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MSE 201 LAB II: Part a

MSE 201 LAB II: Part a. Cold Rolling Copper Alloys. What is Cold Rolling?. Deformation below the “recrystallization temperature”. COLD ROLLING. HOT ROLLING. Lab Overview. 4 Alloys Rolled Today: Pure Copper 5% Zinc 10% Zinc 20% Zinc This is called “Alpha Brass”

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MSE 201 LAB II: Part a

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  1. MSE 201 LAB II: Part a Cold Rolling Copper Alloys

  2. What is Cold Rolling? • Deformation below the “recrystallization temperature” COLD ROLLING HOT ROLLING

  3. Lab Overview • 4 Alloys Rolled Today: • Pure Copper • 5% Zinc • 10% Zinc • 20% Zinc • This is called “Alpha Brass” • Solid solution of one phase (the alpha phase)

  4. Why Add Zinc? • Zinc hardens copper by “Solid Solution Hardening”. Cu: Z=29 Zn: Z=30 (click to play)

  5. Rolling Causes Deformation • Deformed microstructure has many more defects, thus it is harder. (click to play)

  6. Goal: Hardness vs. % CW Increased Dislocation Density with %CW Solid Solution Hardening

  7. How to Measure %CW? • Percent Cold Work (%CW) is the% Change in Cross-sectional Area. • Area of these samples = Width * Thickness.

  8. Making It Easier • Assume width doesn’t change.

  9. Using a Micrometer

  10. Using a Micrometer (cont.)Measuring to 0.001”

  11. Using a Micrometer (cont.)The Vernier Scale (0.0001”)

  12. Lab Procedure • Measure initial thickness • Calculate target thickness values for each %CW • Measure initial width, hardness • Roll sample to reach the target thickness (Set micrometer to target thickness for “pass-thru test” to save time) • Measure “Actual Thickness” • Measure hardness • Reset micrometer and go to step 4

  13. Notes on Hardness Measurement • Start with HRF scale (60kgf load) • If reading is >100 HRF, switch to HRB (100kgf) • If indent is visible on the back side of the sample, use superficial scale • HR30T for softer samples, or • HR45T for harder samples • Use “spot anvil” to negate curvature

  14. Upon Completion of Rolling… • Average hardness (HRF/HRB) and convert to DPH • Make sure data sheet is completely filled out • Write on your copper strip: • Alloy (Pure, 5%, 10%, 20%) • Class Time (1:25 or 3:25) • Team members’ names • Turn in to TA the following: • Data sheet • Copper strip • Micrometer NO REPORT DUE THIS TIME, BUT LAB MEETS NEXT WEEK TO FINISH THE EXPERIMENT!!! NO REPORT DUE THIS TIME, BUT LAB MEETS NEXT WEEK TO FINISH THE EXPERIMENT!!!

  15. Let’s Roll!

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