VTU Previous Year Question Papers BE ME Third Semester
Materials Science and Metallurgy December 2011
Note: Answer any FIVE full questions, selecting atleast TWO questions from each part.
1 a. Define unit cell, coordination number, vacancy and grain boundary.
b. Draw a neat sketch of a BCC unit cell. Derive the relation between lattice parameters and atomic radius for the BCC unit cell. Calculate its atomic packing factor.
c. Explain edge dislocation, with the help of a neat sketch.
d. Explain briefly the vacancy mechanism of diffusion.
2 a. Define engineering stress and true stress. Derive the relation between the two.
b. A tensile specimen of 10mm diameter and 100mm gauge length is subjected to a tensile test. If its diameter is reduced to 8mm by applying a load of 1500N, what is its final length? Also determine engineering stress, engineering strain, true stress and true strain.
c. Explain Vickers hardness testing, in brief.
d. When a 3000 kg load is applied through a 10mm diameter ball in a Brinell test on steel, an indentation of 3.1 mm is produced. Determine the BHN of the metal.
3 a. Sketch the basic modes of fracture. List the differences between them.
b. Explain with the help of a sketch, the fatigue behaviour of metals. State any three methods to improve fatigue resistance.
c. With the help of a neat sketch, explain the different stages in a creep curve. Give two examples for creep resistant materials.
4 a. State Hume – Rothery rules that govern the formation of solid solutions.
b. Draw neatly labeled sketches of eutectic phase diagrams for a binary system with i) no solid solubility and ii) partial solid solubility.
c. Describe the phase rule and lever rule in brief.
d. A binary alloy system contains two solid phases a and p at a particular temperature. The compositions of a and P are A – 5% B and A – 95% B respectively. Calculate the amount of a and p in i) A- 40% B alloy and ii) A – 70% B alloy at that temperature.
5 a. Draw a neat labeled iron – carbon phase diagram. Write the three invariant reactions taking place in the system.
b. Draw the schematic microstructures of slowly cooled eutectoid steel and hypo – eutectoid Steel.
c. Briefly explain the TTT diagram for eutectoid steel.
6 a. Compare annealing and normalizing heat treatments adopted for steels.
b. Explain carburizing and flame hardening, in brief.
c. Define hardenability. Explain with a neat sketch, the Jominy end quench test of determining the hardenability of steels.
7 a. Briefly describe the composition, properties and applications of medium and high carbon steels.
b. State the properties and applications of gray cast iron.
c. Write a note on brasses.
8 a. Define corrosion. State its effects.
Briefly explain the mechanism of corrosion.
c. Write a note on passivity.
d. List various methods of corrosion prevention. Explain cathodic protection with examples.