practice_final

practice_final - Materials Science and Engineering 564...

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1/9 Materials Science and Engineering 564 Mechanical behavior and microstructure Winter 2007 Final Exam March 13, 2007 Instructions: Enter your 4-digit course code here for identification: _____________ You have approximately 1:50 to complete this exam. Answer all questions. Write your answers in the space provided. Show all work in order for partial credit to be considered. You may use your two-sided sheet of personal notes, a calculator, and a ruler. The point values for each question are given below. Good luck! 1: __/10 2: __/10 3: __/10 4: __/10 5: __/10 6: __/10 7: __/15 8: __/15 9: __/10 10: __/10 11: __/30 TOTAL: ______/140

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MSE 564 Final Mar. 13, 2007 page 2 / 9pages total 1. Yield strength of a polycrystal (10 points) A polycrystalline metal rod is loaded in simultaneous tension σ xx and torsion σ xy = σ yx . The ratio of applied tensile to shear stress is 2:1. Yield is observed when σ xy reaches 100 MPa. Estimate the yield strength of the material in simple tension. Answer (10 points): tensile yield strength = 2. Response of a polycrystalline metal with nanometer grain size (10 points) State whether the room temperature yield strength and elevated temperature creep rate are expected to increase, decrease, or remain unchanged as grain size is decreased from 50 μ m to 50 nm. For each property, circle the appropriate response and then provide a short explanation that states the explicit dependence on grain size. a. room T yield strength (circle one): increase decrease unchanged Explanation: b. elevated T creep rate (circle one): increase decrease unchanged Explanation:
MSE 564 Final Mar. 13, 2007 page 3 / 9pages total 3. Creep rupture lifetime (10 points) Based on the Larson-Miller plot below, does cutting the stress in half lead to more

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This note was uploaded on 07/17/2008 for the course MSE 564 taught by Professor Anderson during the Winter '08 term at Ohio State.

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practice_final - Materials Science and Engineering 564...

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