Tip for Problem 1

A copper (pure copper) bar and eutectoid steel (assume the steel is bainite), bar “sitting on a table in the lab” are cut into several pieces. Your supervisor is confused about the behavior of pure copper (which melts at 1060C) and eutectoid steel (the eutectoid temperature is 727C) because of the following observations.

	Copper	Steel
700C	If I place a piece of the copper in a 700C saturated furnace for two hours and then slam it into a water bath; that piece of copper is weaker and softer, than the piece left “on the table” If I melt a piece of the copper and let it solidify at 700C and then slam it into a water bath it is harder and stronger than if I melt a piece of the copper, and let it solidify at 1050C, wait for it to solidify and slam it into a water bath. The piece of copper which was melted and then solidified at 700C may be stronger and harder than the piece of copper which was simply placed in a 700C saturated furnace for two hours and then slammed it into a water bath	If I place a piece of the steel in a 700C saturated furnace for two hours and then slam it into a water bath; that piece of steel is weaker and softer, than the piece left “on the table”
1050C	If I place a piece of the copper in a 1050C, furnace for two hours and then slam it into a water bath; that piece of copper is weaker and softer, than the piece of copper subjected to a similar heat treatment but at 700C. If I melt a piece of the copper and let it solidify at 1050C and then slam it into a water bath it is softer and weaker than if I melt a piece of the copper, and let it solidify at 700C, wait for it to solidify and slam it into a water bath. The piece of copper that was melted and then solidified at 1050C may be softer and weaker than the piece of copper that was simply placed in a 700C saturated furnace for two hours and then slammed it into a water bath	If I place a piece of the steel in a 1050C, saturated furnace for two hours and then slam it into a water bath; that piece of steel is harder and stronger, than the piece left “on the table” If I place a piece of the steel in a 1050C, saturated furnace for two hours and then turn the furnace off and remove the steel when the furnace is at room temperature; is weaker and softer, than the piece left “on the table”

Prepare a report explaining these observations. Use processing-structure-processing relationships as the basis for your report. Make sure your report explains the difference between the “behavior” of pure copper and eutectoid steel mentioned above.

This is a thought question . Consider the following:

• How will processing effect properties such as strength?
• How will structure effect properties such as strength?
• How will processing effect structure?
• In each case determine if a phase transformation will occur, and if so what transformation(s)
• What is the difference between heating from room temperature to a given temperature, and cooling molten metal to that temperature and letting it solidify?
• What is the difference between heating from room temperature to a given temperature, and cooling austenite to that temperature and letting it transform?
• How does average solidification temperature affect structure? Why?
• How does solidification temperature effect grain size?
• What is the role of annealing, coarsening, or grain growth, if any?
• In commercial terms alloys can be single element. They will usually have some impurities.
• Steel does not melt in any of the above experiments.
• A report needs to be well written, simply analyzing each observation independently will not be sufficient, and will result in little or no credit.
• You do not need a TTT diagram for copper to answer this question.
• As a first step in rough work analyze the observations in the table. You may want to use word processing software to place statements side-by-side and compare them. Remember a comparison includes similarities and differences.
• One or two long rambling paragraphs will result in little or no credit. This is a thought question.