4. Your first job out of school is at a paper clip factory; you are in charge of the wire drawing facility. The wire drawing dies only operate in cold working mode. Stock material: 1040 Steel: 1.48 mm diameter; 0% CW a) Your boss offers you a bonus if you can process the stock 1040 steel wire to make paper clips with a final wire diameter of 1.00 mm with the tensile strength above 860 MPa with ductility above 12% EL at the minimum number of process steps. Assume that 1040 steel experiences cracking at 38% CW. Explain to your boss your cold working/annealing method so that you can get your bonus! [5] b) Schematically draw stress (o)-strain (e) curves of the steel wire to compare the mechanical properties before and after processing. Be sure to indicate which one is which. [3] c) A new magnesium alloy material, AZ31, is introduced to your facility. For AZ31, 00 = 3 MPa and ky = 0.5 MPa-m/2. What is the mean grain size to achieve the tensile strength of 860 MPa? Assume that the tensile strength of AZ31 is 2.75 times its yield strength. [3] d) In the rectangle at left and right, draw the final microstructure of steel wire from parts a) and b), respectively. Label your micrographs (Hint: Draw (i) shapes of grains and (ii) characteristics that can be found inside the grains) [4] 5/23 Drawing Direction /15