IE370Quiz 3 solution - When temperature increases, how do...

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Quiz 3 Name and ID Multiple Choice 1. Friction in metal forming will result in: (a) retardation of metal flow during deformation (b) non-uniform deformation, and non-homogenous microstructure. (c) more forces and power requirement (d) less wearing of the tools. (e) better surface finishness. Ans: a,b,c 2. The best metal choice working processes for the following shape changes are (select one): (a) upsetting for (1) and machining (2) (b) rolling for (1) and thread rolling for (2) (c) extrusion for (1) and machining for (2) (d) heading for (1) and thread rolling for (2) (e) rolling for (1) and upsetting for (2) Ans: d True or False 1. Hot working has better surface finishness than cold working. False 2. Friction is one of the reasons to cause barreling effect in open-die forging. True 3. Cluster mill can reduce deflection and improve the geometric accuracy. True Calculation 1) Flow stress is function of strain and strain rate.
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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 (), the average flow stress is equal to 60% of the instantaneous flow stress. How much is the work hardening rate? At strain = 1.5 , 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 f-Y 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 , the ratio does not change....
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This note was uploaded on 09/23/2009 for the course IE 370 taught by Professor Chunghorng,r during the Spring '08 term at Purdue University-West Lafayette.

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IE370Quiz 3 solution - When temperature increases, how do...

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