Download 20 True False Questions Matli-Science and Engineering | MSE 250 and more Quizzes Materials science in PDF only on Docsity! MSE 250 Quiz 4 (Solution) NAME________________ Summer 2012 PID ________________ Lab time: Tu Th True or false: (circle the correct answer) Correct answer is in RED 1. Prior elastic deformation in metals can cause the value of yield strength to increase. T F 2. It is possible to read‐off the strain hardening exponent from the engineering stress‐strain curve. T F 3. Strain hardening increases the ductility of materials. T F 4. Critical stress needed for failure decreases with increases in the flaw size. T F 5. Critical stress needed for failure decreases with increases in the radius of curvature at the crack tip. T F 6. For brittle materials, only one single crack with length greater than the critical flaw size is needed for failure. T F 7. Crystallography slip can occur during elastic deformation. T F 8. In fatigue, longer cracks grow faster than shorter cracks. T F 9. It is not safe to use a material for structure applications with no fatigue limit. T F 10. Fatigue limit is the maximum value of the applied stress amplitude where materials can withstand infinite number of repeating cycle. T F 11. Fatigue life can be characterized by the number of repeating cycles for crack initiation. T F 12. All things been equal, the system with lowest value of the mean stress will have longest fatigue life. T F 13. Failure surface of high cycle fatigue failed specimen will contain both smooth and rough regions. T F 14. Creep is a thermally activated mechanical deformation under a constant load. T F 15. The activation energy for creep is usually not influenced by the applied load. T F 16. The creep rate will increase with time in the primary creep region. T F 17. The creep rate will increase with time in the secondary creep region. T F 18. Area under the stress‐displacement curve has a unit of Pascal. T F 19. Brittle‐to‐ductile transition temperature depends on the rate of deformation. T F 20. In the secondary creep region, the strain hardening is balanced by the recovery. T F