Magnetoelastic behavior of DP steel in biaxial mechanical loading condition - Equivalent stress for magnetostriction

Online non-destructive magnetic monitoring is used to control the quality of steels subjected to multiaxial stresses. Due to magneto-elastic effects, a correction of non-destructive signal is necessary requiring the use of predictive magneto-elastic models on the one hand, and magnetoelastic measurements carried out under biaxial stress conditions on the other hand. Among magneto-elastic properties, magnetostriction under stress is particularly discriminent for models and the development of setups allowing for this measurement looks relevant. The first measurements of magnetostriction of a low carbon steel under biaxial stress have been reported in [1]. This set-up shows several drawbacks among which a low magnitude and inhomogeneous magnetic field. In this study, an improvement of the previous biaxial set-up is first proposed. Anhysteretic and cyclic magnetic and magnetostrictive measurements of a dual-phase (DP) steel are reported next. An analytical approach of the magneto-elastic modeling is proposed on the other hand, leading to the proposition of new equivalent stress formulations applicable for magnetostriction.