Material Science & Metallurgy - Jan 2013

Mechanical Engineering (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. 1 (a) Define atomic packing factor and calculate atomic radius and packing factor for BCC structure (8 marks) 1 (b) With a neat sketch, explain the line dislocation (6 marks) 1 (c) State and explain the Fick's second law of diffusion.(6 marks) 2 (a) With the help of a neat schematic conventional stress diagram for mild steel under tension,explain clearly the behaviour of the material till fracture(6 marks) 2 (b) Explain non-linear elastic properties when a material is subjected to static tension (6 marks) 2 (c) What is work hardening?Explain the reasons for the same(6 marks) 3 (a) Explain with neat figure ductile feature using both stress strain and stages of fracture (8 marks) 3 (b) What is mean by stress relaxation ?Explain with figure(6 marks) 3 (c) With the help of sketch,discuss the different types of stress cycles which bring about fatigue failure(6 marks) 4 (a) Explain with neat sketches the different stages of mechanism of solidification (8 marks) 4 (b) Define solid solution .Explain the substitutional and interstitial solid solution (8 marks) 4 (c) Explain the factor governing the formation of substitutional solid solution(4 marks) 5 (a) Draw and explain the Iron -Iron carbide equilibrium diagram and label all the points and field (10 marks) 5 (b) Construct a phase digram using the following data and label all the fields;
Melting point of Ag =961°C
Melting point of Cu =1083°C ,

Eutectic temperature =780°C
Eutectic composition =28%Cu

Max solubility of Cu in Ag=9% at 780°C
Max. solubility of c in Ag =2%at 0°C

Max. solubility of Cu in Ag =9% at 780°c
Max. solubility of Cu in Ag =0% at 0°C.
Determine the following ;
solidification start and end solid temperature for 30% Ag alloy.
Temperature at which a 15% Cu alloy has 50% liquid phase and 50% solid phase
Percentage composition of liquid and solid phase 20% Ag alloy at 900°C(10 marks) 6 (a) Draw the TTT digram of Austenite for eutectoid steel. Explain the various transmission product of Austenite(8 marks) 6 (b) Discuss the process temperature range range, microstructure of products and application of stress relief annealing(6 marks) 6 (c) Explain with neat sketch induction hardening process(6 marks) 7 (a) Give the composition,structure and their application of
S.G iron
Malleable Iron
Gray cast Iron(8 marks) 7 (b) Name at least four important copper base alloys.Give Composition microstructure and their application (8 marks) 7 (c) Write a note on AL-Si alloys(4 marks) 8 (a) Explain the term composite material with example.State their advantages limitation of composites in practice(8 marks) 8 (b) Using neat sketch ,explain the process of preparation of metal matrix composite using melting and casting method(8 marks) 8 (c) What are FRPs?Give at least four example(4 marks)