Some mechanical and magnetic properties of cold rolled X5CrNi 18-8 stainless steel

Purpose: The paper analyzes the influence of the degree of cold deformation on the structure forming and changes of mechanical and magnetic properties of cold-rolled sheet on austenitic X5CrNi18-8 stainless steel. Design/methodology/approach: The investigations included observations of the structure on a light microscope, researches of mechanical properties in a static tensile test, microhardness measurements made by Vickers’s method and magnetic behaviors determine by used normalized non-destructive testing methods (NDT). The analysis of the phase composition was carried out on the basis of X-ray researches. In the qualitative X-ray analysis the comparative method was applied. Whereas X-ray quantitative phase analysis was carried out by the Averbach Cohen method. Research limitations/implications: The X-ray phase analysis in particular permitted to disclose and identify the main phases on the structure of the investigated steel after its deformation within the range 10%-70%. Moreover results of the X-ray quantitative analysis allowed to determine the proportional part of martensite phases α` in the structure of investigated steel in the examined range of cold plastic deformation. Practical implications: The analysis of the obtained results permits to state that the degree of deformation has a significant influence on the structure, mechanical and magnetic properties of the investigated steel. Besides, it was found that the plastic deformation in cold rolling process of metastable austenitic steel type X5CrNi18-8 induces in its structure a phase transformation paramagnetic austenite into ferromagnetic martensite. Originality/value: plastic deformation in cold rolling process in the austenitic X5CrNi18-8 stainless steel a good correlation was found between changes of the structure and the effects of investigations of the mechanical properties, connected with martensitic α’ phases forming. Existing this relation is of essential practical importance for the technology of sheet-metal rolling of austenitic steel

Investigation of material properties by means of magnetic methods

In the present paper, magnetic method of determination of ferrite content in austenite steels, based on saturation polarisation and magnetic polarisation of ferrite near the remanence point, have been presented for Fe-Cr-Ni-type alloys. Magnetic phase analysis, taking into occount the distribution of total magnetic losses on eddy current losses, relaxation losses and hysteresis losses, have been discussed for low-carbon and low-alloy steels. The formulas on tangent angle of eddy current, hysteresis and relaxation (additional) losses have been presented. General formulas for magnetic permeability and coercive force have also been presented in terms of internal magnetic and material parameters. These parameters allowed to analyse the structural changes in magnetic materials. Examples of the influence of chemical composition, structural defects and thermal annealing on the changes of saturation polarisation, magnetic permeability, coercive force, magnetic hysteresis and relaxation losses have been discussed for low-carbon steels and amorphous alloys

The effect of (y->a') phase transformation on microstructure and properties of austenitic Cr-Ni steels

The paper presents the results of the investigations concerning the effect of (γ→α’) phase transformation on microstructure, magnetic and mechanical properties of austenitic stainless steel grade X5CrNi18-10. Design/methodology/approach: Light microscope examinations, microhardness measurements and static tensile tests were performed in order to reveal microstructure and changes in mechanical properties. The magnetic properties: relative magnetic permeability μ (Maxwell-Wien bridge) and coercive force Hc (permalloy probe) were measured at room temperature. The analysis of the phase composition was carried out on the basis of X-ray investigations. In the qualitative X-ray analysis the comparative method was applied. Findings: : It was found that the plastic deformation in cold rolling within the range 10-70% of investigated austenitic Cr-Ni steel induced in its structure a phase transformation of paramagnetic austenite into ferromagnetic martensite. Research limitations/implications: The results of the X-ray quantitative analysis allowed to determine the proportional part of martensite phases α` in the structure of investigated steel in the examined range of cold plastic deformation. Practical implications: A wide range of practical applications of austenitic X5CrNi18-10 steel sheets is warranted by both their high corrosion resistance and high plastic properties, especially in the supersaturated state. Besides, a strong correlation was found between the magnetic properties and the (γ→ α’) phase transformation. Originality/value: In the course of deformation, the volume fraction of martensite increased at the expense of the amount of austenite resulting in the hardening of the material. In general, a gradual increase of the yield strength results from the strain hardening of the austenite structure and formation of strain-induced martensite

