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Multiple choice question for engineering

Set 1

1. The eutectic point in the iron-iron carbide phase diagram occurs at __________ weight % composition of carbon.
a) 0.022
b) 0.77
c) 2.11
d) 4.30

View Answer

Answer: d [Reason:] The iron-iron carbide equilibrium diagram is constructed by plotting the composition of carbon against the temperature. At 4.3 weight % of carbon, eutectic point is formed.

2. At what temperature does δ ferrite melt?
a) 1674 F
b) 1990 F
c) 2541 F
d) 2800 F

View Answer

Answer: d [Reason:] δ ferrite is formed as a BCC phase due to heating of austenite at 2541 F. This δ ferrite finally melts at 2800 F and these changes are plotted on the iron-iron carbide equilibrium diagram.

3. What is the solubility of α ferrite at 0oC?
a) 0.1%
b) 0.02%
c) 0.005%
d) 0.0004%

View Answer

Answer: c [Reason:] α ferrite is an interstitial solid solution of carbon in a BCC crystal lattice. It has a solubility of 0.02% at 723oC and decreases to 0.005% at 0oC.

4. What is the crystal structure of austenite upon heating?
a) Body-centered cubic
b) Face-centered cubic
c) Hexagonal closely packed
d) Body-centered tetrahedral

View Answer

Answer: b [Reason:] At room temperature, ferrite exists as a BCC crystal as seen on the iron-iron carbide equilibrium diagram. Upon heating, this changes into austenite in FCC form at 1674 F.

5. How much iron does cementite contain?
a) 6.67%
b) 24.23%
c) 73.4%
d) 93.3%

View Answer

Answer: d [Reason:] Cementite is an intermetallic compound of iron-carbon (Fe3C). It has a solubility that is negligible with a composition of 6.67% C and 93.3% Fe.

6. What is the maximum solubility of carbon in austenite at 1148oC?
a) 0.09%
b) 0.8%
c) 2.08%
d) 14.35%

View Answer

Answer: c [Reason:] Austenite is an FCC crystal with a solubility of 2.08% at 1148oC which decreases to 0.8% at 723oC. δ ferrite has a maximum solid solubility of 0.09% at 1465.

7. At what temperature does peritectic reaction occur?
a) 1778oC
b) 1495oC
c) 1148oC
d) 723oC

View Answer

Answer: b [Reason:] In a peritectic reaction, 0.53% C of liquid combines with 0.09% C of ferrite at 1495oC. This results in the formation of ϒ austenite (0.17% of C).

8. Peritectic reactions are applicable for carbon contents up to _________
a) 0.1%
b) 0.26%
c) 0.55%
d) 0.96%

View Answer

Answer: c [Reason:] In a peritectic reaction, 0.53% C of liquid combines with 0.09% C of ferrite at 1495oC. This results in the formation of ϒ austenite (0.17% of C). This reaction affects only solidification of steels with less than 0.55% carbon.

9. How much austenite does eutectic reaction form?
a) 4.3%
b) 6.67%
c) 11.28%
d) 17.89%

View Answer

Answer: a [Reason:] In a eutectic reaction, 4.7% C of liquid at 1148oC forms ϒ austenite (2.08% of C) and Fe3C (6.67% of C). This reaction holds great importance for cast irons.

10. At what temperature does eutectoid reaction occur?
a) 418oC
b) 666oC
c) 723oC
d) 928oC

View Answer

Answer: c [Reason:] In a eutectoid reaction, 0.8% C of ϒ austenite at 723oC forms α ferrite (0.02% of C) and Fe3C (6.67% of C). This reaction holds great importance for heat treatment of steels.

Set 2

1. What is the specific gravity of magnesium?
a) 1.74
b) 2.7
c) 6.3
d) 8.9

View Answer

Answer: a [Reason:] Magnesium is a silvery-white metal which has a specific gravity of only 1.74. It also has a low weight of 1.73 gm/cu cm. The specific gravities of aluminum and copper are 2.7 and 8.9 respectively.

