Question 1: (Annealing) Fill in the table below as it relates to annealing:
|
Stage
|
Recovery
|
|
|
|
Change in microstructure
|
|
New grains nucleate
|
Grains Grow
|
|
Change in properties
|
|
|
Further reduction in strength, further increase in ductility
|
|
Temperature
|
Below Trc
|
|
Ø Trc
|
Question 2: (Cold working) Some of the properties of AA 2024 (Matweb) are show below:
|
Properties
|
|
|
UTS
|
27000 psi
|
|
Yield strength
|
11000 psi
|
|
Modulus of Elasticity
|
10600 ksi
|
1. Draw a stress-strain diagram for AA 2024 (conceptual). Annotate the properties along with values shown in the table above in the stress-strain diagram.
2. On the same stress-strain curve, using a dashed line, please construct the stress strain curve for the AA 2024 material that had been subjected to the 50% cold work. Explain the following:
a. Why did you estimate the modulus to be as you drew it?
b. Would you estimate the hardness to be higher or lower for the cold worked material and why?
c. Would you expect the % elongation to be higher or lower for the cold worked material and why?
Question 3: (Chapter refresher) Briefly explain in a minimum of one sentence about what you understood from each of the topics shown below.
Question 4: (Finding crystalline structure) Use the attached data file from the tensile test of a certain material to find its crystalline structure. This to attach with this homework for this problem:
1. Screenshot of your excel sheet showing the columns you calculated
2. Graph from which you calculated the strain hardening exponent
3. Value of strain hardening exponent and the corresponding crystalline structure.
| Metal |
Crystal Structure |
n |
K (psi) |
| Titanium |
HCP |
0.05 |
175,000 |
| Annealed alloy steel |
BCC |
0.15 |
93,000 |
| Quenched and tempered medium-carbon steel |
BCC |
0.1 |
228,000 |
| Molybdenum |
BCC |
0.13 |
105,000 |
| Copper |
FCC |
0.54 |
46,000 |
| Cu-30% Zn |
FCC |
0.5 |
130,000 |
| Austentic stainless steel |
FCC |
0.52 |
220,000 |