Electrophysical properties of the multicomponent PbFe1/2Nb1/2O3 ceramics doped by Li

The paper presents the results of research on the influence of sintering temperature on microstructure, DC electrical conductivity, dielectric, ferroelectric and magnetic properties of PbFe1/2Nb1/2O3 ceramics doped by Li in the amount of 5.0% wt., in the abbreviation PLiFN. The ceramic samples of the PLiFN material were obtained by the two-stage synthesis – columbite method and sintered by free sintering methods. Introduction to the basic PbFe1/2Nb1/2O3 composition of the lithium admixture to decrease the electrical conductivity and reduction of dielectric loss. The tests have shown that the increase in sintering temperature orders the PLiFN ceramic microstructure, which has a positive effect on its electrophysical properties. At room temperature, the PLiFN ceramic samples show both ferroelectric and ferromagnetic properties. Considering the functional parameters of the obtained ceramic samples, the optimal technological conditions are 1100°C/2 h.[1] H. Schmid, Ferroelectrics 162, 317 (1994). [2] W. Cheong, M. Mostovoy, Nat. Mater. 6, 13 (2007). [3] K.F. Wang, J.-M. Liu, Z.F. Ren, Adv. Phys. 58, 4, 321-448 (2009). [4] D. Bochenek, J. Alloy. Compd. 504, 508-513 (2010). [5] D. Bochenek, J. Dudek, Eur. Phys. J.– Spec. Top. 154, 19-22 (2008). [6] G.A. Smolenskii, A.I. Agranovskaia, S.N. Popov, V.A. Isupov, Sov. Phys.-Tech. Phys. 3 1981 (1958). [7] G.A. Smoleński, W.M. Judin., Fiz. Twierdogo Tela 6, 3668 (1964). [8] Y.E. Roginskaya, Y.N. Venevcev, S.A. Fedulov, Sov. Phys. Crystallogr. 8, 490 (1964). [9] S. Picozzi et al., J. Phys. – Condens. Matt. 20, 43, 434208 (2008). [10] H. Schmid, J. Phys. – Condens. Matt20, 43, 434201 (2008). [11] W. Eerenstein, N. D. Mathur, J. F. Scott, Nature 442, 759 (2006). [12] K. Wójcik, K. Zieleniec, M. Mulata, Ferroelectrics 289, 107 (2003). [13] D. Bochenek, P. Kruk, R. Skulski, P. Wawrzała, J. Electroceram. 26, 8-13 (2011). [14] D. Bochenek, Z. Surowiak, J. Krok-Kowalski, J. Poltierova-Vejpravova, J. Electroceram. 25, 122-129 (2010). [15] D. Bochenek, G. Dercz, D. Oleszak, Arch. Metall. Mater. 56, 4, 1015-1020 (2011). [16] D. Bochenek, Z. Surowiak, J. Alloy. Compd. 480, 732-736 (2009). [17] Y. Xu, Ferroelectric materials and their applications, Elsevier, North – Holland, Amsterdam 1991. [18] R.D. Shannon, Acta Cryst. A 32, 751-767 (1976). [19] O. Raymond, R. Font, N. Juarez-Almodovar, J. Portelies, J.M. Siqueiros, J. Appl. Phys. 97, 084107, 1-8 (2005). [20] M. Kuwabara, J. Am. Ceram. Soc. 73, 5, 1438-1439 (1990). [21] L.B. Kong, J. Ma, Mater. Lett. 51, 95-100 (2001)

