Engineering Metallurgy - Dec 2015

Mechanical Engg (Semester 4)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

Solve any one question from Q1 and Q2

1 (a) What do you mean by widmanstaten structure? Explain the factors responsible for it.(4 marks) 1 (b) What is nucleation? What are the types of nucleation mechanisms?(4 marks) 1 (c) Draw a neat labelled Fe-Fe₃C equilibrium diagram.(5 marks) 2 (a) Draw and explain the cooling curve for off eutectic alloy.(4 marks) 2 (b) Write a short note on sulphur printing.(4 marks) 2 (c) How are steels classified on the basis of their carbon percentage? Give one application of each class.(5 marks)

Solve any one question from Q3 and Q4

3 (a) Give classification of surface hardening treatments and explain any one process in detail with suitable example.(6 marks) 3 (b) Is it possible to improve corrosion resistance by adapting proper design and fabrication? If Yes, explain 3 factors in design and fabrication to support your answer.(6 marks) 4 (a) How intergranular corrosion can be prevented? Explain in detail.(6 marks) 4 (b) What is hardenability? Explain any one method of evaluation of hardenability and discuss factors affecting hardenability.(6 marks)

Solve any one question from Q5 and Q6

5 (a) What do you mean by chilled cast iron? Explain the chill test used to find out chill depth for such cast iron.(7 marks) 5 (b) State various factors affecting the microstructure and properties of cast iron, Explain their influence in brief.(6 marks) 6 (a) Compare white cast iron and Malleable cast iron on the basis of microstructure. Method of production, composition, mechanical properties and give one typical application of each.(7 marks) 6 (b) Compare grey cast iron and S.G. iron on the basis of manufacturing method, microstructure, properties and applications.(6 marks)

Write true or false and justify your answer (any four):

7 (a) Alpha brasses can be cold worked.(3 marks) 7 (b) Invar is used in making measuring scales.(3 marks) 7 (c) Bearing are manufactured from homogeneous materials.(3 marks) 7 (d) Addition of zinc in brass is done for changing the colour of brass.(3 marks) 7 (e) Any one-ferrous alloy can be strengthened by precipitation hardening.(3 marks) 8 (a) Give typical composition, important properties and applications of the following (any three):
i) Elinvar
ii) Admiralty brass
iii) Sn-based babbits
Gun metal.(9 marks) 8 (b) Aluminium alloys are widely used in aeronautics and automobile applications. Comment.(3 marks)