Numerical Simulation And Experimental Investigation Of Magnetic Hysteresis Loop And Barkhausen Noise Affacted By Multiple Factors In Ferromagnetic Materials

Ferromagnetic materials are the most important structural and functional material with wide applications.The properties of magnetic materials are usually determined by many factors,such as element composition,micro-structure,and stress state.In recent years,the research on non-destructive evaluation of component proportion,stress and mechanical properties by measuring the magnetic properties of materials has become a hot topic.For example,some feature parameters of hysteresis loop and magnetic Barkhausen noise(MBN)are sensitive to micro-structure and stress changes.The hysteresis loop and MBN are affected by many factors of material properties at the same time.And,it is difficult to separate the weight of each factor in the magnetic evaluation of material properties.Therefore,it is urgent to develop numerical models or experimental methods to study the change rule of material hysteresis loop and MBN under the action of multiple factors,so as to lay a foundation for the development of material performance magnetic evaluation technology.In this paper,the Ising model is extended,and the hysteresis loop and MBN under the action of multiple factors are obtained by numerical simulation.The validity of the numerical models are demonstrated by experiments,and the effect and weight of multiple factors on the magnetic feature parameters are analyzed and discussed.The main research contents include:(1)The construction method of Ising extended model for numerical simulation of hysteresis and MBN signal considering multiple factors.The range of spin state is extended in the original Ising model,and the spin value at the pinning position is defined as 0.The relationship between the number of pinning and the simulated carbon content is established,and the Ising model considering carbon content is proposed.For the two-layer ferromagnetic materials,the double Boltzmann function is introduced to replace the spin interaction coefficient in the original Ising model,and the Ising extended model suitable for the two-layer ferromagnetic materials is established.For the two-phase ferromagnetic materials,the Ising extended model is established by meshing the spin plane and assigning the spin interaction coefficients of two single magnetic phases.On the basis of the above model,the equivalent spin interaction coefficient is described as a polynomial of stress,and the Ising extended model considering stress action is established.(2)Experimental verification and test analysis of the predicted results for hysteresis and MBN signal simulation under the action of multiple factors.A series of special specimens were prepared.The two-layer ferromagnetic materials are constructed by laminated 45 steel sheet and 65 Mn steel plate.The ferrite and tempered martensite two-phase ferromagnetic materials with different componentproportion were obtained by adjust heat treatment temperature.In addition,carbon steel specimens with different carbon content were also prepared.A synchronous testing system for the total hysteresis and MBN of the specimen under uniaxial tension is constructed.The effects of carbon content,thickness,component proportion,stress and other factors on magnetic parameters are studied in details.The test results were used to verify the validity of each extended Ising model.(3)Numerical simulation and experimental test of hysteresis and MBN signal under the action of carbon content and stress.Considering the effect of carbon content and stress at the same time,the influence of carbon content and stress on hysteresis and MBN signal is analyzed by numerical simulation using the extended Ising model.The uniaxial tensile tests of carbon steel specimens with different carbon contents were carried out,and the hysteresis and MBN signals were measured synchronously.For MBN signal,numerical simulation and experimental results both show that the peak value of MBN envelope increases linearly with the increase of stress.For the hysteresis loop signal,the numerical simulation results show that the coercivity decreases linearly with the increase of the simulated stress.However,the experimental results are affected by multiple factors,the coercivity of specimens with different carbon contents varies with the stress.(4)Numerical simulation and experimental test of hysteresis and MBN signal for two-phase materials under stress.The Ising extended model of two-phase materials and the Ising extended model considering stress are superposed to realize the numerical simulation of hysteresis and MBN signal under the combined action of component proportion and stress.For experimental verification,the uniaxial tensile test was carried out on the specimens of dual-phase steel with different component proportion,and the hysteresis and MBN signal were synchronous tested.The wight of stress and ferrite proportion on the magnetic feature parameters was studied.The results show that the ferrite proportion is the dominant influence factor when ferrite proportion is less than 12%,and the weight of stress and ferrite proportion are in the same order when ferrite proportion exceeds 12%.The weight of ferrite proportion on the feature parameters of hysteresis loop(coercivity and saturation magnetic induction strength)is higher than stress.