Material Technology - May 2012

Mechanical Engineering (Semester 4)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1 (a) Discuss the Normalizing heat treatment of Steel.(10 marks) 1 (b) Draw a neat iron-iron carbide equilibrium diagram indicating all important temperature, phases and composition. Explain the slow cooling of an alloy containing 1.2% C Steel, when cooled from 1600°C to room temperature. Draw microstructure at each phase and calculate phases in the alloy at various points by lever rule from liquid state to room temperature.(10 marks) 2 (a) What is work hardening? Explain the various stages of work hardening in detail.(10 marks) 2 (b) What is retained austenite? Explain in detail the tempering process used to eliminate retained austenite.(10 marks) 3 (a) Explain Slip mechanism of plastic deformation. What is Critical Resolved Shear Stress? Derive its expression for deformation by slip. (10 marks) 3 (b) What is Diffusion Coating? Discuss principle, process, chemical reaction, metallization process, advantages, disadvantages and applications of Calorizing. (10 marks) 4 (a) Define Fracture and give a brief classification of fracture. State Griffith's theory of brittle fracture and derive Griffith's equation.(10 marks) 4 (b) Explain in detail the Nitriding heat treatment process.(10 marks) 5 (a) Define Fatigue failure. Give examples of components prone to fatigue failure. Explain the mechanism of fatigue failure. Also discuss the various theories proposed for fatigue failure.(10 marks) 5 (b) Draw a neat and labeled microstructure of White Cast Iron, Grey Cast Iron, Nodular Cast Iron Low Carbon Steel and Eutectoid Steel. (10 marks) 6 (a) Define Creep. Draw Classical Creep Curve. Explain each stage in details. Discuss the development of creep resisting alloys.(10 marks) 6 (b) Give classification of alloying elements. Explain the effect of alloying elements on phase transformation temperatures in Iron, Iron-Carbide diagram. (10 marks)

Write short notes on any four:-

7 (a) Annealing of cold worked metals. (5 marks) 7 (b) Jominy End Quench Test.(5 marks) 7 (c) Age Hardening.(5 marks) 7 (d) Differentiate between Edge Dislocation and Screw Dislocation. (5 marks) 7 (e) Properties of tools steels.(5 marks) 7 (f) The Solid Solution.(5 marks)