Reference no: EM131069745
Objective: To study the time and temperature variations in the hardness of Al-4% Cu alloy on isothermal aging.
Introduction
Materials can be hardened by inhibiting the motion of crystal defects called dislocations. In pure metals, the presence of defects (such as vacancies, interstitials, dislocations and grain boundaries) can enhance the strength. In single phase alloys, additional resistance to deformation may arise from the presence of foreign atoms. In two-phase alloys, additional stress is needed to enable the dislocation to intersect the second-phase particles. A finely dispersed precipitate may, therefore, strengthen the material. This phenomenon is termed precipitation hardening.
Procedures
1. Stamp the five 2024 Al specimens with an identifying mark.
2. Measure the hardness of all of the specimens using Rockwell B.
3. Place all five in a heat-treatment crucible and into a furnace for solution treatment at 500°C (930°F) for 30 minutes.
4. Natural Aging - Remove one specimen and drop into a pail of water. Once the specimen is cool, measure the Rockwell B hardness at intervals of approximately 30 min, 90 min, 1 day, and 1 week for this specimen. It will be necessary for one member to come back to the lab during the week when the lab is in session to measure the hardness.
5. Artificial Aging - Remove the remaining four specimens and drop them into a pail of water. Once the specimens are cool remove them from the quenching bucket. Measure the Rockwell B hardness. Next, transfer the specimens to a furnace set at 190°C (370°F).
Remove one sample after 3 min, 10 min, 60 min and 90 min. Quench into water and measure the Rockwell B hardness. After one week, again measure the Rockwell B hardness of the 3- and 10-minute artificially aged specimens.
Write Up
1. Prepare a memo report.
2. Plot the hardness vs. time of aging for each aging temperature, using Excel.
3. How does aging temperature affect the time and hardness?
4. What happens to the 190°C (370°F) 3 and 10 minute specimens after one week? Why?
5. If you were going to use 2024 Al in an application at a temperature of 190°C (370°F), what problems could be encountered?
6. Discuss errors in this experiment and their sources.
Attachment:- assign.rar
|
Psychological contract expectations of your boss
: What are your psychological contract expectations of your boss and coworkers? Give examples of conflicts you have had at work, listing the expectation that was not met.
|
|
Find a hospital in your area
: Go to www.jointcommission.org. Click on Quality Check and find a hospital in your area. View the accreditation quality report. Describe what you have learned about this hospital. How could health care consumers use this site in deciding where to s..
|
|
Discuss the beneficial or detrimental effects
: Discuss the beneficial or detrimental effects of the overloads on the fatigue life
|
|
Next performance improvement project
: Describe where this hospital needs the most improvement and why. Describe what you think the most important opportunity for improvement is. Recommend where to focus the next performance improvement project.
|
|
How does aging temperature affect the time and hardness
: How does aging temperature affect the time and hardness? What happens to the 190°C (370°F) 3 and 10 minute specimens after one week? Why?
|
|
Distance of total crack growth under constant amplitude
: The fatigue crack is propagated ahead of a stress concentration under a constant amplitude of imposed cyclic compressive loads. The cracks arrest naturally after advancing a distance of ten times the notch-tip radius. At this point, the notched sp..
|
|
Discuss the different types of advance directives
: Discuss the different types of advance directives and the pros and cons of each. Do you have an advance directive? Has what you have learned this unit caused you to consider the need for one? Why or why not?
|
|
Delegation at boyne usa resorts
: Detroit native Everett Kircher moved to northern Michigan in 1947 and purchased land (for the price of $1) necessary to start his first ski resort known today as Boyne Mountain. Kircher practiced a traditional chain of command in a vertical organi..
|
|
Risk of using a signed public key
: Describe a scenario where the risk of having an unsigned public key is not acceptable but the risk of having a signed public key is acceptable. Describe a scenario where risk of using a signed public key is not acceptable
|