Str - Final Exam (2007).pdf

8/10/2019 Str - Final Exam (2007).pdf

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ENGR 2220U Structure and Properties of Materials

Final Examination: Fall 2007

Part 2: Duration - 120 Minutes

Instructor: Ghaus Rizvi

DO NOT OPEN THIS BOOKLET UNTIL TOLD TO DO SOImportant: If you have your laptops, do not leave unattended. You can keep

them under your desk.

Instructions:

1. Fill out your name and ID on the exam booklet2. The exam is closed book, closed laptops and closed notes. Calculators and one A4

sheet with hand written notes on both sides is allowed

3. Write clearly; you should not expect marks for something that cannot be read

4. Part 2 will be marked out of 80. There are 8 questions and they carry differentmarks. Allocate your time accordingly

5. Brief answers are preferable

6. Figures in parentheses indicate the marks


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Q7. The isothermal transformation diagram of an alloy is shown below. (17)

a) Is it a eutectoid alloy, hypo-eutectoid alloy or hyper-eutectoid alloy? (3)

b) What will be the microstructures formed if the following heat treatments areperformed.

i) Suddenly cooled to 580C and held at that temperature for a very very

long time. (4)ii) Suddenly cooled to 600C and held at that temperature for 1 second then

suddenly cooled down to 300C and held there for 1000 seconds and then

quenched suddenly to room temperature. (4)c) What heat treatment will you impart if the desired structure is 50% fine pearlite

and 50 Martensite (3)

d) How will you produce a spheroidite structure in this alloy? (3)


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Q8. The continuous cooling characteristics of an alloy are shown below. (15)

a) Is it a eutectoid alloy, hypo-eutectoid alloy or hyper-eutectoid alloy? (3)

b) Write down the microstructures formed, when it is cooled at the following rates?

i) 0.01C/s; ii) 10C/s; iii) 0.2C/s (9)c) What should be the cooling rate if the desired structure is proeutectoid ferrite and

fine pearlite? (3)

Documents

Str - Final Exam (2007).pdf