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[2024年12月号掲載 5_MT-M2024034.pdf](https://mdr.nims.go.jp/filesets/c905bb3f-72af-41aa-91c7-348524df3ce2/download)

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Yuya Chiba, Hiroaki Otsuka, Satoshi Amano, Junpei Inutsuka, Yuuji Iwasaki, Yasuhiko Inoue, Susumu Motomura, Atsumichi Kushibe, [Takahiro Sawaguchi](https://orcid.org/0000-0002-9405-002X), Terumi Nakamura

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[Development of Manufacturing Technology for Fe-Mn-Si Alloys with Excellent Low- Cycle Fatigue Properties and Application to Seismic Dampers for Buildings](https://mdr.nims.go.jp/datasets/f9c19137-246f-4f4e-9802-a1669e5a77ec)

## Fulltext

Development of Manufacturing Technology for Fe-Mn-Si Alloys with Excellent Low-Cycle Fatigue Properties and Application to Seismic Dampers for BuildingsDevelopment of Manufacturing Technology for Fe-Mn-Si Alloys with Excellent Low-Cycle Fatigue Properties and Application to Seismic Dampers for Buildings+1Yuya Chiba1,+2, Hiroaki Otsuka1, Satoshi Amano2, Junpei Inutsuka3, Yuuji Iwasaki4, Yasuhiko Inoue5,Susumu Motomura5, Atsumichi Kushibe5, Takahiro Sawaguchi6 and Terumi Nakamura71R & D Group, Awaji Materia Co., Ltd., Tokyo 101-0052, Japan2Steelmaking Technical Dept., Yamaguchi Works, NIPPON STEEL Stainless Steel Corporation, Hikari 743-8550, Japan3Plate Quality Control Dept., Yawata Works, NIPPON STEEL Stainless Steel Corporation, Kitakyushu 805-0058, Japan4Steelmaking Process Research & Development Div., Research & Development Center, NIPPON STEEL Stainless Steel Corporation,Hikari 743-8550, Japan5R & D Institute, Takenaka Corporation, Inzai 270-1395, Japan6Research Center of Structure Materials, National Institute for Materials Science, Tsukuba 305-0047, Japan7Business Department, The Japan Welding Engineering Society, Tokyo 101-0025, JapanThe Fe-15Mn-10Cr-8Ni-4Si alloy, which has excellent low-cycle fatigue durability, was developed as a core material for steel-basedvibration dampers that are effective against large-amplitude, long-period earthquake motions, and was put into practical use in 2014. However,manufacturing using small-scale equipment was expensive, so the authors tried manufacturing using stainless steel continuous casting facilityand rolling facility, and succeeded in mass production. The authors also developed welding materials and welding techniques to assemble abuckling restraint brace damper with flat plasticizing section and one with cruciform plasticizing section, and successfully put these two typesof brace dampers into practical use. The alloy plate has been recognized as an industrial product that can be manufactured with stable quality,and has been approved by the Minister of Land, Infrastructure, Transport and Tourism as a steel material for construction.[doi:10.2320/matertrans.MT-M2024034](Received March 27, 2024; Accepted September 26, 2024; Published October 11, 2024)Keywords: Fe-Mn-Si-based alloy, low-cycle fatigue property, continuous casting, brace damper, the approval by Minister of Land,Infrastructure, Transport and Tourism1. Background and Development HistoryNeedless to say, earthquake preparedness is important inJapan, a country with frequent earthquakes. As seismiccountermeasures for buildings, seismic dampers that suppressdamage to main structures by intensively undergoingdeformation during earthquakes, especially steel systemseismic dampers are often used from the viewpoint of cost,load capacity and productivity. In the Great East JapanEarthquake of 2011, long-period ground motions continuedin skyscrapers in the Tokyo metropolitan area far from theepicenter, and in the Kumamoto Earthquake of 2016, after-quakes of the same seismic intensity occurred the day afterthe earthquake of seismic intensity 7. Therefore, the demandfor steel dampers with excellent durability against repeatedelastoplastic deformation has increased.The authors developed Fe-15 Mn-10 Cr-8 Ni-4 Si alloy(mass%, thereafter FMS alloy), which drastically increasedthe low-cycle fatigue life by more than 10 times thanconventional steels, by utilizing the reversible transformationof deformation-induced martensite in Fe-Mn-Si system shapememory alloys [1]. In 2014, shear panel steel damperswithout welding structure using FMS alloy melted and rolledin a special steel manufacturing facility were applied to JPTower Nagoya [2]. However, this facility had a small meltingvolume of 10 tons, and it was difficult to manufacturewide rolled plates. Therefore, it was necessary to establish amanufacturing system using a continuous casting facility forstainless steels and a plate manufacturing facility as amanufacturing method capable of mass-producing widerrolled plates. In addition, in order to manufacture the mostgeneral buckling restraint brace damper whose plasticizedcross section is flat or cruciform as a vibration control device,it was essential to develop welding materials and weldingtechnology that enable welding between FMS alloy platesand ordinary architectural steel plates, and welding betweenFMS alloy plates to each other. It was also essential to obtainthe approval by Minister of Land, Infrastructure, Transportand Tourism (standard strength is 270N/mm2) for the rolledplates of the alloy in order to popularize it in the field ofconstruction.2. Production of FMS Alloy Rolled Plates fromContinuous CastingThe FMS alloy has a high Cr content of 10mass%, whichis close to that of stainless steel. However, there was no steeltype that contains a large amount of Mn and Si at the sametime. Therefore, the strength and ductility of FMS alloy aftermelting and solidification were examined in order to judgethe feasibility of continuous casting. As a result, it wasdetermined that it could sufficiently withstand pullout duringcasting, so it was melted and cast in a 60-ton stainless steelcontinuous casting facility, and rolled plates of 8 to 34mm inthickness © 1400 to 1600mm in width © 6 to 10m in lengthwere successfully manufactured within the plate thicknessstandards of JIS G 4304 (Fig. 1, Fig. 2). Table 1 showsexamples of the mechanical properties of typical rolled+1This Paper was Originally Published in Japanese in Bulletin of the JapanInstitute of Metals Materia Japan 63 (2024) 60–62.