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Unformatted text preview: When temperature increases, how do work hardening coefficient, strain rate sensitivity and strength coefficient change? Ans: When Temperature increase, work hardening coefficient n decrease, strain rate sensitivity m increase, and strength coefficient k decrease. 2) At strain (ε), the average flow stress is equal to 60% of the instantaneous flow stress. How much is the work hardening rate? At strain = 1.5 ε, what is the ratio of the average (Thread on bolt) (1) (2) flow stress to the instantaneous flow stress? (hint: it may change or may not change). Ans: Y f= Ke n n +1 = 0.6 Ke n n = 2 3 Y fY f = Ke n n +1 Ke n = 1 n +1 The ratio of the average flow stress to the instantaneous flow stress is independent to the strain. So at strain = 1.5 ε, the ratio does not change....
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 Spring '08
 Chunghorng,R
 Force, Strength of materials, Metalworking, Work hardening, Forging, instantaneous flow stress

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