2. What is the melting point of magnesium?
a) 419oC
b) 650oC
c) 1091oC
d) 2562oC

View Answer

Answer: b [Reason:] Magnesium is a common element which has a melting point of 650oC and a boiling point of 1091oC. It weighs less than aluminum, iron, and steel. It has the lowest density among common structural elements.

3. Which of the following is not a property of magnesium?
a) Low strength
b) Vulnerable to corrosion
c) Expensive
d) Heavyweight

View Answer

Answer: d [Reason:] Pure magnesium is not used due to its low strength. It is also prone to corrosion, due to which it is usually painted on. Since magnesium is costly, it is used only in cases where weight is a priority. This comes to use due to its low weight.

4. Magnalium is an alloy of magnesium, ________
a) Nickel and Tin
b) Zinc and Tin
c) Nickel and Zinc
d) Zirconium and Zinc

View Answer

Answer: a [Reason:] Magnalium, although considered an aluminum alloy, may contain over 50% magnesium and small amounts of nickel and tin. They are commonly used for engineering applications and pyrotechnics.

5. How does a high amount of magnesium affect alloys?
a) Increases strength
b) Increases corrosion resistance
c) Lowers density
d) Becomes brittle

View Answer

Answer: d [Reason:] Alloys with around 50% magnesium are more brittle and prone to corrosion. However, lesser quantities (5%) result in increased strength, corrosion resistance, low density, and weldability.

6.Dow metal contains ______ of magnesium.
a) 0%
b) 5%
c) 50%
d) 90%

View Answer

Answer: d [Reason:] Dow metal is an alloy of magnesium which contains 90% magnesium, 10% aluminum, and a small amount of manganese. It is extremely lightweight and easy to weld and machine. They are commonly employed in automobile and aircraft applications.

7. Which of the following is a type of aluminum alloy with magnesium?
a) Mag-Thor
b) Magnox
c) Birmabright
d) Elektron

View Answer

Answer: c [Reason:] Birmabright is an aluminum alloy containing 1-7% magnesium and less than 1% manganese. They have good weldability, and corrosion resistance to seawater. The leftover choices are a few magnesium alloys.

8. A magnesium alloy containing 3% rare earth metal exhibits which of the following characteristics?
a) Creep resistance up to 250oC
b) Good founding properties
c) Die-casting alloy
d) Good overall properties

View Answer

Answer: a [Reason:] A magnesium alloy containing rare earth metal (3%) is a type of cast alloy. It also contains 2.5% of zinc and 0.6% zirconium. It has a creep resistance up to 250oC. It is also pressure tight, weldable, and has excellent castability.

9. Which of the following alloys is used in nuclear reactors?
a) Elektron
b) Magnox
c) Mag-Thor
d) Pyrotechnics

View Answer

Answer: b [Reason:] Magnox is a magnesium alloy used for which is used to contain fission products in nuclear reactors. It stands for Magnesium Non-Oxidising. Elektron is mainly used in aerospace and race car applications, whereas Mag-Thor is used in aerospace industry. Megnelium is used in pyrotechnics.

Set 3

1. The continuous phase of a composite material is known as its _______
a) dispersed phase
b) surrounding phase
c) matrix phase
d) fiber phase

View Answer

Answer: c [Reason:] Composite materials contain mostly two phases: matrix and dispersed phase. Matrix phase is a continuous phase which tends to bind the fibers together. It also protects them from damage and is used to transmit the load.

2. Which of the following structures represents that of a fiber composite?
a) engineering-materials-metallurgy-questions-answers-mcqs-q2a
b) engineering-materials-metallurgy-questions-answers-mcqs-q2a
c) engineering-materials-metallurgy-questions-answers-fibre-reinforced-composites-q2c
d) engineering-materials-metallurgy-questions-answers-fibre-reinforced-composites-q2d

View Answer

Answer: c [Reason:] Fiber-reinforced composites are those which contain fiber form in its dispersed phase. When these fibers are parallel to each other, they exhibit high strength.

3. How is the critical length or a composite material defined?
engineering-materials-metallurgy-questions-answers-fibre-reinforced-composites-q3

View Answer

Answer: b [Reason:] The critical length of a material is determined using the diameter of the fiber, ultimate strength, and its yield strength. The critical length of the fiber is required for strengthening of the composite materials.

