Engineering Materials Practice Set-3

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1. Brass contains

90% copper and 10% tin

70 - 75% copper and rest tin

70% copper and 30% zinc

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

2. Cementite consist of

13% cementite and 87% ferrite

6.67% carbon and 93.33% iron

13% ferrite and 87% cementite

13% carbon and 87% ferrite

3. 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%

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

B.C.C. crystalline structure

A complex cubic structure

F.C.C. crystal structure

H.C.P. structure

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

Silicon

Copper

Nickel

Chromium

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

Strength

Toughness

Stiffness

Brittleness

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

Alpha iron and beta iron

Alpha iron, gamma iron and delta iron

Body centered cubic iron and face centered cubic iron

Alpha iron, beta iron and gamma iron

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

Vanadium, chromium, tungsten

Tungsten, titanium, vanadium

Chromium, titanium, vanadium

Tungsten, chromium, titanium

9. 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

10. The coke in the charge of blast furnace

Controls the grade of pig iron

Forms a slag by combining with impurities

Acts as an iron bearing mineral

Supplies heat to reduce ore and melt the iron

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11. 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

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

Ductility

Malleability

Plasticity

Elasticity

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

Ductility

Plasticity

Malleability

Brittleness

14. Tungsten in steel

Improves cutting ability and reduces hardenability

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 wear resistance, cutting ability and toughness

15. Taps dies and drills contain carbon

Above 1%

Above 2.2%

Below 0.5%

Below 1%

16. The tensile strength of wrought iron is maximum

Perpendicular to lines of slag distribution

Uniform in all directions

Along the lines of slag distribution

None of the above

17. The usual composition of a soldering alloy is

Tin, lead and small percentage of antimony

Tin, lead and silver

Tin and copper

Tin and lead

18. 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

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

1.2%

2.5 to 4.5%

0.5 to 1%

5 to 7%

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

Surface defect

None of these

Line defect

Point defect

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21. Hematite iron ore contains iron about

45%

70%

30%

55%

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

Induce stresses

Reduce segregation in casting

Refine grain structure

Improve mechanical properties

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

0.20 to 0.45%

0.45 to 0.55%

0.55 to 1.0%

0.05 to 0.20%

24. 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

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

Brass

Cast steel

Admiralty metal

Cast iron

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

Duralumin

Magnalium

Hindalium

Y-alloy

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

1000 to 1100 VPN

250 VPN

1500 VPN

600 VPN

28. Points of arrest for iron correspond to

Stages at which properties do not change with increase in temperature

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

29. The unit cells

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

All of the above

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

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

Hardenability

Machinability

Weldability

Formability

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

Phosphor bronze

White metal

Monel metal

Silicon bronze

32. Cobalt in steel

Improves cutting ability and reduce hardenability

Gives ductility, toughness, tensile strength and anti corrosion property

Improves wear resistance, cutting ability and toughness

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

33. There are fourteen atoms in a unit cell of

None of these

Body centered cubic space lattice

Close packed hexagonal space lattice

Face centered cubic space lattice

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

Brittle

Neutral

Acidic

Basic

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

By shearing along oblique plane

By forming a bulge

In direction perpendicular to application of load

By crushing into thousands of pieces

36. Corundum contains more than 95%

MgO

Steel

Al₂O₃

SiO₂

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

Stiffness

Toughness

Strength

Brittleness

38. The machinability of steel is improved by adding

Nickel and chromium

Chromium

Nickel

Sulphur, lead and phosphorus

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

It can be forged

It is prone to age hardening

It has good machining properties

It is lighter than pure aluminium

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

Throat

Bosh

Stack

Hearth

Engineering Materials Practice Set-3

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