JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III WELDING METALLURGY Previous Question Paper (May - 2019 - R16)
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
Write the principle of submerged arc welding.
Answer
In Submerged Arc Welding (SAW), the electric arc is generated between a continuously fed bare consumable electrode and the workpiece. The arc, the molten weld pool, and the surrounding base metal are completely submerged under a blanket of granular, fusible flux. This flux protects the molten metal from atmospheric contamination, acts as a deoxidizer, and influences the weld metal composition.
Draw the gas welding torch and label it.
Answer
A gas welding torch consists of several key components designed to mix oxygen and fuel gas in controlled proportions. The main parts include:
- Oxygen inlet valve: Controls the flow rate of oxygen.
- Fuel gas inlet valve: Controls the flow rate of the fuel gas (e.g., acetylene).
- Gas mixing chamber: Where the two gases are thoroughly blended before combustion.
- Torch handle: The main body gripped by the operator.
- Welding tip/nozzle: The orifice where the gas mixture exits and the flame is ignited.
The assembly functions by feeding gases through the inlet valves into the mixing chamber, from which the mixed gas travels through the torch body to the tip to produce a stable welding flame.
What are the types of explosives used in explosive welding?
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How plasma is generated in PAW?
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What is weldability?
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Give the importance of post weld heat treatments.
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Define the term dilution in welding of dissimilar metals.
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List the welding techniques employed in joining ceramics.
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What is HAZ cracking?
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What are the advantages of dye penetration test for weldments?
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Part B
Write about GTAW process in detail.
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Give the advantages and limitations of MMAW over GTAW.
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Explain the process of SAW? Give its applications and limitations.
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What is soldering and brazing? Explain the similarities and differences between soldering and brazing.
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What is transferred and non-transferred plasma arc welding? Explain in detail.
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Briefly describe the principle of electron beam welding. Explain the process parameters and give its limitations.
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What is the principle of friction stir welding? How is it different from fusion welding processes? Explain.
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Write about the LASER welding process in detail. Give some applications of LASER welding process.
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Describe different zones in HAZ with the help of a neat sketch.
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What are different types of cast irons? What are the problems associated with cast irons while welding? Explain.
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Write down the classification of Aluminium alloys. Discuss any two problems associated with welding of aluminium alloys.
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Explain about Schaffler and Delong diagrams.
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What is adhesive joining? How is it useful in dissimilar metal joining? Explain.
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What are the challenges in dissimilar metal welding? Explain in detail.
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Explain about the significance of ultrasonic welding in dissimilar metal joining.
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What is friction riveting? Explain in detail. How it is useful in dissimilar metal welding?
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What is radiography? Explain the determination of welding defects by radiography.
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What are different types of welding defects? Give their causes.
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What is the importance of quality testing of a weld joint? Discuss in detail.
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What is hot cracking? Give its causes and suggest suitable remedies.
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