Engineering Materials Practice Set-3

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

Alpha iron, beta iron and gamma iron

Alpha iron, gamma iron and delta iron

Body centered cubic iron and face centered cubic iron

Alpha iron and beta iron

2. The hardness of steel primarily depends on

Heat treatment employed

Shape of carbides and their distribution in iron

Percentage of alloying elements

Percentage of carbon

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

0.6 to 0.8%

0.4 to 0.6%

0.35 to 0.45%

0.04%

4. The machinability of steel is improved by adding

Nickel and chromium

Chromium

Nickel

Sulphur, lead and phosphorus

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

It is prone to age hardening

It can be forged

It has good machining properties

It is lighter than pure aluminium

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

By forming a bulge

By crushing into thousands of pieces

By shearing along oblique plane

In direction perpendicular to application of load

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

Copper

Chromium

Nickel

Silicon

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

Hindalium

Duralumin

Magnalium

Y-alloy

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

Brittleness

Toughness

Strength

Stiffness

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

0.55 to 1.0%

0.20 to 0.45%

0.05 to 0.20%

0.45 to 0.55%

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11. Brass contains

70 - 75% copper and rest tin

70% copper and 30% zinc

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

90% copper and 10% tin

12. Corundum contains more than 95%

Al₂O₃

SiO₂

MgO

Steel

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

Point defect

Surface defect

Line defect

None of these

14. 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

15. 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

16. Taps dies and drills contain carbon

Above 2.2%

Below 0.5%

Below 1%

Above 1%

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

Malleability

Plasticity

Elasticity

Ductility

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

H.C.P. structure

B.C.C. crystalline structure

F.C.C. crystal structure

A complex cubic structure

19. Cementite consist of

13% cementite and 87% ferrite

13% ferrite and 87% cementite

13% carbon and 87% ferrite

6.67% carbon and 93.33% iron

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

Bosh

Throat

Hearth

Stack

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

1.2%

5 to 7%

0.5 to 1%

2.5 to 4.5%

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

Machinability

Formability

Weldability

Hardenability

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

Plasticity

Ductility

Malleability

Brittleness

24. 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

25. Hematite iron ore contains iron about

70%

30%

55%

45%

26. There are fourteen atoms in a unit cell of

Body centered cubic space lattice

None of these

Close packed hexagonal space lattice

Face centered cubic space lattice

27. The tensile strength of wrought iron is maximum

Perpendicular to lines of slag distribution

None of the above

Along the lines of slag distribution

Uniform in all directions

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

Admiralty metal

Cast steel

Brass

Cast iron

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

Brittleness

Strength

Toughness

Stiffness

30. The coke in the charge of blast furnace

Supplies heat to reduce ore and melt the iron

Controls the grade of pig iron

Acts as an iron bearing mineral

Forms a slag by combining with impurities

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

Neutral

Acidic

Brittle

Basic

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

Improve mechanical properties

Induce stresses

Refine grain structure

Reduce segregation in casting

33. Cobalt in steel

Improves cutting ability and reduce hardenability

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

Gives ductility, toughness, tensile strength and anti corrosion property

Improves wear resistance, cutting ability and toughness

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

1500 VPN

600 VPN

250 VPN

1000 to 1100 VPN

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

Monel metal

Phosphor bronze

White metal

Silicon bronze

36. Points of arrest for iron correspond to

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

Stages at which properties do not change with increase in temperature

There is nothing like points of arrest

Stages at which allotropic forms change

37. Ductility of a material can be defined as

Ability to undergo large permanent deformations in compression

Ability to recover its original form

Ability to undergo large permanent deformations in tension

All of the above

38. Tungsten in steel

Improves wear resistance, cutting ability and toughness

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

Improves cutting ability and reduces hardenability

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

39. Gamma-iron occurs between the temperature ranges of

900°C to 1400°C

600°C to 900°C

400°C to 600°C

1400°C to 1530°C

40. The usual composition of a soldering alloy is

Tin and lead

Tin, lead and small percentage of antimony

Tin, lead and silver

Tin and copper

Engineering Materials Practice Set-3

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