Cold Working and Thermal Treatment Procedure

ColdWorking and Thermal Treatment Procedure

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ColdWorking and Thermal Treatment Procedure

Thesample piece of copper was cut using a high speed abrasive saw(equipment details are in Table 1. Pictures are in the appendix) intotwo pieces measuring 0.25” and 0.75”. The 0.25” piece served asthe control while the 0.75” piece was the cold-work piece. TheRockwell HRF scale was used to measure three hardness readings of thecontrol piece. The measurements were recorded and the control pieceset aside.

Usingthe calipers, the initial thickness of the cold-work piece wasmeasured and recorded. A rolling mill was then used to decrease thethickness of the cold-work piece by 10%. Three hardness readings ofthe 10% cold-work piece were then taken and recorded. The procedureon the cold-work piece was repeated again at 20%, 30%, 40% and 50%making sure the piece was flattened using a mount press after eachbenchmark percentage was reached. Marking the piece ensured it wentthrough the roller in same direction each time.

Aftercold working the piece to 50%, the abrasive saw was used to cut itinto two pieces. While one half was set aside, the other underwentthermal treatment by placing it in a furnace at 5000Cfor 15 minutes until it was fully annealed. The cold worked piece,the thermal treatment piece and the control piece were then placedvertically in a disposable cup with the edge corresponding to therolling direction placed bottom down. They were then covered withepoxy mixed with powder at a ratio of 2:1.

Afterletting the epoxy cure for approximately 10 minutes, the disposablecup was removed and discarded. To ensure the disk would fit into thegrinding machine housing unit, a belt sander was used to trim itdown. Using the following sandpaper grits, sequential grinding wasthen done to prepare the samples. 240 grit for 8 minutes, 400 gritfor 4 minutes, 600 grit for 4 minutes, 800 grit for 3 minutes, and1200 grit for 4 minutes. Samples were then dropped onto kimwipes toprevent scratching after grinding was complete.

Togive the samples a mirror finish, alumina suspension and a microfibercloth on a polishing machine were used. Taking care not to touch thepolished surface, the samples were then rinsed off under runningwater then dried using kimwipes. An etchant solution containing 10 mlNH4OH,10 ml H2O,and 4 ml H2O2wasthen used to etch the surface of the samples until they revealed thegrain boundaries which could then be measured. An electron microscopeset at 400x magnification was used to look at the microstructure ofeach of the three samples. Separate pictures with the grainmeasurements of the samples were taken and saved for data reportinglater in the report.

Table1. Apparatus used during the experiment

Apparatus

Model Designation/Model Number

Figure Number

Saw

High Speed Abrasive Cut-off Saw/SYJ-30

6

Harness Tester

ME-2 Rockwell Hardness Testing System/MC2 RDS

7

Cold Roller

Durston Roller/F 100

8

Mount Press

Specimin Mount Press/531

9

Furnace

KSL-1200X-M

10

Epoxy

QuickSet Liquid and Powder

N/A

Sander

Wen Belt and Disk Sander

11

Grinding Machine

Buehler Ecomet 4 Body, Euromet 1 Head

12

Polishing Machine

Mark 5 Lab 2B

13

Microscope

BioImager ScopeImage-HD9, .5x C-Mount

14