JNTU
JNTU B.Tech III MECHANICAL WORKING OF METALS Previous Question Paper (April - 2018 - R15)
Note: This question paper contains two parts A and B. 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 and may have a, b and c as sub questions.
PART - A
Distinguish between open die forging and closed die forging.
Answer
In open die forging, the workpiece is compressed between two flat or simple-shaped dies without constraining the lateral flow of metal. In closed die forging, the metal is shaped within a cavity formed by two or more die halves, which restricts lateral flow and allows for the production of complex, high-precision shapes.
Discuss the difference between streamline dies and flat dies.
Answer
Streamline dies are designed with a curved profile to ensure smooth, continuous metal flow, minimizing friction and redundant work during extrusion or drawing. Flat dies have a simple planar surface, which often leads to dead metal zones, higher friction, and increased shear deformation at the entry and exit points.
What are residual stresses? How are they different from conventional body stresses.
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Compare engineering true stress and engineering true strain at the necking point.
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Explain about buckling.
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Why does a brittle material not have stable crack growth?
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Why are thin sheets are tough than thick sheets?
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Explain the analysis of rolling load and rolling variables.
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What are stretcher strains?
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Differentiate between torque and horsepower.
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PART - B
Discuss briefly about strain at a point.
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Distinguish between Mohrs circle of stress in two dimensions and three dimensions.
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Explain about Mohrs circle of stress in three dimensions.
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Differentiate between Stress at a point and strain at a point.
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Discuss briefly theories of plasticity.
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Compare shear stress and shear strain.
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Draw stress-strain curve of 0.2% C steel and mark the important points in it.
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How does carbon percentage influence flow curve of 0.2 % C steel? Discuss.
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Write explanatory notes on cold working with respect to recovery, recrystallisation, and grain growth.
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What is forging and classify the processes.
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Compare cold working and hot working.
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What is the theory of hot rolling? Explain the conditions for obtaining limiting thickness.
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Explain the reason for designing rolling mills with complex clusters of rolls.
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Write short notes on rolling defects and their remedial measures.
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A steel rod of diameter 10 mm is extruded into a tube of 7.5 mm outer diameter and 5 mm internal diameter. Determine the extrusion ratio.
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Sketch and explain how impact extrusion is done to produce hollow shapes.
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Explain the effect of die angle on the components of the total energy of deformation in wire drawing.
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Write explanatory note on deep drawing processes.
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