Tuesday, September 01, 2015
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Roll No………
Total No. of
Questions: 08
M.TECH
(Sem.-1st)
WELDING
TECHNOLOGY
Subject
Code: PE-504
Paper
ID: [E0444]
Time: 3 Hrs. Max.
Marks: 100
Instructions to Candidate:-
Note: Answers 5 (Five)
questions out of 8 (Eight) questions.
Each question carries 20 (twenty) marks.
1.
(i) How welding processes are
classified? What is weld ability? Explain.
(ii)
Discuss the principle of resistance welding with the help of weld thermal
cycle.
(iii)
State and explain the solidification mechanism and microstrural products in
welding metal. Give schematic illustration of micro-structure during
solidification of weld zone.
5+5+10=20
2.
(i) State and explain the mechanism of
are initiation during are welding. Give schematic diagram of are welding on a
large plate showing direction of welding, inclination angle of electrode and
position of spark in support of your answer.
(ii)
Deduce an expression for temperature distribution in the are when a semi
infinite plate is welding.
(iii)
Define are efficiency. Discuss the electrical characteristics of an arc.
8+7+5=20
3.
(i) What is heat affected zone(HAZ)?
Explain with a schematic diagram showing subdivisions of HAZ for low carbon
steels welds and their corresponding temperature ranges.
(ii)
How coatings of electrodes for SMAW are classified? Explain with example.
(iii)
State and explain the effect of
electrode coatings on welding
performance characteristics. State the roles of flux ingredients and
shielding gases. Give examples in support of your answer.
8+4+(4+4)=20
4.
(i) Explain the working principle of
GMAW process. Give a simple sketch of
this process.
(ii)
Explain submerged are welding process with suitable sketch. What are the fluxes used in submerged welding
process?
(iii)
Explain electro slag welding process with a suitable sketch. What are the
fluxes used in submerged welding process with suitable sketch. Write its industrial applications.
6+7+7=20
5.
(i)
State and explain the basic characteristics of power sources for various
are welding processes.
(ii)
Define and explain the significance of
the following terms
(a) Duty
cycle, (b) DC rectifier, (c) thyristor controlled rectifier.
7+6+7=20
6.
(i)
Write the name of the different
types of metal transfer during welding. State and explain the mechanism of
metal transfer for each case separately.
(ii)
State and explain the effect of polarity on metal transfer and melting rate.
12+8=20
7.
(i) State the basic theory and explain
the mechanism of solid state welding. Give examples for solid state welding.
(ii)
What is diffusion welding? Explain with a suitable sketch.
(iii)
Explain ultrasonic welding. Give simple sketch for this welding process in
support of your answer.
9+5+6=20
8.
Write short notes on the followings:
(i)
High energy rate welding.
(ii)
Welding using radiation energy.
(iii)
Effect of alloying elements on welding
of ferrous metals.
(iv)
Friction welding.
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