'DETERMINATION OF THE MAGNETIC VISCOSITY FOR COLD-ROLLED CARBON-STEEL 55-GALLON DRUMS IN THE EARTHS MAGNETIC FIELD'

摘要

Containers that are used to transport hazardous waste are usually drums constructed of cold-rolled carbon steel with a volume of 55 gallons. During the drum manufacturing process, the annealing,extruding, and cold rolling of the steel into sheets exerts stresses on the steel's microstructure whichdestroy pinning sites between magnetic domains, allowing these domains to rotate and elongate withless required energy, resulting in magnetically softer steel. When a magnetically soft sample isstationary and subjected to an external inducing magnetic field, the time it takes for the sample toacquire its magnetization is a function of the sample's magnetic viscosity. For drums that are moved inthe Earth's magnetic field, it is the drum orientation that changes within a stationary inducing magneticfield. If cold-rolled carbon steel has magnetic viscosity, the repositioned drum will require time tomagnetize in response to the new orientation, and the induced field from the steel will require time toreach its maximum value of magnetization. These experimental results show that cold-rolled carbonsteel in 55-gallon drum geometry does exhibit an induced magnetic field and the orientation of this fieldchanges when the drum is repositioned 180 degrees from a stationary position. The magnetic viscosityof the steel was calculated through linear regression of the magnetic field recovery curve from threeseparate drums using multiple fluxgate magnetometer sensors. The magnetic viscosity ranges between0.6 and 14 nT per minute in an Earth's magnetic field of approximately 55,000 nT.