JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV SUPER ALLOYS Previous Question Paper (May - 2019 - R15)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
PART - A
What are the properties of super alloys?
Answer
Super alloys exhibit exceptional mechanical strength, resistance to thermal creep deformation, good surface stability, and resistance to corrosion or oxidation at high temperatures.
Why Nickel is main element for high temperature alloys? Justify role of Ni.
Answer
Nickel is the preferred base element because it possesses a stable face-centered cubic (FCC) crystal structure that remains ductile at cryogenic temperatures and maintains high strength at elevated temperatures. Nickel provides excellent solubility for various alloying elements, allowing for the formation of the coherent gamma-prime (Ni3Al) precipitate phase, which is essential for precipitation hardening and creep resistance.
Define lattice misfit?
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Differentiate the diffusion & overlay coatings used for super alloy components?
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What is polygonisation?
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Define the term topologically close packed phases (TCP)? Give an example.
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Give the advantages of single crystal super alloys?
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Explain the various developments in materials for turbine blade applications in gas turbine engines
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List out various forming methods used for super alloys?
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What is sintering? Write the advantages of sintering?
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PART - B
What are different alloying elements chosen for Ni-base super alloys? Explain the role of alloying elements on Ni-base super alloys.
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What are different applications of high temperature alloys?
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Explain the Microstructure of Co-base super alloys in detail.
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Write the classification of Iron-base heat resistant alloys in detail.
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What is the effect of temperature and aging time on gamma prime precipitate phase of Ni-base super alloys and correlate this with the different properties?
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Explain the oxidation of super alloys at higher temperature. What are most effective remedies for preventing oxidation?
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Explain the thermal spray processing method of coating for super alloy components?
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Explain Solid solution strengthening mechanism of super alloys.
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Explain orwan-Bypass mechanism in detail with neat diagram.
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What are various effects of boron and zirconium additions to the super alloys?
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Discuss the effect of increment in service temperature on creep behavior and strength of super alloys.
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Explain the principles and practices of vacuum Arc melting of super alloys in detail with neat diagram
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Explain processing method to develop single crystal turbine blade with neat diagram.
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What kind of failures occurrs, if the turbine blade made is of equiaxed grain structure?
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Explain Hot-Isostatic pressing with neat diagram for production of super alloy components.
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Explain Precipitation hardening heat treating process of heat resistant Fe-base super alloys in detail.
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Are cobalt base super alloys not hardened by aging? Justify the answer
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