Question

UTS Yield and Ultimate Strength (ksi) Elongation (%) Elongation 0% 20% 60% 80% 40% % CW a. The range in %CW where a bar of this material will have a % elongation of at least 15 and tensile strength greater than 120 ksi. Show your construction on the figure. b. What is the final diameter of a bar that starts at 1.2 inch diameter that will meet the property specification given above? C. This material is rolled from 1" to 0.8" thick, annealed, rolled to 0.6" and then rolled to 0.4" thick. What is the %CW in the material? Explain your reasoning. d. You must draw a wire from a diameter of 5 mm to 0.25 mm with a specification of minimum strength and ductility. The maximum %CW during drawing of this material is 50%. Explain the options among cold-work, annealing, and hot-work to meet the strength and diameter specifications.

Answer 1

Part A:

Step 1- Identify region with elongation > 15% -- this is region with %CW within 0 - 35%

Step 2- Identify region with UTS > 120 -- this is region with %CW greater than 20%

Thus, the final region is between 20-35%

UTS YS Yield and Ultimate Strength (ksi) Elongation (%) Elongation 0% 20% 40% % CW 60% 80%

Part B

Initial Bar Diameter : 1.2 inch

%CW = Final Area/Initial Area = (D_f²)/(D_i²)

=> D_f =

D; # sqrt(CW)

for CW = 0.2, Df = 1.2*sqrt(0.2) = 0.4472 inch

For CW = 0.35, Df = 1.2*sqrt(0.35) = 0.5916 inch

Part C:

Since material is annealed after rolling to 0.8inch - we have recrytallization - thus grain boundaries are redefined.

%CW = (0.4/0.8)²x100 = 25%

Part D

1. Hot rolling and annealing till 0.5mm - Thus the grain boundaries are not turning brittle. Then for the last step down, from 0.5mm to 0.25mm - cold rolling - thus %CW of 25%, and we can gain UTS and Elongation as per spec