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quiz5spr2000

# quiz5spr2000 - ~ 11 1 ENGSC 3313 Spring 2000 Answer 1 any 4...

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~, 11- , 1 ...,- ,. ENGSC 3313, Spring 2000 Quiz 5 Name Answer any 4 Questions only, 1 point each Provided is an annealed red brass (85 Cu- 15 Zn) wire of diameter 1.5 rnm. Required is a 1.0 rnm diameter wire with the following properties. Tensile Strength > 500 MPa, Hardness (RB) < 85, % Elongation (50 rnm) > 5. Specify a processing sequence. 1 600 ~ c ~ ~ § -500 - -= 0 - ~ -= = .. " = h " :400 ~ 'i = ~ " 0 = ." '"" ... 0 10 20 30 40 SO 60 Cold work, % For strength, need > 50 % CW For hardness, need < 60% CW For ductility, need < 55% CW --CW = Cold Work Choose 52% CW ]so t3 ~60 ~ .E 40 ~ I §-20 15ZD ~ 1 , 0 r.: 0 10 20 30 40 50 60 Cold work, % The 50% recrystallization time (tSO) of pure Cu, cold rolled 98%, is 9 min. at 135°C and 250 min. at 88°C. What is tSO, in min., at room temperature, 25°C? lnt=B+C/T In (9) -In (250) = C 3h) => c = 10,417 mill ( 1 ' , " 1 \.408 In (150) -In (250) = (10,417) I 150 = 1.1 x 105 min I \298 A specimen of bronze of grain size 50 J.!In doubled its grain size when held at 650°C for 4.5h. The same grain size change occurred in 0.5h when a like sample was held at 700°C. What would be the hold time to double the grain size at 750°C. 3 Ref. Example 7-1.3, p. 223, text. Presume the rate increase to be exponential with temperature.

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quiz5spr2000 - ~ 11 1 ENGSC 3313 Spring 2000 Answer 1 any 4...

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