Influence of Stresses on Magnetic B-H Characteristics of X30Cr13 Corrosion Resisting Martensitic Steel

Abstract

Abstract. Paper presents the frame-shaped cores based methodology of testing of magnetoelastic characteristics of energetic steels such as X30Cr13 steel, subjected to tensile stresses. In presented method, the magnetic circuit of the sample is closed. For this reason, the results of magnetoelastic investigation are independent of the shape of the sample. To validate the proposed method, the influence of tensile stresses on B(H) hysteresis loop of X30Cr13 martensitic corrosion resistant steel was carried out. On the base of these result, clear criteria for non-destructive assessment of mechanical stresses in the material were determined.Keywords: magnetoelastic effect, corrosion resistant steel, stress assessment. IntroductionUnder the influence of mechanical stresses, the shape of B(H) magnetic hysteresis loop changes significantly for both crystalline [1] and amorphous [2] magnetic materials. This effect is commonly known as magnetoelastic effect [3,16]. In spite of the fact that changes of flux density B under stresses are most significant for high permeability amorphous and nanocrystalline alloys [4,5,6], the magnetoelastic effect is also observed in steels [7,8,9]. As a result, measurements of stress-induced changes of shape of hysteresis loop of steel, creates the possibility of non-destructive assessment of mechanical stresses generated during the use mechanical component. Magnetoelastic-effect based non-destructive testing of corrosion resisting steels can be considered only for the martensitic steels, such as X30Cr13 steel. Austenitic steels are non-magnetic, however, under specified mechanical stresses austenite may be conversed to martensite [10,11,12]. This phenomenon is also very interesting from the non-destructive testing point of view, but its principle is different than magnetoelastic effect in martensitic steels.Martensitic corrosion resisting X30Cr13 steel exhibits good resistance to the corrosive effect of salt water, weather and various corrosion agents. Moreover, this steel

Stress-Induced Anisotropy and Stress Dependence of Saturation Magnetostriction in the Jiles-Atherton-Sablik Model of the Magnetoelastic Villari Effect

“…To increase the speed of calculations, this step was carried out with reduced numerical accuracy. in this case, fixed-step fourth-order Runge-kutta method (50 steps) was used for solving differential equation (10), as well as 90 fixed-step trapezoid method was used for integration of equation (4).…”

“…In a general case, for anisotropic materials, this curve given by the equation [24,25]: (4) where θ is the integration parameter and E(i), is given by the following relationship [24]: (5) where a quantifies domain wall density, K an is the anisotropic energy density, ϕ1=ψ -θ and ϕ2=ψ +θ, where ψ is an angle between the easy axis of the material and the magnetizing field direction.…”

“…It should be indicated, that in the case of anhysteretic magnetization of the isotropic magnetic materials M an , where K an =0, equation (4) reduces to the Langevin equation [15]: (6) For isotropic materials integral in equation (4) has the antiderivative. As a result it can be reduced to the Langevin function in equation (6).…”

“…This effect is connected with the changes of flux density B (achieved for a given value of the magnetizing field H) in the material subjected to mechanical stresses σ. The magnetoelastic Villari effect was observed in steel [2,3,4], soft ferrites [5] as well as amorphous [6,7] and nanocrystalline [8,9] soft magnetic materials.…”

Assessment of the Magnetostrictive Properties of the Selected Construction Steel

“…In the center of the test stand in adapted holders (holders are integral parts of the reversor, Fig. 2), a frameshaped sample made of 13CrMo4-5 steel is placed (samples are known from papers [8][9][10]). Sample is placed into stresses reversor, which is put into hydraulic press.…”