Cold Working a Copper Alloy
STANDARD VS EXPERIMENTAL PLOTS FOR COPPER ALLOY KYLE HOSSLI, MIKE RANIS, MOHAMMAD ALI SRJC, ENGR45, SPRING 2014 What is Cold Working?
Cold working, also known as Work hardening, is the process of strengthening a metal by plastic deformation. Plastic deformation occurs when a material is altered past its region of elasticity. This can be done by several methods such as: rolling, drawing, pressing, spinning and etc. On the microscopic level, the dislocations within the material are moving. Importance of Cold Working
Cold Working is important because it allows a user to alter the mechanical properties of the material into properties that the user needs. Cold Working does not just affect hardness of material but also: the yield strength, tensile strength, and ductility. This process is also very helpful because it does not require any heating, it decreases the cost of hardening. Our Semester Project?
For our semester project, we are taking 4 samples of Wrought Copper alloy (Cartridge Brass), 70 Cu- 30-Zn, and cold working them to 10%, 20%, 30%, and 40%. We will take all the point from each hardness and plot them on a hardness vs % Cold work graph. We will create to plots, one that calculates the %Cold work using area, and the other using thickness. Finally, we will compare each plot to a standard plot provided by L.H. Van Vlack, Elements of Materials Science and Engineering, 4th edition. The Experiment-Equipment
1. Calipers 2. Rollers 3. Rockwell Hardness Tester 4. Furnace
1.Calipers 2. Rollers 3. Rockwell Hardness Tester 4. Furnace The Experiment- Procedure
1. First, we took all 4 samples of 70 Cu- 30 Zn and put them in the furnace at 600 °C. The samples were annealed for one hour. 2. The samples were allowed to thoroughly furnace cool for 1 week.
3. Initial hardness measurements were taken for each of the 4 samples
4. We rolled each piece to slowly reach our desired % cold work
5. The desired % cold work was determined by measuring the thickness of each sample after each time through the roller.
6. Upon reaching the desired % cold work we measured the new hardness of each sample twice, and took the average as the final measurement. Our Samples: Cold work Progression Our Samples: Cold work Progression continued Data Analysis Data Analysis Continued The Experiment-Results Comparison
Standard Experimental Results
The experimental hardness curve is shifted up from the standard curves. This suggests our copper alloy had a higher Zn concentration because this follows the trend of the standard curves. Potential Sources of Error
Our main sources of error were due to issues with the equipment used during the experiment.
Rollers & the resulting shapes of the metal… (issues with our area analysis)
The Rockwell Hardness Testers have not been calibrated in years…
Industry standards recommend calibrations once every three months… “ensuring that the scope is reading accurately, the load being applied is consistent and the steel ball has not been worn or deformed.”
Importance of Results
The importance of our results is that many data points are required to form a very precise representation of the hardness vs % cold work graph. Also that the equipment used must be calibrated as well as maintained. Cold working is a very important form of hardening. It is a tool that has been used since the beginning of mankind. In this day in age, the amount of precision has become a very important factor in manufacturing processes. Cold working is a viable method as well as inexpensive method to aid in the manufacturing process. Work Cited
http://www.keytometals.com/page.aspx?ID=CheckArticle&site=kts &NM=266
http://metals.about.com/library/bldef-Cold-Working.htm
http://en.wikipedia.org/wiki/Work_hardening
Materials Science and Engineering: An Introduction, 8th Edition, William Calister
The Team
Mohammad Ali Mike Ranis Kyle Hossli