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spring03

# spring03 - All questions carry 2 points Formulae are...

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All questions carry 2 points. Formulae are provided below. Formulae: Rss= σ cos f cos l. e=(lf-lo)/lo, e = ln (lf/lo), σ =F/A, σ =F/Ao, σ = σ oexp(-t/tr), tr = tr oexp(Q/kT), KIC= σ f( π c) ½, e'= e o'exp(-Q/kT), η = η o. exp(Q/kT). Q1. An aluminum crystal is loaded along [001] and observed to slip on (111)[01-1]. The applied stress reached a value of G/250 when slip occurred. G is the shear modulus of aluminum. Answer the following questions. 1. The resolved shear stress on the slip system is a. G/250 b. G/612 c. G/1500 2. The critical resolved shear stress is a. G/250 b. G/612 c. G/1500 3. Would you expect to take place on (111){1-10] a. yes b. no c. may be Q2. The following stress-strain curves are obtained by calculation from the same test of a well annealed sample. Answer the following questions. 1. The test is a. compression test b. tensile test c. Hardness test 2. The yield strength of the material is a. close to 10 Ksi b. close to 26 Ksi c.close to 20 ksi 3. The UTS of the alloy is close to a. close to 38 Ksi b. close to 26 Ksi c. close to 20 Ksi 4. The fracture strength of the material is a. close to 38 Ksi b. close to 26 Ksi c. close to 20 Ksi

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5. The total plastic strain is a. close to 0.52 b. close to 0.45 c. close to 0.25 6. The material should be considered as a. brittle b. ductile c. very brittle 7. The material has exhibited a. no work hardening b. work hardening c. elastic-plastic behavior 8. This material is expected to be a. mild steel b. nonferrous alloy or alloy steel c. lead (metal) 9. The ratio of initial cross-sectional area to the final area of cross-section will be a. above 1.5 b. above 1.0 c. below 1.0 10. The engineering strain at necking is close to a. 0.2 b. 0.3 c. 0.5 11. The true strain at necking is close to a. 0.182 b.0.26 c. 0.41 12. The power hardening exponent is expected to be a. 0.182 b.0.26 c. 0.41 Q3. A creep test has given the following results. Test result A is obtained at 400oC and test B is obtained at 600oC. Answer the following questions.
1. Creep life at 400oC is a. above 14000 hrs b. below 14000 hrs c. below 12000 hrs 2. The steady state creep behavior at 400oC is observed in the range

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spring03 - All questions carry 2 points Formulae are...

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