Thapar University 2006 B.E Mechanical Engineering Industrial Metullargy
Thapar Institute of Engineering & Technology
B.Tech Mechanical Engineering (3rd Year)
Final Term exam
ME039 (Industrial Metullargy & Materials)
Thapar Institute of Engineering and Technology, Patiala
End Semester Examination, December, 2006 Characterization and Testing of Materials (MS-102)
Time : 3 hour Marks : 36
Attempt five questions in all. Question No. 1 is compulsory.
Attempt all parts of a question together.
Q1 Is the following Statements are true or false. No marks without explanation in 50-100 words.
(a) Higher the frequency of ultrasonic, higher is the sensitivity of UFD.
(b) Color metallograph can provide more information about the surface characteristics.
(c) Surface defects like seams can be located by Penetrant method.
(d) Visual Testing can give the information about the internal composition of the materials
(4x2)
Q2
(a) What is Differential Interference Contrast (DIC) Optical Microscopy? Discuss its important feature.
(b) How the resolution of an optical microscope varies with wavelength of light used?
(c) Discuss the various factors that are required to be considered for selection of material for aerospace applications.
(3.2.2)
(a) Show that cross-sectional information of particle can be calculated from the total scattered flux of light.
(b) Gas adsorption method can be used to calculate pore size of the compacted powders. How?
(c) Discuss the two applications of Differential Thermal Analysis technique.
(3.2.2)
Q4
(a) What are the effect of fatigue on the properties of the materials? Describe the fatigue limit and its criticality in aeroplane parts.
(b) What is Torsion testing? How it can be performed on axel or main shaft of an automobile.
(c) How the Impact Strength of a material varies with the temperature?
(a) How one can use Ultrasonic Flaw Detector to find size and position of crack in a metallic specimen?
(b) Longitudinal waves are setup in a quartz plate. The fundamental frequency of vibration is given by N = (2.87X105/1), where N is in Hz and t is the thickness of the plate in cm. Compute the (a) Youngs modulus of the quartz plate, (b) the thickness of the plate required for a frequency of 1.2 MHz. The density of quartz is 2.66 gm/cm3.
(c) How Tempilstiks can be used for thermal testing of the materials?
(3,2,2)
Q6
(a) How Thermogravimetric Analysis is carried out for polymeric materials?
(b) The particle size distribution of a powder is as follows:
|
Mean Size(nm) |
4 |
6 |
9 |
12 |
18 |
25 |
|
Number of particles: |
10 |
16 |
20 |
25 |
15 |
7 |
Calculate the arithmetic, geometric and harmonic mean sizes. Also draw histogram for the above distribution.
(3,3,1)
(c) What are the limitations of the Radiograph?
THAPAR INSTITUTE OF ENGINEERING AND TECHNOLOGY MECHANICAL ENGINEERING DEPARTMENT B.E Illrd YEAR (MECHANICAL)
ME-039 INDUSTRIAL METALLURGY AND MATERIALS MARKS: 60 TIME: 3 Hrs
Note: Attempt five questions in all. Qfr. is compulsory. All questions carry equal marks.
Answers should be brief & to the point. Attempt all parts of a question at one place.
Draw neat and labeled diagrams wherever required.
Evaluated answer sheets can be seen in the office of teacher incharge on 16.12.06 between 10.00-ll.a.m.
QL
a) What is the basic difference in the case hardening treatment given to low carbon steels and that given to medium carbon steels. Why does such a difference exist?
b) What are the three basic reasons for carrying out carburizing and other related processes only at high temperatures? What are the drawbacks of making such temperatures exceptionally high?
c) What is temper embrittlement? Explain the conditions under which it occurs and the various measures to eliminate it?
d) State the Harris equation? State its significance. For which steels is this equation applicable? t
(3X4)
Q2.
a) Surface heat treatments come into picture where conventional treatments cant be used. Discuss.
b) Explain the role of activators with an example in case of pack carburizing?
c) Discuss the steps involved in isothermal annealing.
d) What is fourth stage tempering? What type of microstructure and
characteristics are obtained in the steel after receiving this treatment?
(3X4)
Q3.
a) Discuss what is a CCT diagram? Draw this labeled diagram for eutectoid steel. Bring out the main points of difference between a CCT diagram and the corresponding TTT diagram for the eutectoid steel?
b) What is Widmanstattan structure? Under what conditions does it get formed? What type of heat treatment can be given to eliminate it?
c) What are the benefits derived by normalizing hypereutectoid steel rather than full annealihg it? Under what conditions normalizing can not eliminate full annealing?
d) Describe with an example the difference between hardness and hardenability.
(3X4)
a) What is the reason behind the high hardness of martensite? On what factors does the Ms temperature depend? Which alloying elements can increase this temperature?
b) For a eutectoid steel, below the lower critical temperature, as the transformation temperature is decreased, the incubation period first decreases up to the knee and then starts increasing. Why?
c) Draw a heat labeled Iron-Iron Carbide diagram? Mark all the critical temperature lines and also the invariant reaction points on it? Is this diagram a true equilibrium diagram? Explain.
d) Why steels are generally rolled and forged between 800-1000C temperature range? (3X4)
a) Slate and explain the Gibbs rule? What is the significance of this phase rule?
b) How do the phases affect the properties of a metallic system? Explain with an example.
c) What is meant by the term alloy? With the help of a line diagram, show the metallurgical classification of binary alloys.
d) What are the factors on which coring depends? What are the consequences of this defect when present in steel?
(3X4)
a) What is meant by the term components of a system? Explain with examples.
b) What are type II systems? Why are these called eutectic systems? With the help of thermal analysis technique, obtain the Pb-Sn equilibrium diagram.
c) What are the main points of difference between inherently fine and inherently coarse grained steels?
d) What do the A0,A2 and ACfn lines signify?
(3X4)
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| Earning: Approval pending. |
