Stress dependence of ferromagnetic hysteresis loops for two grades of steel

Residual stress is an essential input into calculations of the remaining li fe of operational plant. However, many Life predictions are inherently cons ervative because measurements of the absolute stress are unavailable. The m agnetic properties of material are sensitive to stress, and in this paper, the magnetic properties (at maximum magnetisation, at remnance, and at the coercive field) of two grades of steel (Durehete 1055 and AS1548-7-46OR) un der uni-axial stress are presented. The magnetic parameters are more sensit ive to compressive stress than to tensile stress. A mathematical model usin g the Jiles-Atherton theory for ferromagnetic hysteresis is used to explain the trends in the experimental data. The ability of magnetic techniques to measure stress is demonstrated. (C) 2000 Elsevier Science Ltd. All rights reserved.