Question

2. (3 x 6 = 18 Points) A strain-hardenable rod is stretched beyond its yield point, from original length , to l (>l.). Answer the following questions: (1) During this loading, in microscope a. Atomic distance doesn't change b. Atomic distance increases, but dislocations don't move c. Atomic distance increases, and dislocations move (2) If the rod is completely unloaded, in macroscope a. The rod length will return to its original value lo b. The rod length will remain as lf c. The rod length will be between l, and I (3) If the rod is completely unloaded, when you measure the properties of this deformed rod, you will find that its a. Yield strength increases and the ductility decreases b. Yield strength and ductility both increase c. Yield strength decreases, and ductility increases

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