4. The classification of fibers having thin crystals is known as _______
a) Whisker
b) Fiber
c) Wires
d) Matrix

View Answer

Answer: a [Reason:] Whiskers are thin single crystals having an extremely large length-to-diameter ratio. Due to their small size, they have high crystalline perfection. Fibers are polycrystalline materials of small diameters, whereas wires have large diameters.

5. Which of the following materials are common for whiskers?
a) Graphite, silicon carbide
b) Glass, boron
c) Steel, tungsten
d) Polymers, ceramics

View Answer

Answer: a [Reason:] Whiskers are single crystals having large ratios of length to diameter. The common materials are graphite, silicon nitride, aluminum oxide etc. Glass and boron fall under the category of polymers of fibers. Steel, tungsten, and molybdenum are commonly used as wires.

6. Kevlar is a ______ type of material
a) Glass
b) Thermoplastic
c) Whisker
d) Polymer

View Answer

Answer: d [Reason:] Kevlar is a polymer type of fiber material. Kevlar-epoxy and Kevlar-polyester are common fiber reinforced composites commonly used in aerospace applications, sports goods, flak jackets etc.

7. Which of the following is not a characteristic trait of composite materials?
a) High strength, toughness, modulus
b) Lightweight
c) Easy to assemble
d) Sensitive to temperature change

View Answer

Answer: d [Reason:] Composite materials have great mechanical properties, corrosion resistance, are easy to assemble, and light in weight in case of fiber composites. They aren’t very sensitive to thermal shocks and temperature changes. However, they are more expensive than conventional materials.

8. How much SiO2 is present in the glass which is drawn into fibers?
a) 55%
b) 15%
c) 10%
d) 4%

View Answer

Answer: a [Reason:] Glass which is rolled into thin fibers is known as E-glass. This glass contains 55% of SiO2 and Al2O3(15%), B2O32 (10%), and MgO (4%). It is quite the preferred type of fiber-reinforcement material.

9. Fiberglass materials have a usable temperature up to ______
a) 50oC
b) 100oC
c) 200oC
d) 500oC

View Answer

Answer: c [Reason:] Fiberglass materials have a low service temperature which is below 200oC. This is despite the fact that they usually have high strength. These materials also have a great impact resistance and are extremely flexible.

10. What is the purpose of a fiberglass that is made as a thread?
a) Insulating material
b) Conductive material
c) Heat resistant
d) Cloth

View Answer

Answer: d [Reason:] Fiberglass is either made into a staple or thread. The thread type is used to make cloth for various applications. It is also colored and can be manufactured by a continuous process. Staple type (up to 15 inches long), on the other hand, is used as an insulating material.

11. The below figure depicts the structure of ________ composite materials.
engineering-materials-metallurgy-questions-answers-other-composites-q4
a) Discontinuous
b) Aligned
c) Laminate
d) Dispersion-strengthened

View Answer

Answer: c [Reason:] A laminar composite is a subcategory type of structural composites with a varying orientation for each layer. These composite materials are used for their high strength.

12. The below figure is an example of ______ type of structural composites.
engineering-materials-metallurgy-questions-answers-other-composites-q5
a) Laminar
b) Sandwich panel
c) Discontinuous
d) Randomly oriented

View Answer

Answer: b [Reason:] Sandwich panels are a type of structural composites having a low-density material covered by layers of high-density material on its faces. Aluminum alloys and fiber-reinforced plastics are commonly used as face materials which bear the load. Randomly oriented composite is a type of discontinuous composite, which itself is a type of fiber-reinforced composite.

13. Manufacturing of components having continuous lengths and constant cross-sectional shape is done by _____ process.
a) Roving
b) Pultrusion
c) Curing
d) Pulling

View Answer

Answer: b [Reason:] Pultrusion is a process used to fabricate continuous fiber-reinforced plastics. By this method, they can work at high production rates, thereby making it less expensive. It is also easily automated.

14. What amount of principle reinforcement materials is used in pultrusion process?
a) 10-20%
b) 25-35%
c) 40-70%
d) 75-90%

View Answer

Answer: c [Reason:] The principle reinforcements used in pultrusion process are glass, carbon and aramid fibers. These are added in concentrations between 40 to 70%. The matrix materials used are polyesters, vinyl esters, and epoxy resins.

