24-CHROMIUM FERRITIC STEEL MAGNETIC PROPERTIES. A 24-chromium ferritic stainless steel had been made by foundry methods. The purpose of this investigation is to investigate the magnetic behavior of this ferritic sample, as one of the divvy of its characteristics. Some of supporting data used to prove that the material sample was ferritic type and followed by hysteresis curve obtained from the experiment. By Vibrating Sample Magnetometer (VSM) equipment, it is found that the ferritic steel has the saturation induction around of 150 emu g-1, with the coercive force Hc is close to 3 x 10-4 T and the remanent induction Br is close to 1,1 x 10-3 emu g-1 meanwhile by permagraph equipment the saturation induction around of 3.13 kG, and the coercive force HcB is equal to 0.005 kOe and the remanent induction Br is 0.23 kG with the dissipasion energy BHmax zero, explains that the ferritic stainless steel has a relative good magnetic behavior with relative high magnetization at the relative weak external magnetic field and can be demagnetized easily, appropriate to soft magnetic materials

Darwinto, Tri

Effendi, Nurdin

Ismoyo, Agus Hadi

Parikin, Parikin

Badan Tenaga Nuklir Nasional: Jurnal BATAN

18724-Chromium Ferritic Steel Magnetic Properties (Nurdin Effendi)Akreditasi LIPI No.: 395/D/2012Tanggal 24 April 2012ISSN: 1411-1098Homepage: http://jusami.batan.go.idJurnal Sains Materi Indonesia24-CHROMIUM FERRITIC STEEL MAGNETIC PROPERTIESNurdin Effendi, Tri Darwinto,Agus H.I. and ParikinCenter For Science and Technology of Advanced Materials-Indonesian National Nuclear Energy AgencyKawasan Puspiptek, Serpong, 15314, Tangerang Selatane-mail: nurdineffendi@yahoo.comDiterima: 25 Nopember 2013 Diperbaiki: 10 Maret 2014 Disetujui: 16 Mei 2014ABSTRACT24-CHROMIUM FERRITIC STEEL MAGNETIC PROPERTIES. A24-chromium ferritic stainlesssteel had been made by foundry methods. The purpose of this investigation is to investigate the magneticbehavior of this ferritic sample, as one of the divvy of its characteristics. Some of supporting data used toprove that the material sample was ferritic type and followed by hysteresis curve obtained from the experiment.By Vibrating Sample Magnetometer (VSM) equipment, it is found that the ferritic steel has the saturationinduction around of 150 emu g-1, with the coercive force Hc is close to 3 x 10-4 T and the remanent induction Bris close to 1.1 x 10-3 emu g-1 meanwhile by permagraph equipment the saturation induction around of 3.13 kG,and the coercive force HcB is equal to 0.005 kOe and the remanent induction Br is 0.23 kG with the dissipasionenergy BHmax zero, explains that the ferritic stainless steel has a relative good magnetic behavior with relativehigh magnetization at the relative weak external magnetic field and can be demagnetized easily, appropriate tosoft magnetic materials.Kata kunci: Ferritic, Steel, Magnetic, Remanent induction, Coercive forteABSTRAKSIFAT MAGNETIK BAJA FERITIK 24-KROMIUM. Telah dibuat baja feritik 24-kromium denganmetode pengecoran. Tujuan investigasi ini untuk mengetahui perilaku magnet sampel baja feritik ini yangmerupakan bagian dari karakteristik baja ini. Sebagian data dukung digunakan untuk membuktikan bahwasampel yang digunakan adalah jenis feritik dan kurva histerisis yang diperoleh dari percobaan. Dengan alatVibrating Sample Magnetometer (VSM), diperoleh bahwa feritik ini memiliki induksi saturasi sekitar150 emu g-1, dengan gaya koersif Hc mendekati 3 x 10-4 T dan induksi remanen sekitar 1,1 x 10-3 emu g-1sedangkan dengan alat permagraf nilai induksi saturasinya sekitar 3.13 kG, dan gaya koersif HcB 0.005 kOe daninduksi remanen Br 0,23 kG dengan energi desipasi BHmax nol menunjukkan bahwa baja feritik ini memilikiperilaku magnet yang relatif baik dengan magnetisasi yang tinggi pada medan magnet eksternal yang relatiflemah dan dapat didemagnetisasi dengan mudah, cocok