APPLICATION OF THE VILLARI EFFECT IN A FATIGUE EXAMINATION OF NICKEL

This paper presents the possibility of using the reverse magnetostriction (Villari) effect in fatigue testing of ferromagnetic materials. The tests were conducted on cyclically loaded nickel with no auxiliary external magnetic field. The following properties were determined: magnetic induction B, magnetic field strength H, energy of the magnetic hysteresis loop ΔM (in the B–H coordinate system), plus such mechanical quantities as stress σ, strain ?, plastic strain ?_p and energy of the mechanical hysteresis loop ΔW (in the σ–? coordinate system). A variety of magneto-mechanical characteristics are presented and their susceptibility to loading parameters of the fatigue process are discussed. A relationship between ΔW and ΔM is demonstrated. The Villari effect is shown to be especially useful in determining the cyclic yield limit.