Set 4

1. The tendency of a deformed solid to regain its actual proportions instantly upon unloading known as
______________
a) Perfectly elastic
b) Delayed elasticity
c) Inelastic effect
d) Plasticity

View Answer

Answer: a [Reason:] If the recovery of the solid is instantaneous and complete, it is known as perfectly elastic. Delayed elasticity is defined as the steady mode of solid recuperation, while the inelastic effect is when the recuperation of deformed solid is partial. Plasticity is the contradictory occurrence of elasticity.

2. How is Young’s modulus of elasticity defined?
engineering-materials-metallurgy-questions-answers-mechanical-properties-q2

View Answer

Answer: c [Reason:] The ratio of load to the area engineering-materials-metallurgy-questions-answers-mechanical-properties-q2-1 is the description of stress on the solid. The ratio of alteration in length to its original length engineering-materials-metallurgy-questions-answers-mechanical-properties-q2-2 is the description of strain on the solid. Young’s modulus of elasticity is defined as the ratio of stress on the solid to the strain of the solid engineering-materials-metallurgy-questions-answers-mechanical-properties-q2-3 The ratio of the mass of the solid to its volume engineering-materials-metallurgy-questions-answers-mechanical-properties-q2-4is defined as density.

3. The permanent mode of deformation of a material known as _____________
a) Elasticity
b) Plasticity
c) Slip deformation
d) Twinning deformation

View Answer

Answer: b [Reason:] Plasticity is defined as the property of a material due to which it is permanently deformed due to loading. Elasticity is the temporary form of deformation. Twinning and Slip are mechanisms of Plastic deformation.

4. The ability of materials to develop a characteristic behavior under repeated loading known as ___________
a) Toughness
b) Resilience
c) Hardness
d) Fatigue

View Answer

Answer: d [Reason:] Toughness is the ability of a material to absorb energy during deformation, while resilience is its capacity to absorb the energy. Hardness is the knack of a material to defy indentation. The ability of a material to develop a characteristic behavior under repeated loading is known as fatigue.

5. What is the unit of tensile strength of a material?
a) engineering-materials-metallurgy-questions-answers-mechanical-properties-q5
b) kg/cm2
c) engineering-materials-metallurgy-questions-answers-mechanical-properties-q5-2
d) cm2/kg

View Answer

Answer: b [Reason:] Tensile strength is defined as the ratio of maximum load (kg) applied to its cross-sectional area (cm2). Young’s modulus of elasticity is defined as the ratio of stress on the solid to the strain of the solid. The remaining choices given are reciprocals of same.

6. Which of the following factors affect the mechanical properties of a material under applied loads?
a) Content of alloys
b) Grain size
c) Imperfection and defects
d) Shape of material

View Answer

Answer: d [Reason:] Contents of alloys improve or decrease the hardness and strength of materials. Finer grain sizes improve the strength of the material. Imperfection and defects reduce the strength of the material. Shape, however, has little or no effect on the material.

7. The ability of a material to resist plastic deformation known as _____________
a) Tensile strength
b) Yield strength
c) Modulus of elasticity
d) Impact strength

View Answer

Answer: b [Reason:] The point of stretching where it increases suddenly is known as yield strength, i.e. the region where the stretch is elastic. Tensile strength is the force needed to fracture the material. Impact strength is the capacity of a material to resist shock energy before a fracture.

8. The ability of a material to be formed by hammering or rolling is known as _________
a) Malleability
b) Ductility
c) Harness
d) Brittleness

View Answer

Answer: a [Reason:] The capacity of a material to withstand deformation under compression, i.e. hammering is known as malleability. The capacity of a material to withstand deformation under tension, i.e. wire drawing is known as ductility. Hardness is the knack of a material to oppose indentation. Brittleness is the tendency to fracture without deformation of the material.

