cee60-fa08-mt1-Montiero-soln

cee60-fa08-mt1-Montiero-soln - compressive load P. Compute:...

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UNIVERSITY OF CALIFORNIA AT BERKELEY DEPARTMENT OF CEE FALL SEMESTER, 2008 Instructor: P.J. M. Monteiro Name: ____________________ CE 60 – EXAMINATION Please justify all your answers Question 1 1) The net energy curve (E) vs. inter-atomic spacing (r) curves are shown below for three solids A, B and C. Which solid do you expect to have the largest elastic modulus? Explain. Answer: Solid A (higher slope) II) During solidification, how does the degree of undercooling affect the critical nucleus size? Assume homogeneous nucleation. III) Calculate the radius of the largest interstitial void (Rvoid in the figure below) in the BCC α iron lattice. The atomic radius of the iron atom in this lattice is 0.124 nm, and the largest interstitial voids occur at the (¼, ½, 0).
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Question 2 I) Explain what is Poisson’s ratio. If the applied load resulted in elastic deformation without volume change, what is the Poisson ratio? Poisson’s ratio = 0.5 II) A steel rod of original cross section Ao and gage length Lo is loaded with a
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Unformatted text preview: compressive load P. Compute: a) the true and engineering strains. Which one is bigger? True strains b) the true and engineering stresses. Which one is bigger? Engineering stress III) The following engineering stress-strain plot was obtained for a plain-carbon steel. Compute the yield point at a strain offset of 0.2 % (11 points) Answer: 67000 psi Question 3: (38 points) I) A hypoeutectoid plain-carbon steel contains 17% of proeutectoid ferrite at temperature just slightly above 723 C. Calculate the amount of pearlite in the steel at a temperature just slightly below 723 C. (15 points) Answer: 83% II) A hypereutectoid steel contains 96.59% eutectoid ferrite. What is the average carbon content? (15 points) Answer: 0.91% Carbon III) A 1.5%C hypereutectoid plain-carbon steel is slowly cooled from 950 C to a temperature just slightly above 723 C. Calculate the weight percent proeutectoid cementite in this steel. (8 points) Answer: 11.93%...
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cee60-fa08-mt1-Montiero-soln - compressive load P. Compute:...

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