Exam Details
| Subject | metallurgy and materials engineering(mc, mp, ma, me, pe) | |
| Paper | ||
| Exam / Course | b.tech | |
| Department | ||
| Organization | Government Degree College, Kamalpur | |
| Position | ||
| Exam Date | April, 2018 | |
| City, State | tripura, dhalai |
Question Paper
E E4850 Pages: 2
Page 1 of 2
Reg
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
THIRD/FOURTH SEMESTER B.TECH DEGREE EXAMINATION, APRIL 2018
Course Code: ME210
Course Name: METALLURGY AND MATERIALS ENGINEERING
MP, MA, ME, PE)
Max. Marks: 100 Duration: 3 Hours
PART A
Answer any three full questions, each carries 10 marks. Marks
1 Explain with neat sketches the mechanism of dislocation and twinning as related
to plastic deformation.
What are Miller Indices? Sketch planes on a cubic unit cell.
2 Define critically resolved shear stress.
A single metal crystal is oriented such that the normal to the slip plane and the
slip direction are at angles of 43.1° and 47.9°, respectively, with the tensile axis.
If the critical resolved shear stress is 20.7 MPa, will an applied stress of 45 MPa
cause the single crystal to yield? If not, what stress will benecessary?
Is iron an allotropic metal? Explain.
3 How are yield strength and grain size of a crystal related?
Yield strength of mild steel with an average grain size of 0.05mm is 138MPa and
with a grain size of 0.007mm is 276MPa. What will be the average grain size for
the same steel for yield strength of 207MPa?
What is the significance of Burgers vector and Frank Read source in dislocation?
4 Explain the Fick's laws of diffusion.
An iron plate is exposed to a carburising atmosphere on one side and a
decarburising atmosphere on other side at 720ºC. If a steady state condition is
achieved, calculate the diffusion flux of carbon through the plate if the
concentrations of carbon at positions of 6mm and 11mm beneath the carburising
surface are 1.22 kg/m3 and 0.82 kg/m3 respectively. Assume a diffusion
coefficient of 3.2 x 10 11 m2/s at this temperature.
PART B
Answer any three full questions, each carries 10 marks.
5 Sketch and label the Iron-Carbon equilibrium diagram and explain the three
equilibrium reactions in it.
Copper (melting point 1083ºC) and silver (melting point 961ºC) form an alloy
system which has partial solubility in the solid state. The mutual solubility of
silver in copper is 7.9% and that of copper in silver is 8.8% at a eutectic
temperature of 779ºC. The eutectic alloy has 71.9% silver. Sketch and label the
phase diagram for Cu-Ag alloy system.
6 Most cast alloys are reheated to a temperature below solidus after the
solidification is completed. Why?
What is the significance of critical cooling rate for an iron-carbon alloy system?
E E4850 Pages: 2
Page 2 of 2
Differentiate between martempering and austempering from the process point of
view and the final microstructure point of view.
7 What is work hardening? What is the effect of work hardening on mechanical
properties of a metal?
Explain the various stages and changes in properties when a severely cold
worked metal is annealed at successive high temperatures.
8 What is the fundamental difference between steel and cast iron?
What are the different types of cast iron? How do they differ from each other?
Compare the structure, properties and uses of any two types of cast iron.
PART C
Answer any four full questions, each carries 10 marks.
9 Define endurance limit and fatigue strength reduction factor.
Usually there is a poor correlation between the fatigue strength obtained from lab
tests and the actual service failure. Why?
10 What are the various stages in fatigue failure?
What is ductile to brittle transition? Which material property is of importance in
this phenomenon? Explain with the help of a relevant graph.
11 How is the discrepancy between the fracture strength of a real material and its
theoretical value explained by Griffith's crack theory?
A sample of glass has a crack of length 4μm. Young's modulus of glass is
70GN/m2 and specific surface energy is 1J/m2. Find its fracture strength and
compare it with the Young's Modulus.
12 How does creep differ from fatigue? Sketch a typical creep curve and explain it.
Write a note on creep resistant materials.
13 What is super plasticity? What is the importance of strain rate sensitivity in this
phenomenon?
