iron

Forms a slag by combining with impurities

Supplies heat to reduce ore and melt the iron

27. Hematite iron ore contains iron about

30%

45%

55%

70%

28. 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

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

Hindalium

Y-alloy

Magnalium

Duralumin

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

Hearth

Throat

Stack

Bosh

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31. Gamma-iron occurs between the temperature ranges of

400°C to 600°C

900°C to 1400°C

600°C to 900°C

1400°C to 1530°C

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 statement is incorrect about duralumin?

It can be forged

It is lighter than pure aluminium

It is prone to age hardening

It has good machining properties

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

30 : 20 : 30 : 20

40 : 30 : 20 : 10

50 : 20 : 10 : 20

50 : 20 : 20 : 10

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

Improve mechanical properties

Refine grain structure

Induce stresses

Reduce segregation in casting

36. Cementite consist of

6.67% carbon and 93.33% iron

13% cementite and 87% ferrite

13% carbon and 87% ferrite

13% ferrite and 87% cementite

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

By crushing into thousands of pieces

By shearing along oblique plane

By forming a bulge

In direction perpendicular to application of load

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

Neutral

Acidic

Basic

Brittle

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

0.05 to 0.20%

0.55 to 1.0%

0.20 to 0.45%

0.45 to 0.55%

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

Tungsten, chromium, titanium

Vanadium, chromium, tungsten

Tungsten, titanium, vanadium

Chromium, titanium, vanadium

Engineering Materials Practice Set-3

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