Approach to the anhysteretic Surface

In this paper, we have investigated experimentally the approach to the anhysteretic surface in M-H-σ space. In particular, for a 0.5 wt% carbon steel specimen, we have applied 73 MPa tension and a bias field H and determined the end flux density after superimposing an ac field of amplitude gradually decreasing to zero. We find that the point on the anhysteretic curve for 73 MPa tension and field H is not approached unless the initial amplitude of ac field is sufficiently large to overcome domain wall pinning, which restrains redistribution of the domains. A similar experiment in which stress is cycled was also done. Stress was cycled discretely between O and 140 MPa, with the discrete changes about 73 MPa eventually decreasing to zero in bias field H. It was found that the loci of (B,H) end points did not approach the anhysteretic, suggesting that larger amplitude changes in stress and perhaps more continuous changes are needed to overcome domain wall pinning. © 1996 American Institute of Physics.