Question

II- Given 2 brass specimens with initial dimensions as follows: Specimen #1: rectangular cross-section (12 x 20 mm) Specimen #2: circular cross-section (Ø = 15 mm) Both specimens were cold worked until the final cross-section area became 100 mm2. a) (6) Calculate the percentage of cold work for both specimens. b) (3) After cold work, both specimens were heated at different temperatures in order to reach full recrystallization in one hour. Which specimen will require lower heat treatment temperature? Explain c) (4) Draw the microstructure before and after cold work. d) (3) After cold work, what are the three stages of the annealing process with time (in sequence) e) (6) Draw a sketch of the microstructures during each of the annealing stages.

Answer 1

Dear student,

Here I given a brief explanation of cold working process and reason that specimens required dicgrent recrystallizaton temperature and impact of degree of cold work on recrystallizaton temp,

Soin 30-07-2020 Given 240mm Arect = 12420 mm2 Aer = 1 x 152 = 176.7145. Afinal = loomme original Us. Area final il's fren. Ao- Af %CW = Ao a ) Rect = (240- -100 X 100 240 0.582% loo Y. CAN = 58.3% Crumar loo 176.7145 %(w= Xlon 176.7145 Z.CN.= 43.4115 % 7.ch of Rectangle section & greater than 7. CAN of Cirullar Section percentage of cold Work is a measure of degree of Cold. lore. (plastir deformation). high > ps cold more * As the degree of lower Reery stractization is easy. (Octter at temperature

reguiment for recrystanization decreses. Because; the degree of cold wore increses the dislocation 2 quantity * This will increse the internal energy energy - Rectangular Apecimen regrine lower bear treatment temperature (C) Microstruche :- Equaxiled grain Elogated grapn in (Before Cold work) Strain direction (Aster Cold-work) (d). Annealing process: Recrystalleret Grain growth Temp Recovery Time

ce) After. Recovery. After. Cold Horked elongated grain Recrystalization After grain growth.

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