Crystallisation kinetics and magnetic properties of a Co-based amorphous alloy

Purpose: In the present paper, the kinetics of crystallization process and its correlation with magnetic properties of the Co80Si9B11 alloy was carefully examined. Design/methodology/approach: The following experimental techniques were used: X-ray diffraction (XRD), electrical resistivity in situ measurements (four-point probe), saturation magnetization in situ measurements (magnetic balance) and initial relative magnetic permeability measurements (Maxwell-Wien bridge). Findings: The investigations proved that thermal annealing of amorphous Co80Si9B11 alloy leads to a crystallization process and radical changes of magnetic properties. The activation energy of this process was determined as Ec=3.0±0.2 eV. Research limitations/implications: According to the results presented in the present paper the examined alloys can be used as a very good soft magnetic material. Originality/value: The best soft magnetic properties are observed in as quenched state

Magnetoimpedance effect in amorphous and nanocrystalline alloys based on iron

Purpose: The main purpose of the paper is to study magnetic, electrical and plastic properties of the selected group of amorphous alloys in the context of their application as magnetoimpedance sensors. Design/methodology/approach: The presented results were obtained by applying different magnetic methods (low field permeability measurements, magnetic relaxation, magnetization versus magnetic field, magnetization in saturation versus temperature, magnetoimpedance effect versus static magnetic field and/or frequency), resistivity versus temperature and Young’s modulus versus temperatures. Structural changes taking place in annealed samples were examined by making use of X-ray diffraction method and high resolution electron microscopy observations. Findings: It was shown that in all examined amorphous alloys soft magnetic properties can be enhanced by applying a suitable 1-h annealing at temperatures Top listed in Table 1. After annealing at this characteristic temperature magnetic permeability in relation to the as quenched state increases more than 20 times and non-contact magnetoimpedance effect (ΔZ/Z)ncmax is of the order of 104%. This effect can be explained based on the random anisotropy model supplemented by energy terms describing magnetoelastic energy and stabilization energy related to free volume content. For the alloys for which the optimized microstructure corresponds to the relaxed amorphous phase the plastic deformation corresponding to formation of brittle cracks is much higher than for the examined nanostructured alloys. In the frequency range from 700 kHz to 2 MHz magnetoimpedenace effect (ΔZ/Z)ncmax is approximately constant. Research limitations/implications: Searching of new soft magnetic materials in the group of amorphous alloys based on iron obtained by melt spinning can give a promising result. For example one can obtain very good soft magnets showing also good mechanical properties. Practical implications: Based on the presented results one can obtain very good soft magnetic material with low field relative magnetic permeability of about 16 000 (Fe74Cu1Zr3Si13B9). In the examined group of amorphous alloys the best candidate for magnetoimpedane sensor applications is the Fe75,75Ag0,25Nb2B22 alloy for which (ΔZ/Z)ncmax = 104% and plastic deformation εop=0.015. Silver as an alloying addition to the base Fe-Nb-B alloy significantly improves the alloy plasticity. Originality/value: It was shown that the examined amorphous alloys based on iron after applying a suitable thermal annealing can be used as promising materials for nagnetoimpedance sensors

Microstructure and properties of the ferroelectric-ferromagnetic PLZT-ferrite composites

The paper presents the technology of ferroelectric-ferromagnetic ceramic composites obtained from PLZT powder (the chemical formula Pb0.98La0.02(Zr0.90Ti0.10)0.995O3) and ferrite powder (Ni0.64Zn0.36Fe2O4), as well as the results of X-ray powder-diffraction data (XRD) measurement, microstructure, dielectric, ferroelectric, and magnetic properties of the composite samples. The ferroelectric-ferromagnetic composite (P-F) was obtained by mixing and the synthesis of 90% of PLZT and 10% of ferrite powders. The XRD test of the P-F composite shows a two-phase structure derived from the PLZT component (strong peaks) and the ferrite component (weak peaks). The symmetry of PLZT was identified as a rhombohedral ferroelectric phase, while the ferrite was identified as a spinel structure. Scanning electron microscope (SEM) microstructure analysis of the P-F ceramic composites showed that fine grains of the PLZT component surrounded large ferrite grains. At room temperature P-F composites exhibit both ferroelectric and ferromagnetic properties. The P-F composite samples have lower values of the maximum dielectric permittivity at the Curie temperature and a higher dielectric loss compared to the PLZT ceramics, however, the exhibit overall good multiferroic properties