untuk bahan magnet lunak.Keywords: Feritik, Baja, Magnetik, Induksi Saturasi, Gaya koersifINTRODUCTIONA 24-chromium ferritic stainless steel had beenmade by foundry methods utilizing the local miningproducts as starting materials [1-3]. The purpose of theferritic sample synthesis is to investigate magneticbehavior of very high chromium ferritic steel and thepotential used for many applications [4]. High chromiumcontent of ferritic steel is proposed because of its highcorrosion resistant characteristic in various corrosiveenvironment. According to magnetic behaviorclassification, ferritic stainless steels are classified asferromagnetic and because they are easy to magnetizeand demagnetize, they are called soft magnetic materials[5]. They have been used as soft magnetic componentsin such devices as electromagnets, transformer, inductorcores operating up to high a.c. frequencies, pole piecesand return paths. Although their magnetic propertiesare not generally as good as conventional soft magneticalloys, they are successfully used for magnetic188Jurnal Sains Materi Indonesia Vol. 15, No. 4, Juli 2014, hal. 187-191components which must withstand corrosiveenvironments. As such, they offer a cost-effectivealternative to plated iron and silicon-iron components.In addition, the relatively high electrical resistivity offerritic stainless steels has resulted in superior ACperformance. The ferritic stainless steels have softmagnetic properties: high magnetic permeability, lowcoercive force Hc, and low residual induction Br,which depend on alloy chemistry [5, 6]. In particular,impurities such as carbon, sulfur, and non-metallicinclusions, and stresses are present in the materialbecause of cold working; with increasing amounts ofimpurities and stress, the magnetic permeabilitydecreases and the coercive force Hc increases, so thebehavior is less magnetically soft.  Hence, optimummagnetic performance is obtained with high-purity alloysand well-annealed [7, 8]. When heated, ferromagneticmaterials become paramagnetic at a temperature knownas the (ferromagnetic) Curie point [9]. So it can be saidthat in many ferromagnetic materials the magneticproperties depend greatly on the effect of impurity,previous history state of strain, size, perfection andorientation of crystals, and temperature [3, 8, 9, 10]. Thecondition of the sample composition according to themeasurement result by Optical Emission Spectroscopy(OES) methods in Bandung Manufacture Poly-technique[1] is tabulated in Table-1.THEORETICAL BACKGROUNDWhen a material is in a magnetic field Hi with themagnetization (or dipole moment per unit volume) Mi,the magnetic induction in the material Bi is given byBi =o(Hi + Mi) =or Hi = Hi .................... (1)where o = 4x 10-7AmTis free space permeability, r isthe material relative permeability (= 1 for vacuum),a dimensionless quantity, and the i superscript is vectorscontravariant index. The relative permeability is ameasure of the intensity of the induced magneticfield. Hencer = 1 + iHM i= 1 +  ............................... (2)where  is magnetic susceptibility. Hi, Mi and Bi arevectors; the unit of Bi is tesla or 2mweber, while Hi and Mihave the same units of mA. To guarantee the validity ofequation (1), it is more save if the relation formula inequation (1) is written in the form ofBi =ijHj ........................................................ (3)where now the material permeability is in the tensorform, to hold if the magnetic induction (Bi) direction isdifferent from the external magnetic (Hj) direction,where j-subscript in Hj magnitude is covariance index.This is particularly in connection with the magneticdomain and the magnetic domain wall which can turnthe magnetic induction direction.The energy is dissipated when the hysteresis loopis traversed in the counterclockwise direction and thework done by the loop areaP =  Bd.Hμ1o......................................... (4)and the loop integral values in equation (4) isproportional to the area found within the B-Hhysteresis curve.EXPERIMENTThis section explains about the procedure ofmaterial measurement by vibrating sample magnetometerin the ferritic sample magnetic properties investigationin the laboratory; the explanation involving othermeasurement data, including the micro structure and theX-ray diffraction data which were carried out before wasreported elsewhere [1].Sample preparationFirst the ferritic stainless steel bulk was slicedinto several thin pieces of steel by a disc blade apparatus.Then the thin pieces of steel were again cut into smallerslices, but this time perpendicular to the first slice insuch a manner that now the maximum areal dimension ofaround 2 x 2 mm2was obtained. Finally the samples wereweighed in a high-precission balance scales and thesamples mass was found to be equal or less than60 mg; but it is better if the mass is around of 40 mg. Thefinal form of the sample is cubic grain with the 1 x 1 mm3size and around of 60 mg maximum weight.Hysteresis MeasurementThe instrument employed in the hysteresismeasurement is the Vibrating Sample Magnetometer(VSM), manufactured by the German OxfordEnterprise Co.A piece of steel sample with the specified massand dimension mentioned above was inserted into theVSM sample holder and the measurement was thencarried out at the following measurement conditions,the measurement temperature is 296 K, the vibrationTabel 1. Chemical composition of the sample.Element Cr Mn Si C Ti Al P SQuantity(%) 23.711 0.821 2.02 0.258 0.006 0.007 0.022 0.01418924-Chromium Ferritic Steel Magnetic Properties (Nurdin Effendi)frequency was 55 Hz, with an external magnetic fieldvaried in the range of 0 – 1 T. The result is plotted to beBH hysteresis curve.Another hysteresis measurement was carried outby the permagraph equipment in the Electronics andTelecommunication Research Center, Indonesian ScienceInstitute (PPET-LIPI) in BandungRESULTAND DISCUSSIONIn order to confirm that the synthesized24-chromium ferritic stainless steel sample is of theferritic type, first the sample optical microgram will beshown followed by the x-ray diffraction patterns. Thesample microgram with the magnification of 100 is shownin Figure 1, and depicts the ferritic type material grains,where the grain boundaries are found to consist ofirregular spasmodic arch path fragments and this is thetypical ferritic type material grain boundaries. Meanwhileit is common knowledge that the austenitic type grainboundaries consist of straight line fragments.The X-ray intensity pattern of the sample wasrecorded with an automated Shimadzu X-raydifractometer using Cu K radiation by measuring thediffraction angle (2) between 40 and 120 using thestep-scan method with an increment of 0.05 with thetime counting 10 seconds. It is easily observed from theX-ray patterns that the characteristic signature peaks,i.e. 110, 200, 211, 220, 310, are clearly identifiable in thesamples as shown in Figure 1. These diffraction peaksof the foundry synthesized F1 ferritic steel are in excellentagreement with those reported in literature thereforeconfirms the BCC model of the sample’s crystal structureand immediately confirms the ferritic characteristicstructure of the sample.The measurement result from VSM equipment isshown in Figure 3, that depicts the the ferritic stainlesssteel B-H or hysteresis curve. In this picture the top partcurve line is shown to be almost paralel to and also tooverlap with the bottom part curve line. From the curveit is also visible that the value of the saturation inductionreached is relative high, around of 150 emu g-1 that ifconverted [11], it is equal to around 1.5 T at magneticfield Hi strength of around of 1 Am-1. Therefore byequation (1) and the conversion factor it could becalculated that