Abstract
The cold rolled Si-Fe sheets used for the production of the current cores for electricity meters suffer from ageing which causes an irreversible change in the magnetic properties. The ageing process is due to the precipitation of mixed iron silicon carbides in the microstructure. There exists already a thermal treatment and magnetic properties measurements method to detect the susceptibility to ageing. This requires a minimum of 1000 hours. In order to find the correlation between magnetic ageing, composition and metallographical evidence of ageing, different Si-Fe sheet compositions were investigated using the optical microscope to observe the time to appearance of visible carbide precipitates after ageing at 150°C and 200°C. It was found out that ageing does not occur below a certain carbon composition and that the time required for evidence of ageing to be visible increased with decreasing carbon content. It was concluded that the combined thermal treatment and metallographic examination does not bring the saving in time expected and that carbon analysis of the electrical sheet would be a better control.
Recommended Citation
.Tesha, J. (1988). Relationship between Magnetic Ageing, Metallographic Evidence of Ageing and Composition for Cold rolled Si-Fe electrical sheets. Tanzania Journal of Engineering and Technology (TJET), 12(2), 41-63. https://doi.org/https://doi.org/10.52339/tjet.v12i2.87
Publisher Name
University of Dar es Salaam