3. (a) Explain why metals plastically deform at a stress many times lower than their theoretical strength. (3 marks) (b)

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3 A Explain Why Metals Plastically Deform At A Stress Many Times Lower Than Their Theoretical Strength 3 Marks B 1 (76.13 KiB) Viewed 11 times

3. (a) Explain why metals plastically deform at a stress many times lower than their theoretical strength. (3 marks) (b) Discuss how metal crystals can be strengthened by alloying elements in solid solution and why in certain alloys (e.g. carbon steel) this can lead to a ‘yield drop'. (5 marks) (C) Explain the stages of strain hardening, in terms of the characteristic stress-strain curve response seen for each stage and the dislocation interactions that give rise to (7 marks) this response. (d) If there is no recovery, show that the increase in flow stress due to stage II strain hardening can be described approximately by: At = a Gb y0.5 where; At is the increase in shear resistance due to strain hardening, G is the shear modulus, b is the Burger's vector, a is a constant, and y is the shear strain. (5 marks)