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Solved Test 3 for Mechanical Properties of Structural Materials | MSE 200, Exams of Materials science

North Carolina State University (NCSU)Materials science
Prof. Jagannadham Kasichainula

Material Type: Exam; Professor: Kasichainula; Class: Mechanical Properties of Structural Materials; Subject: Materials Science and Engineering; University: North Carolina State University; Term: Fall 2010;

Typology: Exams

2009/2010

Uploaded on 12/12/2010

rjpalka
rjpalka 🇺🇸

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MAT 200 Test#3, ID Number___________________
This is a closed book test. No notes, books, or information stored in calculator memories
may be used. Cheating will be punished severely. Using a pencil, fill your answers on
the scan sheet after you complete the exam and return the scan sheet along with
your answers to the examination questions.
d______1. A general trend in steels as the carbon content is decreased is to
a. increase the hardness of the alloy
b. decrease the ductility of the alloy
c. increase the yield strength of the alloy
d. none of the above
c______2. Bainite
a. forms during a peritectic reaction
b. is a cubic phase which exists at low temperature
c. contains an extremely fine mixture of Fe3C and ferrite
d. none of the above
d______3. Which is not a mixture of cementite (Fe3C) and ferrite (
a. pearlite b. bainite c. spheroidite d. martensite
d______4. A solid solution such as in the isomorphous Cu-Ni binary is posible when
a. the atoms are different sizes
b. the pure components have different crystal structure
c. the atoms have a large difference in valence
d. none of the above
c______5. A reaction, such as the eutectoid Fe3C will proceed in two
steps:
a. recovery and recrystallization
b. quench and age
c. nucleation and growth
d. melt and crystallize
Q2. Answer the following questions in the phase diagram given below.
1
pf3
pf4
pf5
pf8

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Download Solved Test 3 for Mechanical Properties of Structural Materials | MSE 200 and more Exams Materials science in PDF only on Docsity!

MAT 200 Test#3, ID Number___________________ This is a closed book test. No notes, books, or information stored in calculator memories may be used. Cheating will be punished severely. Using a pencil, fill your answers on the scan sheet after you complete the exam and return the scan sheet along with your answers to the examination questions. d______1. A general trend in steels as the carbon content is decreased is to a. increase the hardness of the alloy b. decrease the ductility of the alloy c. increase the yield strength of the alloy d. none of the above c______2. Bainite a. forms during a peritectic reaction b. is a cubic phase which exists at low temperature c. contains an extremely fine mixture of Fe3C and ferrite d. none of the above d______3. Which is not a mixture of cementite (Fe3C) and ferrite ( a. pearlite b. bainite c. spheroidite d. martensite d______4. A solid solution such as in the isomorphous Cu-Ni binary is posible when a. the atoms are different sizes b. the pure components have different crystal structure c. the atoms have a large difference in valence d. none of the above c______5. A reaction, such as the eutectoid Fe3C will proceed in two steps: a. recovery and recrystallization b. quench and age c. nucleation and growth d. melt and crystallize Q2. Answer the following questions in the phase diagram given below.

  1. The maximum solid solubility of B in A is a. 20% b. 80% c. 50% ( a )
  2. The fraction of  in the eutectic alloy slightly below eutectic temperature is a. 0.5 b. 0.2 c. 40/85 ( a )
  3. In an alloy of 70% B, the proeutectic phase is a.  b.  c. liquid ( b )
  4. The fraction of proeutectic phase in 30% B slightly above eutectic temperature is a. 2/3 b. 1/3 c. none ( a )
  5. The fraction of phase  in the 30 %B alloy slightly below eutectic is a. 5/6 b. 1/6 c. 2/3 ( b )
  6. The fraction of  in the euetctic lamellar structure in the 30% B alloy slightly below eutectic temperature is a. 1/6 b. 0.5 c. 5/6 ( a ) Q 3. In the Fe-C diagram given in the last page, consider an alloy with 0.76 wt% carbon (0.8%) and answer the following questions.
  7. The microsctruture of this alloy below 727oC consists of a. regions of ferrite b. regions of ferrite plus pealrlite c. only pearlite ( c )
  8. The amount of cementite in the 0.8% carbon steel below 727oC is a. 0.8/(6.7) b. (5.1)/(5.9) c. (0.8)/(5.1) ( a )
  9. The composition of ferrite slightly below 727oC is a. 1.8% b. 0.8% c. 0.025% ( c )
  1. Path 1 gives (A) 50% UB and rest martensite (B) Martensite only (C) LB only.... (D) 50% CP and rest martensite ( d )
  2. Path 2 gives (A) 50% UB and rest martensite (B) Martensite only (C) LB only.... (D) 50% CP and rest martensite ( a )
  3. Path 3 gives (A) 50% UB and rest martensite (B) Martensite only (C) LB only.... (D) 50% CP and rest martensite ( b )
  4. Path 4 gives (A) 50% UB and rest martensite (B) Martensite only (C) LB only.... (D) 50% CP and rest martensite ( c ) Q6. From the above TTT diagram with the path of the four different heat treatments identify the heat treatment by matching.
  1. Path 1 is called A. Austempering B. Tempering C. Martempering D. Annealing ( d )
  2. Path 2 is called A. Austempering B. Tempering C. Martempering D. Annealing ( c )
  3. Path 3 is called A. Austempering B. Tempering C. Martempering D. Annealing ( b )
  4. Path 4 is called A. Austempering B. Tempering C. Martempering D. Annealing ( a ) Q7. In the above TTT digram, match the purpose of each heat treatment.
  5. Path 1 is used for A. Stress relieving of cold worked steel B. Hardening a thin section C. Hardening a large section with no cracks D. Hardening of large sections that cannot be quenched ( a )
  6. Path 2 is used for A. Stress relieving of cold worked steel B. Hardening a thin section C. Hardening a large section with no cracks D. Hardening of large sections that cannot be quenched ( c )

c. partially coherent state of precipitates ( b )

  1. Region 2 represents a. as quenched state b. coherent state of precipitates c. partially coherent state of precipitates ( c )
  2. A necessary condition for observing the increase in strength with ageing time is a. solid solubility b. sloping solvus line c. presence of an invariant point ( b ) Q9. Bonus question: Choose the iron-carbon aloy for the applications given.
  3. For rails, A. 4.3% carbon with 2-3%Si and 0.3% Mg and Ce B. 0.4% carbon C. 0.8% carbon D. 1.4% carbon + 1% alloying ( c )
  4. For underground water and sewer pipes, A. 4.3% carbon with 2-3%Si and 0.3% Mg and Ce B. 0.4% carbon C. 0.8% carbon D. 1.4% carbon + 1% alloying ( a )
  5. For I-section beams, A. 4.3% carbon with 2-3%Si and 0.3% Mg and Ce B. 0.4% carbon C. 0.8% carbon D. 1.4% carbon + 1% alloying ( b )
  6. For cutting tools, A. 4.3% carbon with 2-3%Si and 0.3% Mg and Ce B. 0.4% carbon C. 0.8% carbon D. 1.4% carbon + 1% alloying ( d )

Fe-C diagram given below.