53109-mt---materials Technology

NR

Code No: 53109/MT M.Tech. – I Semester Supplementary Examinations, September, 2008 MATERIALS TECHNOLOGY (Common to Advanced Manufacturing Systems/ Design for Manufacturing) Time: 3hours

Max. Marks:60 Answer any FIVE questions All questions carry equal marks ---

1.a) b) 2.a)

b)

What are the different types of strengthening mechanisms? Explain the grain boundary strengthening mechanism? Explain the differences between deformation of perfect crystals and real crystals? An aluminum-4% copper alloy has a yield stress of 600 Mpa, shear modulus of 27.5 Gpa and the burgers vector of the lattice is 0.25nm. Estimate the particle spacing and particle size in this alloy? What do you understand by poly phase mixtures? Explain about the fiber strengthening mechanism.

3.a) b)

Derive Griffith equation for brittle material of thick plates? What is transition temperature? Explain the factors affecting transition temperature?

4.a) b)

What is the effect of temperature on fatigue? A 4340 steel bar is subjected to a fluctuating axial load that varies from a maximum of 330kN tension to a minimum of 110 kN compressions. The mechanical properties of the steel are σ u =1090MPa, σ 0 =1010 Mpa, σ e =510 MPa. Determine the bar diameter to give infinite fatigue life based on a safety factor of 2.5.

5.a)

Determine the working stress at 6000C and 8000C for type 316 stainless steel if the design criterion is a creep strength based on 1 percent extension in 1000hrs. Use factor of safety of 3. If the true stress and true strain curve is given by σ = 1400ε 0.33 , where stress is in MPa, what is the ultimate tensile strength of the material?

b)

Contd…2

Code No: 53109/MT

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6.

Explain the material selection for nuclear applications with the help of any case study.

7.

Write a) b) c)

8.

List out the advanced structural ceramics. Explain their properties and applications. *****

short note on the following: High strength low alloy steels Smart materials Shape memory alloys.