Biaxial stress effects on the magnetic properties of pure iron

Abstract

Samples and measurements Discs 40 mm in diameter were cut from sheets of 99.5% pure iron, I mm and 0.5 mm thick. The coercivity at zero stress was about 230 A/m and 280 A/m respectively for the two samples. The samples were mounted in the biaxial stress system described elsewhere. The initial and anhysteretic magnetization curves were measured at zero stress. Isostress hysteresis loops were measured for a range of values of the stress components ax and ay in the range i30 MPa for the 1 mm thick sample. From these were derived the coercivity Hc and the change in coercivity from the zero stress value, AHc = HC (ax , ay) - Hc (0, 0). Isofield measurements were made with the 0.5 mm thick sample of the irreversible magnetization change AMi,, induced by application and removal of stress in the range i50 MPa. The field (in the x-direction) was varied over a wide range to study the behaviour when H&&,