Analysis of the nanocrystalline phase formation process in amorphous Fe-X-Si-B alloys

The process of nanocrystalline phase formation, affecting magnetic properties, in amorphous Fe78Si8 Bι4, Fe76 ΑI2 Si8 Β14 , Fe76 Cr2 Si8 B14 and Fe76 Mo2 Si8 B14 alloys has been studied in the paper. Investigations have been carried out using the electrical resistivity method, magnetic methods, transmission electron microscopy and X-ray diffraction. A nanocrystalline phase in the amorphous matrix has been obtained by isochronous or isothermal vacuum annealing. Phase composition of samples has been determined directly after manufacturing and after crystallization annealing on the basis of X-ray diffraction and electron diffraction. Transmission electron microscopy was used to determine phase morphology, dimensions of formed nanocrystalline phase and transition phase. Alloying elements have been found to affect changes of magnetic properties in amorphous and nanocrystalline states. For Fe76Mo2 Si8 Β14 alloys a significant increase in crystallization temperature, making difficult nanocrystalline phase growth and increase in thermal stability of magnetic permeability have been observed

Influence of heat treatment on changes on structure and magnetic properties of CoSiB alloy

Purpose: This paper describes influence of heat treatment on changes on structure and magnetic properties of the amorphous Co77Si11.5B11.5 alloy. Design/methodology/approach: The following experimental techniques were used: X-ray diffraction (XRD), static and dynamic measurements of magnetic properties (magnetic balance, fluxmeter, Maxwell-Wien bridge). Findings: The crystallization process involved by heat treatment leads to significant changes of structure and magnetic properties of amorphous Co77Si11.5B11.5 alloy. Research limitations/implications: Practical implications: The attractive properties of Co-Si-B alloy are of special interest for basic research on the materials as well as for their potential applications, like magnetic sensors. According to the results presented in this paper the examined Co77Si11.5B11.5 alloy as a soft magnetic material may be used in noise filters, saturable reactors, miniature inductance elements for abating spike noise, zero-phase current transformers, and magnetic heads etc., i.e. devices which are expected to exhibit high levels of permeability at high frequencies. Originality/value: It has been shown that thermal annealing at temperature close to the crystallization temperature leads to a significant increase of the initial magnetic permeability

Influence of copper addition on properties of (Fe36Co36B19Si5Nb4)100-xCux metallic glasses

Purpose: The main aim of the paper was investigation of influence of copper addition on thermal, magnetic and mechanical (microhardness) properties of (Fe36Co36B19Si5Nb4)100-xCux (x=0 and 0.6) metallic glasses. Design/methodology/approach: The following experimental techniques were used: differential thermal analysis (DTA), transmission electron microscopy (TEM) and X-ray diffraction (XRD) method, measurements of magnetic properties, Vickers microhardness. Findings: It was shown that addition of small amount of copper to the base alloy induced a change of thermal, magnetic and mechanical properties. Research limitations/implications: The relationship between structure and magnetic and mechanical properties can be useful for practical application of these alloys. Practical implications: The (Fe36Co36B19Si5Nb4)100-xCux (x=0 and 0.6) metallic glasses due to a unique properties have been commercialized in the following application fields: precision mould material, precision imprint material, precision sensor material, precision machinery material and surface coating material. Originality/value: The originality of the paper are examinations of changes of thermal and mechanical properties combined with magnetic properties of the (Fe36Co36B19Si5Nb4)100-xCux (x=0 and 0.6) metallic glasses