B.TECH/ME/3RD SEM/MECH 2104/2016 B.

TECH/ME/3RD SEM/MECH 2104/2016

(viii) Delta iron occurs at temperature of (b) A tensile stress is to be applied along the long axis of a cylindrical
(a) room temperature (b) above melting point brass rod of 10 mm diameter. Determine the magnitude of the load
(c) between 14000C to15390C (d) between 9100C to 14000C. necessary to produce a 2.4 × 10-3 mm change in diameter assuming
that the deformation is entirely elastic. For brass the value for
(ix) Which of the following constituents of steel is softest and least
Poisson’s ratio is 0.34, and the modulus of elasticity is 97GPa.
strong?
(a) austenite (b) perlite 4 + 8 = 12
(c) ferrite (d) cementite.
7. (a) Mention various factors that affect the mechanical properties of a
(x) The hardness of martensite in a steel is a function of metal.
(a) C content (b) cooling rate
(b) The following observations were made during a tensile test on a mild
(c) Ni content (d) nose location.
steel specimen 40mm in diameter and 200 mm long:
Elongation with 40 KN load (within limit of proportionality)
Group - B
l=0.0304 mm,
2. (a) What do you mean by “Miller Indices”? Explain the procedure for Yield point load = 161 KN,
finding Miller Indices. Maximum load = 242 KN,
Length of specimen at fracture = 249 mm
(b) Obtain the Miller Indices of a plane whose intercepts are ‘a’, ‘b/2’
Determine (a) young’s modulus of elasticity (b) yield point stress
and 3c on x, y and z axes respectively in a simple cubic unit cell.
(c) ultimate stress and (d) percentage elongation.
6 + 6 = 12 6 + 6 = 12
3. (a) What do you understand by the term "point defects"? Name their Group - E
types with the corresponding sketches.
8. (a) Define polymerization. Differentiate between the two different types
(b) Mention the differences between the slip and twinning mechanism of polymerization.
for plastic deformation of metals.
6 + 6 = 12 (b) What are the general properties to be considered while polymeric
materials are to be used?
Group - C 6 + 6 = 12
4. (a) Define and explain Annealing process and state its objectives. 9. (a) Define composite. What are the differences between alloy and
(b) What are the characteristic properties of tool steel. composite?
6 + 6 = 12 (b) How corrosion can be prevented?
6 + 6 = 12
5. (a) Write short notes on perlite, ledeburite and cementite.
(b) Name any two ferrous alloys mentioning their compositions,
properties and applications.
6 + 6 = 12

Group - D
6. (a) Define fatigue and creep.

MECH 2104 2 MECH 2104 3

 B.TECH/ME/3RD SEM/MECH 2104/2016
ENGINEERING MATERIALS
(MECH 2104)

Time Allotted : 3 hrs Full Marks : 70

Figures out of the right margin indicate full marks.
Candidates are required to answer Group A and
any 5 (five) from Group B to E, taking at least one from each group.
Candidates are required to give answer in their own words as far as
practicable.

Group – A
(Multiple Choice Type Questions)

1. Choose the correct alternative for the following: 10 × 1 = 10

(i) The atomic diameter of an FCC crystal (lattice parameter “a") is
(a) a2 /2 (b) a2/4 (c) a3/4 (d) a/2.
(ii) Strain hardening improves
(a) static tensile strength (b) steady state creep rate
(c) fatigue life (d) none of these.
(iii) Gibbs phase rule for condensed state reaction under constant
pressure is
(a) F+P = C+2 (b) F+C = P+2
(c) F+P = C+1 (d) F+1 = C+P.
(iv) If the radius of an atom in a simple cube crystal is ‘r’, the body
diagonal of the unit cell is
(a) r3 (b) 2r3 (c) 4r/3 (d) 3r/4.
(v) Thermal expansion of materials arises from
(a) strong bonds (b) weak bonds
(c) thermal vibrations (d) asymmetry of potential energy.
(vi) Hydrogen bonds are stronger than
(a) vander waals bonds (b) metallic bonds
(c) ionic bonds (d) covalent bonds.
(vii) The packing efficiency of a simple cubic crystal with an interstitial
atom exactly fitting at the body centre is
(a) 0.52 (b) 0.68 (c) 0.73 (d) 0.91.
MECH 2104 1