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Explore the impact of annealing at various temperatures on copper alloys with different zinc compositions. Learn about recrystallization, recovery, and grain growth stages, and examine microstructural changes. Conduct hardness tests for detailed analysis.
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MSE 201 LAB II: Part b Annealing Copper Alloys
Lab Overview • Each alloy (Pure, 5% Zn, 10% Zn, 20% Zn) will be annealed for 45 minutes at 8 temperatures: 200°C, 250°C, 300°C, 350°C, 400°C, 500°C, 600°C, and 800°C • Hardness after each anneal will show amount of recrystallization or grain growth • PROCEED TO FURNACE ROOM TO CONDUCT ANNEALING
What is Recrystallization? • Recovering damage and forming new grains by addition of heat (click to play)
Stages During Annealing • I: Recovery • II: Recrystallization • III: Grain Growth
Goal: Plot of Hardness vs. Annealing Temp I: Recovery II: Recrystallization III: Grain Growth
Joined Plots Hardness vs. %CW and Annealing Temperature
Etch Pits Annealing Twins Grain Boundaries Stress Free Grain http://www.copper.org/resources/properties/microstructure/brasses.html
http://www.copper.org/resources/properties/microstructure/brasses.htmlhttp://www.copper.org/resources/properties/microstructure/brasses.html
Slip Lines Deformation Bands Distorted Grains
Microstructure Examination • 5% Zinc samples will be examined • Sample 242: Shows effects of % cold working • Sample 243: Shows effects of annealing temperature. • Look for: • Grain Boundaries • Stress Free Grains • Distorted Grains • New Crystals • Deformation Bands • Slip Lines • Annealing Twins • Etch Pits • Scratches
After Removing Samples… • Remove oxide scale with sand paper • Average hardness results for each sample (HRF/HRB) and convert to DPH • Make sure data sheet is completely filled out • Place samples in recycle box. • Turn Data Sheet in to TA Remember: There is a report DUE NEXT WEEK!