Engineering Materials top mcq

Engineering Materials top mcq

1.The compressive strength of cast iron is more than that of its

tensile strength.

Note:-

Compressive strength or compression strength is the capacity of a material or structure to withstand loads tending to reduce size, as opposed to tensile strength, which withstands loads tending to elongate.

2.When a steel containing less than 0.8% carbon is cooled slowly from temperatures above or within the critical range, it consists of

ferrite and pearlite

Note:-

Pearlite is a two-phased, layered structure composed of alternating layers of ferrite (88 wt%) and cementite (12 wt%) that occurs in some steels and cast irons.

3.Eutectoid reaction occurs at

723°C

Note:-

A eutectoid reaction is a three-phase reaction by which, on cooling, a solid transforms into two other solid phases at the same time. If the bottom of a single-phase solid field closes (and provided the adjacent two-phase fields are solid also), it does so with a eutectoid point.

4.Nickel when added to copper improves

hardness

Note:-

Hardness is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion.

5.In the lower part of the blast furnace (zone of fusion), the temperature is

1200°C to 1300°C

6.Which of the following impurity in cast iron promotes graphite nodule formation and increases the fluidity of the molten metal?

Silicon

Note:-

Silicon is a chemical element with symbol Si and atomic number 14. A hard and brittle crystalline solid with a blue-grey metallic luster, it is a tetravalent metalloid and semiconductor.

7.Inconel contains

80% nickel, 14% chromium and 6% iron

Note:-

Inconel is a family of austenitic nickel-chromium-based superalloys. Inconel alloys are oxidation-corrosion-resistant materials well suited for service in extreme environments subjected to pressure and heat. Inconel alloys are typically used in high temperature applications.

8.In a hardening process, the hypo-eutectoid steel is

heated from 30° C to 50° C above the upper critical temperature and then cooled suddenly in a suitable cooling medium.

Note:-

Hardening is a metallurgical metalworking process used to increase the hardness of a metal. The hardness of a metal is directly proportional to the uniaxial yield stress at the location of the imposed strain. A harder metal will have a higher resistance to plastic deformation than a less hard metal.

9.The ratio of the volume occupied by the atoms to the total volume of the unit cell is called

atomic packing factor

Note:-

In crystallography, atomic packing factor (APF), packing efficiency or packing fraction is the fraction of volume in a crystal structure that is occupied by constituent particles.

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

plasticity

Note:-

In physics and materials science, plasticity describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces.

11.Sulphur in cast iron

increases hardness and brittleness

12.Cementite consist of

6.67% carbon and 93.33% iron.

Note:-

Cementite is an intermetallic compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula Fe₃C. By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure.

13.Manganese is added in low carbon steel to

make the steel ductile and of good bending qualities

14.Beryllium bronze contains

97.75% copper and 2.25% beryllium

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

bosh

16.Gamma-iron occurs between the temperature range of

900°C to 1400°C.

Note:-

Austenite, also known as gamma-phase iron (γ-Fe), is a metallic, non-magnetic allotrope of iron or a solid solution of iron, with an alloying element.

17.The bond formed by transferring electrons from one atom to another is called

ionic bond

Note:-

ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds.

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

Toughness

19.Connecting rod is, usually, made from

medium carbon steel.

Note:-

medium carbon steel also known as mild steel, it is a low-cost material that is easy to shape. While not as hard as higher-carbon steels, carburizing can increase its surface hardness. Medium Carbon Steel – Composition of 0.29%-0.54% carbon, with 0.60%-1.65% manganese.

20.Which of the following inpurity in cast iron makes it hard and brittle?

Sulphur

21.Monel metal contains

68% nickel, 29% copper and 3% other constituents.

Note:-

Monel is a group of nickel alloys, primarily composed of nickel and copper, with small amounts of iron, manganese, carbon, and silicon.

22.A fine grained steel

is more ductile and has a less tendency to distort during heat treatment

23.Babbit metal contains .

88% tin, 4% copper and 8% antimony

24.A steel with 0.8% carbon is known as

eutectoid steel

25.When a steel containing more than 0.8% carbon is cooled slowly below the lower critical point, it consists of

pearlite and cementite

26.In a unit cell of a body centred cubic space lattice,

there are nine atoms.

27.Silicon in cast iron.

makes the iron soft and easily machinable

28.The process which improves the machinability of steels, but lowers the hardness and tensile strength, is

Spheroidising.

Note:-

Spheroidising is an annealing treatment for. improving cold formability and machinability of steels.

29.Which of the following iron exists at 910° C?

α-iron.

Note:-

The alpha iron (α) is a body-centered cubic (BCC) and the gamma iron (γ) is a face-centered cubic (FCC).

30.The iron ore mostly used for the production of pig iron is

Hematite.

Note:-

 Hematite, also spelled as hematite, is the mineral form of iron(III) oxide, one of several iron oxides. It is the oldest known iron oxide mineral and is widespread in rocks and soils.

Mohs scale hardness: 5.5–6.5.

31.A carbon steel having Brinell hardness number 100 should have ultimate tensile strength closer to

350 N/mm².

Note:-

BHN is designated by the most commonly used test standards (ASTM E10-14 and ISO 6506–1:2005) as HBW (H from hardness, B from Brinell and W from the material of the indenter, tungsten (wolfram) carbide). In former standards HB or HBS were used to refer to measurements made with steel indenters.

32.The steel widely used for making precision measuring instruments is

nickel steel.

Note:-

nickel steel is a type of stainless steel containing chromium and nickel.

33.The ductility is the property of a material due to which it

can be drawn into wires

34.The high speed steel has maximum percentage of

tungsten.

