EFFECT OF HEAT-TREATMENT ON CRYSTALLOGRAPHIC AND MAGNETIC-PROPERTIES OF MAGNETIC STEELS

The keeper and the head of a modem electrovalve for electronic injection can be successfully realized using AISI 430 ferromagnetic steel. Important improvements in the performance of the device, mainly in terms of its regularity and energy savings, are possible by means of a better comprehension of the origins of the steel's magnetic properties. The magnetic behaviour of the AISI 430 steel upon different heat treatments was investigated, looking for the best compromise between time saving in the heat treatments and the ensuing magnetic properties of the material. In particular, the relationships between the structural effects of the heat treatments and the magnetic behaviour of the samples were studied. Values of the coercive force H(c), residual induction B(r), maximum permeability mu(max) and the approach to saturation values for H and B were determined by mean of a computerized permeameter, based on a Sanford-Bennet closed yoke for differently shaped samples.