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Tuesday, 3 December 2013

Physical metallurgy-Model question paper for B.E/B.Tech



1(a) Distinguish between hexagonal space lattice and HCP crystal. (6 Marks)
(b) Complete solid solubility is not possible in interstitial solid solutions. Explain why. (6 Marks)
(c) Mention some common type of point imperfections. (4 Marks)
(d) Determine the average grain diameter for ASTM grain size number 14. How much change can expect if the ASTM number is 12. (4 Marks)
2(a) Explain why coring occurs to a greater extent in Cu-Sn alloys than in Cu-Zn alloys. (6 Marks)
(b) A binary eutectic freezes at a fixed temperature, whereas in a ternary system with three phase equilibrium, freezing is over a range of temperature. Explain the reason for this. (6 Marks)
(c) Distinguish between hypoeutectoid steels and hypereutectoid steels. (4 Marks)
(d) Calculate the fractions of proeutectoid ferrite, eutectoid ferrite and total ferrite in a 0.2% C steel. (4 Marks)
3(a) What is homogeneous nucleation? Explain. (6 Marks)
(b) Distinguish between normal segregation and inverse segregation. (4 Marks)
(c) Write a note on martensitic transformations. (4 Marks)
(d) What is solute drag effect? Explain. (4 Marks)
4 (a) Explain how T-T-T diagram and C-C-T diagram are determined. (8 Marks)
(b) What is patenting? Explain its relevance in heat treatment process. (4 Marks)
(c) Are post-carburizing heat treatments necessary? Explain. (4 Marks)
(d) Explain why a 0.2% carbon steel carburizes much more easily at 8750C than Armco iron.
(4 Marks)
5(a) Explain the processes slip and twinning. (6 Marks)
(b) Explain how precipitation hardening helps in strengthening metals against yield. (6 Marks)
(c) Explain Griffith criterion. (4 Marks)
(d) The grain size of a mild steel material is increased from ASTM number 8 to 13 by microalloying additions. Determine the increase in yield strength. (4 Marks)
6(a) Write a note on types of corrosion cells. (5 Marks)
(b) Differentiate between noble coatings and sacrificial coatings. (4 Marks)
(c) Mention some characteristics of stress corrosion cracking. (5 Marks)
(d) Calculate the corrosion rate in mm per year, when iron dissolves as ferrous ions at a current density of 0.15 mA/cm2. (4 Marks)
7 (a) Write a note on dual phase steels. (6 Marks)
(b) What are weathering steels? Mention some advantages. (6 Marks)
(c) Explain the role of nickel in increasing the toughness of ferrite materials. (4 Marks)
(d) Explain how maraging steels are used for space research applications. (4 Marks)
8 (a) Mention some properties required for high temperature alloys. (4 Marks)
(b) What is malleable cast iron? Mention some applications. (6 Marks)
(c) Write a note on babbits. (4 Marks)
(d) Comment on the relative weldability of aged hardened aluminium alloys and aluminium alloys that are not heat treated. (6 Marks)

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