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Unformatted text preview: Title: Mechanical Working of Brass Objective : The OLD BBQ Co has sold fireplace rods made from brass that has been cold rolled 50% to give a nice spring-like feel. Complaints have come from customers that these are easily deformed after using. Determine the effect of mechanical and thermal treatments on the brass to try and duplicate the problem and identify what is occurring and present a possible solution. Procedure: Measure the Rockwell B or F hardness of the Brass at a smooth point on the surface and record. Take several readings and average. Cut a small sample (about to inch long) from the as-cast strip and retain for microscopy. Roll the brass, to 25 % reduction in thickness. Place the rolled brass in the furnace set at 700 C for 15 minutes. Remove and cool in water. Cut a small sample from this section and retain for the next lab and measure the hardness. Assume at this stage, the sample thickness at this point corresponds to 0% reduction. Continue the rolling stopping at approximately 10%, 25%, 50% and 75% reduction to measure the hardness and take samples. Place the rolled brass in the furnace set at 700 C for about 15 minutes. Allow to air cool until no longer red, then you may cool in water. Measure hardness and cut another small sample. Place the samples in the epoxy mounts so that each sample has the same orientation. Place one sample in one mount. Mix the epoxy and fill the mount with epoxy so that you sample is not moved. Wait 10 minutes and check to see if the epoxy is set. Label samples. Observations & Data: Condition of Brass: Thickness (mm): Measured Hardness (B or F scale): Average Hardness (B or F scale): Average Hardness (Vickers Scale): As Cast 3.86 58.3, 68.6, 55.7 (F) 60.9 (F) 73 0% (recrystallized) 2.95 64.3, 59.3 (F) 61.8 (F) 74 10% 2.64 80.0, 80.8 (F) 80.4 (F) 91 25%...
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- Spring '07