Title: The Affects Of Heat On The Magnetic Properties of Iron and Plain Carbon Steels
Goal Of The Procedure:
As An Experiment: To have high school students determine the effect that elevated temperature has on the magnetic properties of iron and plain carbon steel .
As A Demonstration: Demonstrate the effects of heat on the magnetic properties of iron and carbon steel causing a loss of magnetic properties at a definable point, and upon cooling below that point the magnetic properties return.
This presentation will be confined to laying out the basic procedures and the instructor using this presentation can adjust its focus as deemed necessary.
Equipment Required:
| (1) Pair of safety glasses (1) A propane torch or other suitable heat source. (1) Horseshoe magnet approximately 1-3" high (to small a magnet may lose its magnetism when heated.) (2) Pieces of iron or plain carbon steel such as steel washers or medium sized paper clips. These (2) pieces should be identified and marked as piece number 1 and 2 . (1) Digital thermocouple such as a Fluke Model 51 or Model 52 Digital Thermometer. Other reliable ways to track the temperature of the heated metal can also be used. (1) Clamp, vise or stand to support the magnet and metal while it is being heated. (1) Pair of pliers or other similar device that can be used to handle hot metal.
Procedure: (1) Set up a support system that will secure the magnet above desk top level so that the propane torch can be used to heat piece number (1) attached to the magnet. (2) Place metal piece number (1) against one of the sides of the magnet at the open end of the magnet. Position piece number (1) so that one end is magnetically attached to the magnet and the rest of the piece extends out into the air and away from the magnet. This will allow you to heat metal piece number (1) while reducing heat buildup in the magnet itself. (3) Place metal piece number (2) adjacent to piece number (1) on the magnet but far enough away so that it remains relatively cool. Metal piece number (2) will be the control to demonstrate that while metal piece number (1) looses its magnetic attraction for the magnet because of the heat, the cooler piece number (2) remains attached to the magnet. This will also assure youthat the magnet has not lost its magnetism due to the heat. (4) Attach the digital thermometer/thermocouple to metal piece number (1) so that you can track its temperature. Attach it away from the magnet so that you get readings only from metal piece number (1) and not the magnet. (5) Slowly heat metal strip number (1) with the propane torch directing the heat onto metal piece number (1) and away from the magnet. (6) When metal piece number (1) reaches 1414 degrees F (for iron) it will fall away from the magnet while the cooler metal strip number (2) remains firmly attached to the magnet. When metal piece number (1) falls away from the magnet the temperature of the piece should be recorded. Immediately pick up piece number(1) and hold approximately 1/8th inch from the magnet, and in a manner that allows the piece to move freely. When the piece cools below 1414 degrees F metal piece number (1) will again reestablish its magnetic properties and be attracted to the magnet.
Discussion Points Following the Procedure/Experiment : (1) What happened when the heat was applied to metal piece number (1)? (2) What happened to metal piece number (2) the (control) during the procedure? Why did it behave differently than metal piece number (1)? (3) Explain/discuss the observations and recorded data relating to appropriate principles of magnetic theory. (4) Have students compare their temperature recordings at the time of the loss and return of the magnetic properties and compare them to reference data found in text or other appropriate reference materials. Discuss reasons for any variations or redo procedure to check verify results. Word 97 doc file of this project: drake.doc
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