the materials relative permeability r is11.9366 x 105 m3 kg-1, meanwhile the materials magneticsuseptibility  is around minus one as estimated fromthis value. From the curve it is also visible that thecoercive force Hc is close to the origin point, as is theremanent induction, Br , and from the experiment datavalue both . of the coercive force Hc -3 x 10-4 T and theremanent induction value Br  1.1 x 10-3 emu g-1respectively. These results also can be looked atTable 2, where the units were converted to Gauss (G)and Oerstedt (Oe), and it could be said that both of thecoercive force Hc and the remanent induction value Brrespectively are very small. From this point of view itcould be immediately corroborated that the area boundedby the curve lines is very thin or very small, and is almostinvisible, so that the work done by the loop integralwhich is related to the dissipation energy is alsopractically close to zero, and this result is suittable withthe result of permagraph measurements (Table 3) wherethe value of BHmax is equal to zero (0 MGOe). Thereforefrom this point of view it could be argued that theferritic stainless steel sample is both easily magnetizableand demagnetizable in a relatively weak externalmagnetic field.Figure 1. The 24-chromium ferritic type stainless steelmicro structure, 100 x magnificationFigure 3. Hysteresis curve of the 24-chromium ferriticstainless steel found by VSM equipmentBr (kG) HcB (Oe) Hmax (kOe) (k emu g-1 Oe-1)0.11 3.8 0.00004 95Table 2. Parameter values from VSM measurement resultFigure 2. X-ray diffraction pattern of the 24-chromiumferritic type stainless steel190Jurnal Sains Materi Indonesia Vol. 15, No. 4, Juli 2014, hal. 187-191Meanwhile, the B-H curve from permagraphmeasurement result is shown in Figure 4. The red curveis external magnetic used, meanwhile the blue one is theinternal respons induction from material (sample). Besidethis curve it is also attached the some parameters valuesof the measurement as shown in Table 2 meanwhile Table3 below shows the magnetic field strength (H) versusthe magnetic polarization (J), and averagely it is appearthat the curve is very thin and it is consistent with thethat of VSM measurement result and the Table 3 andTable 4 elucidate this.From Table 3 can be looked that the remaneninduction magnet Br is equal to 0.23 kG, a relative smallvalue, and the induction coercivitas force (HcB) is equalto 0.005 kOe, meanwhile the polarization coercivitas force(HcJ) is equal to 0.007 kOe, the value that is very small.Meanwhile another magnitude parameters can be lookedfrom Table 2; here Ba symbol is the magnetic flux,meanwhile the Ha symbol is the field strong at themaximum dessipation energy.From Table 4 also can be looked that the magneticpolarization component (J) is equal to zero, and it is meanthat there is no polarization contribution to the materialmagnetic respons.Especially for coersive force Hc, this parametercan be compared to the literatur for some data ofstandard ferritic stainless steels [12] that can be lookedat Table-5 below. Due to lack of data, another magneticparameter magnitudes as well as Br not found yet. Sofrom Table-5, it is found that the coersive force magnitudeof the 24-chromium ferritic stainless steels is still hassmall value close to the some standard ferriticmaterials, and has better value for measurement withVSM instrument.Although the sampel form in experiment byVSM and the permagraph is different, but the curveform that is very thin resulted by both of experimentis still consistent, with relative high magnetic moment;both of experiment results show that the energydissipation is very small close to zero, so that thematerial magnetic properties is suitable to softmagnetic properties.CONCLUSIONFrom the experimental results and the discussionabove it can be concluded that the the 24-chromiumferritic stainless steel has a relative