9. What type of wear occurs due to an interaction of surfaces due to adhesion of the metals?
a) Adhesive wear
b) Abrasive wear
c) Fretting wear
d) Erosive wear

View Answer

Answer: a [Reason:] Adhesive wear occurs due to frictional contact between metals. Abrasive wear occurs due to the descending of the surface of the material over a different harder surface. Fretting wear is the wear which causes the deduction of material from both the surfaces in contact over an extended period of time. Erosive wear causes wear of the material due to the effect of solid or liquid particles over a short period of time.

10. Deformation that occurs due to stress over a period of time is known as ____________
a) Wear resistance
b) Fatigue
c) Creep
d) Fracture

View Answer

Answer: c [Reason:] Creep is the time-dependent deformation of the material under stress. Wear resistance, fatigue, and fracture deal with deformation under stress without a time factor, i.e. they are time-independent.

Set 5

1. Creep occurs at a temperature above ________
a) 0.16 Tm
b) 0.22 Tm
c) 0.4 Tm
d) 0.91 Tm

View Answer

Answer: c [Reason:] Creep is defined as the permanent deformation of a material due to the application of steady load. It is appreciable only at temperatures above 0.4 Tm.

2. __________ experiences creep at room temperature.
a) Iron
b) Copper
c) Nickel
d) Lead

View Answer

Answer: d [Reason:] Room temperature is about the same as that of the melting point of lead. Therefore, nickel experiences creep at that temperature under its own load. The room temperature of iron and copper is 0.16 Tm and 0.22 Tm respectively, at which creep does not occur.

3. _______ is known as steady-state creep.
a) Primary creep
b) Secondary creep
c) Tertiary creep
d) Quaternary creep

View Answer

Answer: b [Reason:] Creep occurs in three stages known as primary, secondary, and tertiary creep. Secondary creep is also known as steady-state creep since the rate of work and recoveries are equal.

4. Which of the following does not affect creep?
a) Grain size
b) Thermal stability
c) Chemical reactions
d) Crystal structure

View Answer

Answer: d [Reason:] Coarse-grained materials and those having higher thermal stability generally affect creep resistance of a material. The chemical reaction involved and work hardening also influence the creep resistance.

5. The time required for occurrence of creep is known as _________
a) Creep resistance
b) Creep life
c) Creep limit
d) Creep recurrence

View Answer

Answer: b [Reason:] Creep life is defined as the time required for the occurrence of creep fracture in a material under static load. Creep limit is defined as the maximum static stress that will result in creep. Creep resistance is known as the resistance offered by the material over creep.

6. Which of the following will be rendered useless for prevention of creep?
a) Coarse-grained material
b) Strain hardening
c) Precipitation hardening
d) Quenching

View Answer

Answer: d [Reason:] Creep fracture can be prevented by using coarse-grained materials and treatment by strain hardening a precipitation hardening. The material must be free from residual stresses and can also be heat treated.

7. MgO and Al2O3 can be used at high temperature creep resistance due to _________
a) High melting point
b) High oxygen concentration
c) Low density
d) Chemical stability

View Answer

Answer: a [Reason:] Creep starts to occur at a temperature higher than 0.4 Tm. Therefore, high melting point materials like MgO and Al2O3 are used for high-temperature operations.

8. Iron base alloys have melting point around __________
a) 900oC
b) 1500oC
c) 1900oC
d) 2400oC

View Answer

Answer: b [Reason:] The most commonly used high-temperature alloys are iron base, nickel base, and cobalt base alloys. Each of these alloys possesses a high melting point temperature of around 1500oC.

9. Strengthening of iron base, nickel bade, and cobalt base alloys is done by __________
a) Precipitation hardening
b) Grain boundary hardening
c) Dispersion hardening
d) Transformation hardening

View Answer

Answer: c [Reason:] Iron base, nickel base, and cobalt base alloys have creep resistance around a temperature of 0.5 Tm. Their creep resistance can be improved by a heat treatment process known as dispersion hardening.

10. Why can’t cold working be used for strengthening in case of plastic deformation?
a) Recrystallization
b) Thermal instability
c) Lowers tensile strength
d) Introduces coarsening

View Answer

Answer: a [Reason:] At temperatures above 0.4 Tm, recrystallization occurs readily. This results in loss of strength of the cold-worked material. Therefore, for plastic deformation, cold working is generally avoided for creep resistance.