|MadSci Network: Engineering|
Hi Bud, The physical properties of steel do not change after exposure to strong AC magnetic fields. The force exerted on the steel by the magnetic field is not normally strong enough to cause permanent changes in crystaline structure, which would produce changes in physical properties. Heating of the steel does occur, and induction heating is a commonly used method for melting steel. An AC field is used to demagnetize steel before attempting to measure the permeability. This is done to remove the magnetization caused by the Earth's magnetic field. The permeability measurement will not be accurate, if it is measured without first demagnetizing the steel. Bob Novak Specialist - Process R&D Carpenter Technology
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