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:

MSE 201 LAB II: Part bMSE 201 LAB II: Part b

Annealing Copper AlloysAnnealing Copper Alloys

Lab OverviewLab Overview

• Each alloy (Pure, 5% Zn, 10% Zn, 20% Zn) will Each alloy (Pure, 5% Zn, 10% Zn, 20% Zn) will be annealed for 45 minutes at 8 be annealed for 45 minutes at 8 temperatures:temperatures:

200°C, 250°C, 300°C, 350°C, 400°C, 500°C, 200°C, 250°C, 300°C, 350°C, 400°C, 500°C, 600°C, and 800°C600°C, and 800°C

• Hardness after each anneal will show amount Hardness after each anneal will show amount of recrystallization or grain growthof recrystallization or grain growth

• PROCEED TO FURNACE ROOM TO CONDUCT PROCEED TO FURNACE ROOM TO CONDUCT ANNEALINGANNEALING

What is Recrystallization?What is Recrystallization?• Recovering damage and forming new grains by Recovering damage and forming new grains by

addition of heataddition of heat

(click to play)

Stages During AnnealingStages During Annealing• I: RecoveryI: Recovery• II: RecrystallizationII: Recrystallization• III: Grain GrowthIII: Grain Growth

Hardness vs. Annealing Temp

25

75

125

175

0 200 400 600 800

Temp, °C

Har

dn

ess,

DP

H 20% Zn

10% Zn

5% Zn

Pure Cu

Goal: Goal: Plot of Hardness vs. Annealing Plot of Hardness vs. Annealing TempTemp

I: Recovery

II: Recrystallization

III: Grain Growth

Joined PlotsJoined PlotsHardness vs. %CW and Annealing TemperatureHardness vs. %CW and Annealing Temperature

25

45

65

85

105

125

145

165

185

0 200 400 600 800

Annealing Temp, C

25

45

65

85

105

125

145

165

185

0 10 20 30 40 50 60

%CW

Hardn

ess,

DPH

http://www.copper.org/resources/properties/microstructure/brasses.html

Stress Free Grain

Grain Boundaries

Etch Pits

Annealing Twins

http://www.copper.org/resources/properties/microstructure/brasses.html

Slip LinesSlip Lines

Deformation BandsDeformation Bands

Distorted GrainsDistorted Grains

New Crystal Formation

Microstructure ExaminationMicrostructure Examination• 5% Zinc samples will be examined5% Zinc samples will be examined• Sample 242: Shows effects of % cold workingSample 242: Shows effects of % cold working• Sample 243: Shows effects of annealing temperature.Sample 243: Shows effects of annealing temperature.

• Look for:Look for:– Grain BoundariesGrain Boundaries– Stress Free GrainsStress Free Grains– Distorted GrainsDistorted Grains– New CrystalsNew Crystals– Deformation Deformation

BandsBands– Slip LinesSlip Lines– Annealing TwinsAnnealing Twins– Etch PitsEtch Pits– ScratchesScratches

After Removing Samples…After Removing Samples…

• Remove oxide scale with sand paperRemove oxide scale with sand paper• Average hardness results for each Average hardness results for each

sample (HRF/HRB) and convert to sample (HRF/HRB) and convert to DPHDPH

• Make sure data sheet is completely Make sure data sheet is completely filled outfilled out

• Place samples in recycle box.Place samples in recycle box.• Turn Data Sheet in to TATurn Data Sheet in to TA

Remember: There is a report DUE NEXT WEEK!Remember: There is a report DUE NEXT WEEK!