Material Science & Metallurgy - Jan 2014

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) Sketch the unit cell of a HCP crystal structure. Calculate the number of atoms per unit cell.Derive an expression for the density of atomic packing.(Given C=1.6339(8 marks) 1 (b) Explain different types of mechanics of diffusion in solids(8 marks) 1 (c) Aluminium has a FCC structure and an atomic radius of 0.143mm.Calculate volume of its unit cell in cubic meters (4 marks) 2 (a) Define engineering stress and strain true stress strain.find out the relationship between true and engineering strain(8 marks) 2 (b) A steel rod of 10mm diameter and1.5 mm length is subjected to an axial tensile load of 1kN. Determine <be>stress
Strain
strain
Elongation. Take modules of elasticity of steel=205×10⁶kN/m²</be>(6 marks) 2 (c) Differentiate between slip and twinning deformation in materials (6 marks) 3 (a) Define creep with a typical creep curves .Explain different stages of creep(6 marks) 3 (b) Sketches the basis modes of fracture .list the difference between them(6 marks) 3 (c) What is fatigue?Draw the SN curves for steel and aluminium alloys(8 marks) 4 (a) Explain the homogeneous nucleation. Discuss the significance of critical radius of the nuclei(8 marks) 4 (b) Define solid solution .and explain the different type of solid solution(6 marks) 4 (c) State the Gibb's phase rule and explain with a simple example(6 marks) 5 (a) Draw the Iron-carbon equilibrium diagram and label all the field.Write the different invariation reaction(10 marks) 5 (b) Explain the step to construct TTT digram Draw a sketch of a TTT diagram label all the fields for an eutectoid steel(10 marks) 6 (a) Define the process of heat treatment and classify the various heat treatment processes(8 marks) 6 (b) Explain carburizing with a neat sketch(6 marks) 6 (c) Define hardenability of a material and list the factors affecting hardenability.(6 marks) 7 (a) Briefly describe the composition, properties and application of medium and high carbon steel .(8 marks) 7 (b) Briefly describe the composition, properties and application of grey cast iron(6 marks) 7 (c) Discuss AIST-SAE designation of steel with example (6 marks) 8 (a) What is a composite material ?how is it classified ?Explain briefly (10 marks) 8 (b) With a neat sketch,explain the hand lay up laminating process(10 marks)