What is a composite material? What are the roles played by matrix phase and
fiber phase in a composite?
14
Quoting examples, explain the following
Super alloys
ii) Smart materials
iii) Ceramic materials
Page 1 of 2
Reg
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
THIRD/FOURTH SEMESTER B.TECH DEGREE EXAMINATION, APRIL 2018
Course Code: ME210
Course Name: METALLURGY AND MATERIALS ENGINEERING
MP, MA, ME, PE)
Max. Marks: 100 Duration: 3 Hours
PART A
Answer any three full questions, each carries 10 marks. Marks
1 Explain with neat sketches the mechanism of dislocation and twinning as related
to plastic deformation.
What are Miller Indices? Sketch planes on a cubic unit cell.
2 Define critically resolved shear stress.
A single metal crystal is oriented such that the normal to the slip plane and the
slip direction are at angles of 43.1° and 47.9°, respectively, with the tensile axis.
If the critical resolved shear stress is 20.7 MPa, will an applied stress of 45 MPa
cause the single crystal to yield? If not, what stress will benecessary?
Is iron an allotropic metal? Explain.
3 How are yield strength and grain size of a crystal related?
Yield strength of mild steel with an average grain size of 0.05mm is 138MPa and
with a grain size of 0.007mm is 276MPa. What will be the average grain size for
the same steel for yield strength of 207MPa?
What is the significance of Burgers vector and Frank Read source in dislocation?
4 Explain the Fick's laws of diffusion.
An iron plate is exposed to a carburising atmosphere on one side and a
decarburising atmosphere on other side at 720ºC. If a steady state condition is
achieved, calculate the diffusion flux of carbon through the plate if the
concentrations of carbon at positions of 6mm and 11mm beneath the carburising
surface are 1.22 kg/m3 and 0.82 kg/m3 respectively. Assume a diffusion
coefficient of 3.2 x 10 11 m2/s at this temperature.
PART B
Answer any three full questions, each carries 10 marks.
5 Sketch and label the Iron-Carbon equilibrium diagram and explain the three
equilibrium reactions in it.
Copper (melting point 1083ºC) and silver (melting point 961ºC) form an alloy
system which has partial solubility in the solid state. The mutual solubility of
silver in copper is 7.9% and that of copper in silver is 8.8% at a eutectic
temperature of 779ºC. The eutectic alloy has 71.9% silver. Sketch and label the
phase diagram for Cu-Ag alloy system.
6 Most cast alloys are reheated to a temperature below solidus after the
solidification is completed. Why?
What is the significance of critical cooling rate for an iron-carbon alloy system?
E E4850 Pages: 2
Page 2 of 2
Differentiate between martempering and austempering from the process point of
view and the final microstructure point of view.
7 What is work hardening? What is the effect of work hardening on mechanical
properties of a metal?
Explain the various stages and changes in properties when a severely cold
worked metal is annealed at successive high temperatures.
8 What is the fundamental difference between steel and cast iron?
What are the different types of cast iron? How do they differ from each other?
Compare the structure, properties and uses of any two types of cast iron.
PART C
Answer any four full questions, each carries 10 marks.
9 Define endurance limit and fatigue strength reduction factor.
Usually there is a poor correlation between the fatigue strength obtained from lab
tests and the actual service failure. Why?
10 What are the various stages in fatigue failure?
What is ductile to brittle transition? Which material property is of importance in
this phenomenon? Explain with the help of a relevant graph.
11 How is the discrepancy between the fracture strength of a real material and its
theoretical value explained by Griffith's crack theory?
A sample of glass has a crack of length 4μm. Young's modulus of glass is
70GN/m2 and specific surface energy is 1J/m2. Find its fracture strength and
compare it with the Young's Modulus.
12 How does creep differ from fatigue? Sketch a typical creep curve and explain it.
Write a note on creep resistant materials.
13 What is super plasticity? What is the importance of strain rate sensitivity in this
phenomenon?
What is a composite material? What are the roles played by matrix phase and
fiber phase in a composite?
14
Quoting examples, explain the following
Super alloys
ii) Smart materials
iii) Ceramic materials
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