INFLUENCE OF COLD DRAWING ON MAGNETIC-PRO PERTIES OF NONORIENTED 3-PERCENT SIFE ALLOYS

Magnetic characteristics were measured on stress-strain test pieces of non oriented 3 %SiFe with a magnetic measurement frame. Plotting vari ous magnetic properties against plastic deformation shows an exponenti al damage for low and medium values of magnetic field amplitude. This phenomenon is much weaker when high magnetic field amplitudes are reac hed. Metallurgical state of the material between 0 and 0.5 % is charac terized by the Luders strain state, which involves an important hetero geneous dislocations structure inside the metal die. After this, dislo cation structure remains more and less homogeneous from 0 to 10 % stra in (small tangles and isolated dislocations). These two dislocations s tructures are the more harmful for the magnetic properties of the allo ys. From epsilon(p) = 10 % to fracture, dislocations configuration bec omes progressively inhomogeneous and walls of high density are created but any supplementary magnetic damage is observed. Potential theories are not able to explain our experimental results but domain wall bowi ng theories could successfully be applied. Coercive field versus plast ic stress displays two distinct linear evolutions against three in the case of polycristalline high-purity iron, as shown by others authors.