good soft magneticproperties; it can become very strongly magnetized in arelative weak external field and simultaneously could alsoeasily be demagnetized, and by the very thin curve form,it is mean that the energy dissipation is very small, closeto zero. The measurement from both apparatus, VSMand also permagraph gives the consistence results.Conclusively, this material is appropriate to be used asa soft magnetic material and hence it can be used as asubstitute for conventional soft magnetic materials.REFERENCE[1]. T. Darwinto andA. K. Jahja, “Analisis Strukturmikrodan Struktur Kristal Feritik F1”, Jurnal SainsMateri Indonesia, vol. 11, no. 3, pp. 202-206, 2010.[2]. N. Effendi, “Austenitic Type Stainless SteelProduction By Foundry Technology”, JurnalUrania, vol. 16, no. 2, pp. 69-77, 2010.[3]. K. H. Lo, C. H. Shek, and J. K. L. Lai, “Recentdevelopments in stainless steels,” Mater. Sci. Eng.R Reports, vol. 65, no. 4-6, pp. 39-104, May 2009.Figure 4. Hysteresis curve of the 24-chromium ferriticstainless steel by permagraph measurements. The redcurve is external magnetic, meanwhile the blue one is theinternal respons induction1 2 3 4Br (kG) HcB (kOe) HcJ (kOe) BHmax (MGOe)0.23 0.005 0.007 0.005 6 7Ha (kOe) Ba(kG) H max (kOe)0.560 3.13 14.065Table 3. Parameters values from the permagraph measurementresultH (kOe) -20 -40 -60 -80 -100 -120 -140J (kG) 0.0 0.0 0.0 0.0 0.00 0.00 0.0Table 4. H-J measurements result values, where J is the magneticpolarizationTable 5. Some Hc value of standard feritic stainless steelsCoersive Force, HcNo. MaterialsOe A m-11 AISI-430F 2 1602 AISI-430FR 2 1603 AISI-446 4.5 3604 24-chromium ferritic SSsample (VSM)0.4 325 24-chromium ferritic SSsapmle (Permagraph)5 40019124-Chromium Ferritic Steel Magnetic Properties (Nurdin Effendi)[4]. K. A. Cashell and N. R. Baddoo, “Ferritic stainlesssteels in structural applications,” Thin-WalledStruct., vol. 83, no. 0, pp. 169-181, Oct. 2014.[5]. H. R. Lashgari, D. Chu, S. Xie, H. Sun, M. Ferry,and S. Li, “Composition dependence of themicrostructure and soft magnetic properties of Fe-based amorphous/nanocrystalline alloys: Areviewstudy,” J. Non. Cryst. Solids, vol. 391, no. 0, pp.61-82, May 2014.[6]. T. Ceccon, P. Belloli, and P. Ramina, “The MagneticProperties ofA Precipitation Hardening and AsoftMartensitic Stainless Steel,” in Stainless Steel ’05- Proceedings of The 5th European CongressStainless Steel Science and Market, pp. 185-192,2005.[7]. V. B. Oliveira, M. J. R. Sandim, D. Stamopoulos,R. A. Renzetti, A. D. Santos, and H. R. Z. Sandim,“Annealing effects on the microstructureand coercive field of two ferritic–martensiticEurofer steels: A comparative study,”J. Nucl. Mater., vol. 435, no. 1-3, pp. 189-195,Apr. 2013.[8]. P. Oxley, J. Goodell, and R. Molt, “Magneticproperties of stainless steels at room and cryogenictemperatures,” J. Magn. Magn. Mater., vol. 321,no. 14, pp. 2107-2114, Jul. 2009.[9]. Y. Kudo, T. Sawai, S. Sakurai, K. Masaki, Y. Suzuki,T. Sasajima, T. Hayashi, R. Takahashi, M. Honda,S. Jitsukawa, and N. Miya, “Fabrication of 8Cr-2WFerritic Steel Tile for Reduction in ToroidalMagnetic Field Ripple on JT-60U,” J. Korean Phys.Soc., vol. 49, p. 297, 2006.[10]. W. Ding, L. Jiang, Y. Liao, J. Song, B. Li, and G. Wu,“Effect of iron particle size and volume fraction onthe magnetic properties of Fe/silicate glass softmagnetic composites,” J. Magn. Magn. Mater., vol.378, no. 0, pp. 232-238, Mar. 2015.[11]. B. M. Moskowitz, “Fundamental PhysicalConstants and Conversion Factors,” in GlobalEarth Physics,American Geophysical Union, 1995,pp. 346-355.[12]. Carpenter, “Alloy Techzone: Magnetic Propertiesof Stainless Steels,” Carpenter Technical Articles,2006.

24-CHROMIUM FERRITIC STEEL MAGNETIC PROPERTIES

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24-CHROMIUM FERRITIC STEEL MAGNETIC PROPERTIES

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