# Calculate the mass fraction of iron carbide in pearlite.

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Subject: English

Materials Science and Engineering

1. Calculate the mass fraction of iron carbide in pearlite.

2. A steel alloy contains 97.5 wt% Fe, 2.0 wt% Mo, and 0.5 wt% C. (a) What is the eutectoid temperature of this alloy? (b) What is the eutectoid composition?

3. Use the figure in page 29 of lecture file 210412 to determine the Avrami equation for the recrystallization of pure copper at 113C.

4. A cylindrical bar of steel 25 mm in diameter is to be quenched in moderately agitated oil. Surface and center hardness must be at least 55 and 50 HRC, respectively. Which of the following alloys will satisfy these requirements: 1040, 5140, 4340, 4140, and 8640?

5.(a) Plot the hardness profile across the diameter of 1060 steel of grain size #2 that is 40 mm in diameter
and is austenitized and quenched in agitated water.

(b) what is the hardness at 5 mm below the surface?

6. A nylon 6,6 has an average molecular weight of 12,000 g/mol. Calculate the average degree of polymerization. The molecular structure for nylon 6,6 can be found in page 15 of lecture file 210426.

7. To polymerize 4,500 g of ethylene mers with H2O2 to become polyethylene having an average degree of polymerization of 50, calculate the mass of H2O2 needed.