JNTU
JNTU B.Tech III MECHANICAL METALLURGY Previous Question Paper (November/December - 2017 - 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, c as sub questions.
Part A
Answer all questions.
What are the defects that occur in crystalline materials?
Answer
Defects in crystalline materials are classified by their dimensionality: point defects (vacancies, interstitials, impurities), line defects (dislocations), planar defects (grain boundaries, stacking faults, twin boundaries), and volume defects (voids, inclusions, precipitates).
Difference between slip and twinning.
Answer
Slip involves the movement of dislocations along specific crystallographic planes and directions, resulting in a permanent displacement where the crystal lattice orientation remains unchanged. Twinning involves a shear displacement where a portion of the crystal lattice is reoriented into a mirror image of the parent crystal across a twin plane.
What is meant by notch sensitivity?
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Differentiate between ductile and brittle fracture.
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Define resilience of material.
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What is the effect of temperature on strain rate?
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Define low cycle fatigue.
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What is the effect of material size on the fatigue?
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What are the advantages of transient creep?
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What are the limitations of rupture test?
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Part B
Define Dislocation. Differentiate between Edge and screw dislocation.
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Explain the critical resolved shear stress. What are it uses?
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Explain the Frank read sources of dislocations with neat sketch.
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What do you mean by Burger’s vector? Explain its role in identifying dislocations in a material.
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What are different Hardness tests? Compare Rockwell Hardness test and Brinell Hardness test.
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Write short notes on Shore and Poldi hardness method.
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Describe Advantages and limitations of following hardness tests:
a) Vickers Hardness Testing
b) Micro hardness testing
c) Rockwell Hardness Testing.
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What are different Mechanical tests? Give comparison of true stress-strain curve and engineering stress-strain curve.
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What are different types of Impact test? Briefly explain advantages and disadvantages of each test.
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Which tests is used to measure toughness? Explain any one method.
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Explain the procedure of tensile testing in brief.
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What do you mean by S-N curve? Differentiate between ferrous alloys and non ferrous alloys with reference to their respective S-N curves.
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Define high cycle fatigue. What are its applications?
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What is meant by fatigue failure? Write a note on fatigue Mechanisms in metals.
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What are the factors influence the fatigue failure? Explain.
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Explain with neat sketch the mechanism of creep deformation in metals. And write its advantages and applications for each.
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Define creep. Draw a typical creep curve and explain the various stages in creep.
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Briefly explain the various effects metallurgical variables on creep.
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