Note:-

High Speed Steels are high-performance special steels offering high hardness at temperatures up to 500°C and high wear resistance, thanks to alloying elements like tungsten, molybdenum, vanadium and chromium which are able to form carbides. To improve hot hardness, cobalt may also be added.

35.The essential constituent of a hardened steel is

 martensite

36.The cutting tools are made from

high speed steel

37.The approximate height of a blast furnace is

 30 m.

Note:-

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.

38.A steel alloy containing 36% nickel is called

Invar.

Note:-

Invar, also known generically as FeNi36, is a nickel–iron alloy notable for its uniquely low coefficient of thermal expansion.

39.The temperature point at which the change ends on heating the steel is called

upper critical point

40.The process of inducing carbon to low carbon steels in order to give it a hard surface is known as

carburising.

Note:-

Into Carburising process add carbon to (iron or steel), in particular by heating in the presence of carbon to harden the surface.

41.Which of the following solids are malleable and ductile?

Metallic solids

42.Thermosetting plastics are those materials which

are formed into shape under heat and pressure and results in a permanently hard product

Note:-

A thermoset, also called a thermosetting plastic, is a plastic that is irreversibly cured from a soft solid or viscous liquid, prepolymer or resin.

43.Admirality gun metal contains

88% copper, 10% tin and 2% zinc.

Note:-

Gunmetal, also called G Metal, variety of bronze, formerly used for ordnance. Modern admiralty gunmetal is composed of 88 percent copper, 10 percent tin, and 2 percent zinc and is used for gears and bearings that are to be subjected to heavy loads and low speeds.

44.The percentage of phosphorus is phosphor bronze is

0.1

Note:-

phosphor bronze is a tough, hard form of bronze containing a small amount of phosphorus, used especially for bearings.

45.For the pipe fitting like elbow, tee, union etc., which of the following is preferred?

Malleable iron.

Note:-

Malleable iron is cast as white iron, the structure being a metastable carbide in a pearlitic matrix. Through an annealing heat treatment, the brittle structure as first cast is transformed into the malleable form.

46.Chilled cast iron is produced

by quick cooling of molten cast iron.

Note:-

Chilled cast iron. Iron-carbon alloy with low graphitization factor so that chill occurs forming a graphite-free structure. The carbon is present bonded in the form of iron carbide, which is why the break surface of the material appears whitish instead of gray.

47.Silicon is added in low carbon steels to

make the steel tougher and harder

48.According to Indian standard specifications, cast iron designated by 'FG 150' means

grey cast iron with 150 MPa as minimum tensile strength

49.The red flame during the operation of a bessemer converter indicates that the

red flame does not occur during the operation of a Bessemer converter.

Note:- Bessemer converter is a steel-making process, now largely superseded, in which carbon, silicon, and other impurities are removed from molten pig iron by oxidation in a blast of air in a special tilting retort (a Bessemer converter ).

50.Phosphor bronze has

good wearing qualities and high elasticity .

Note:-

Phosphor bronze is an alloy of copper with 0.5–11% of tin and 0.01–0.35% phosphorus. The tin increases the corrosion resistance and strength of the alloy.  These alloys are notable for their toughness, strength, low coefficient of friction, and fine grain.

51.In the austempering process of heat treatment, austenite changes into

Bainite.

Note:-

Austempering is a heat treating process for medium-to-high carbon ferrous metals which produces a metallurgical structure called bainite. It is used to increase strength, toughness, and reduce distortion.

52.Which of the following material has maximum malleability?

Lead.

Note:-

Lead is a chemical element with symbol Pb and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and has a relatively low melting point.

Melting point: 327.5 °C.

Boiling point: 1,749 °C.

53.German silver contains

60.45% copper, 35.2% zinc and 5.35% nickel.

Note:-

a white alloy of nickel, zinc, and copper.

54.The machine tool guide ways are usually hardened by

flame hardening.

Note:-

Heat is applied to the part being hardened, using an oxy- acetylene (or similar gas) flame on the surface of the steel being hardened and heating the surface above the upper critical temperature before quenching the steel in a spray of water. The result is a hard surface layer ranging from 0.050" to 0.250" deep.

55.Which of the following is a case hardening process?

Carburising

Cyaniding

Nitriding

all of these

Note:-

Cyaniding

Most liquid carburizing baths contain cyanide, which introduces both carbon and nitrogen into the case.

nitriding

heat (steel) in the presence of ammonia or other nitrogenous material so as to increase hardness and corrosion resistance.

56.The austenitic stainless steel contains

18% chromium and 8% nickel.

57.The process used for relieving the internal stresses previously set up in the Metal and for increasing the machinability of steel, is

process annealing.

Note:

Annealing is a heat treatment process which alters the microstructure of a material to change its mechanical or electrical properties. Typically, in steels, annealing is used to reduce hardness, increase ductility and help eliminate internal stresses.

58.Steel containing up to 0.15% carbon, is known as

dead mild steel.

Note:-

Dead Mild Steel has a carbon content of between 0.05% and 0.15%. This gives Dead Mild Steel the property of good Ductility and the ability to be easily formed. Some of the uses of Dead Mild Steel are : Tinplate, Car Bodies, Chains, Nails, Thin Wire, etc.

59.The fuel used in a blast furnace is

coke

60.Which of the following is a point imperfection?

Vacancy

Interstitial imperfection

Frenkel imperfection

all of these

61.The process in which carbon and nitrogen both are absorbed by the metal surface to get it hardened is known as

 cyaniding

62.Muntz metal (Yellow brass) contains

60% copper and 40% zinc

63.Which of the following gives the correct order of increasing hot hardness of cutting tool materials?

High speed steel, Carbide, Diamond

64.Which of the following is a mesomorphous material?

Mica

65.The casting ability of aluminium increases when __________ is added to aluminium.

silicon

66.Manganese bronze has

high resistance to corrosion

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