+2Corresponding author, E-mail: y.chiba@awaji-materia.co.jpMaterials Transactions, Vol. 65, No. 12 (2024) pp. 1583 to 1587©2024 The Japan Institute of Metals and Materials TECHNICAL ARTICLEhttps://doi.org/10.2320/matertrans.MT-M2024034plates, charpy absorbed energies and low cycle fatigue liveswith a strain amplitude of «1.0% [3].The low cycle fatigue lives of 13 rolled plates of FMSalloy prepared by this method at the strain amplitude «1.0%were 10,730 to 17,711 cycles (average 13,556 cycles), whichare equivalent to the fatigue lives of the same alloy preparedby a small amount of melting (several 10 kg).Low cycle fatigue tests were carried out on 23mm thickrolled plates manufactured at the same facility with strainvalues of «0.5 to «5.0%.On the high-strain side («2.0 to «5.0%), the radial straincontrol was performed using an hourglass-shaped specimento prevent the specimen from buckling, and on the low-strainside («0.5 to «2.0%), the axial strain control was performedusing a round bar specimen.When the horizontal axis is the strain amplitude ¦εt/2 andthe vertical axis is the life Nf, a straight line is plotted on adouble-logarithmic graph, and Manson-Coffin’s law holdsfor both conventional LY225 (low yield point steel) and FMSalloys. FMS alloys have approximately 10 times longerfatigue lives than LY225 steels up to a high strain of «5.0%(Fig. 3).As for the mechanical properties, as a result of theinvestigation of 59 rolled plates manufactured so far, it wasconfirmed that the average value of 0.2% proof stress in therolling direction is 286MPa, and that each data is normallydistributed in the range of approximately «3σ within thestandard value, and that it is possible to manufacture rolledplates with stable mechanical properties, and to manufactureproducts of stable quality as industrial products necessary forthe Minister of Land, Infrastructure, Transport and Tourism’scertification as designated building materials. Similar resultswere obtained for tensile strength and Charpy absorptionenergy.3. Development of Welding Technology and Productionof DampersBuckling restraint brace dampers, which are mostcommonly used as vibration control devices, have flat orcruciform plasticizing section. The respective designFig. 1 A FMS alloy continuous casting slab with 140mm in thickness,about 1300mm in width, about 10m in length.Fig. 2 A FMS alloy rolled plate with 22mm in thickness, about 1600mmin width, about 10m in length.Table 1 Mechanical properties and fatigue lives of FMS alloy plates produced from stainless steel continuous casting process.a T h e  s p e c i m e n s  w e r e  f a b r i c a t e d  i n  c o m p l i a n c e  w i t h  J I S  Z  2 2 4 1b U s i n g  s u b s i z e  s p e c i m e nFig. 3 Low cycle fatigue lives of FMS alloy plates in comparison withthose of LY225 steel.Y. Chiba et al.1584drawings are shown in Fig. 4 [4] and Fig. 5 [5]. In bothbraces, the core plate consists of a plasticizing section (centerparallel section) and joint sections (widening sections) at bothends. In the case of a flat plasticizing section brace, ribs ofstructural steel plates (SN 490 B) are fillet welded to thejoints. On the other hand, in a cruciform plasticizing sectionbrace, it is necessary to fillet weld core plates (FMS alloy) toeach other, and since the fatigue durability of the plasticizingsection is required similar to that of the core plate, the fatiguedurability of the welded part is required similar to that of theFMS alloy.The authors developed welding materials and weldingtechnology suitable for welding between the FMS alloy andthe ordinary architectural steel, and welding between FMSalloys to each other [6]. The former is required to be strongas a joint, the latter is required to follow plastic deformation,and both are required to prevent high-temperature crackingof the weld metal. The former is a weld material with acomponent such that the solidification mode of the weldmetal is the FA mode in which the primary ferrite crystallizes,the austenite crystallizes in the eutectic reaction, and thesolidification is completed in the two phases of ferrite andaustenite. As for the latter, while solidifying in the A mode,high-temperature cracking was successfully suppressed byoptimizing the welding conditions, and it became possibleto manufacture the core member of damper shown in Fig. 6(flat plasticizing section) and Fig. 7 (cruciform plasticizingsection), respectively.4. Loading Test of Actual-Scale Brace DamperThe cyclic loading test of the flat plasticizing section bracedamper shown in Fig. 4 was carried out using a uniaxialloading device with a maximum load capacity of 3000 kN ata strain amplitude of «0.5%, and the fatigue durability wasconfirmed. The test was carried out at a maximum loadingrate of about 1mm/sec with an upper limit of 1000 cycles,which is about twice the fatigue life of conventional steelbrace. As shown in Fig. 8, the change of the maximum loaddue to the repetition of the flat plasticizing section bracedamper is very gradual and has hardly changed up to 1000cycles, and it is confirmed that it has excellent durability andstability of the generated load [4, 7].Fig. 4 A design example of FMS alloy flat plasticizing section brace damper [4].Fig. 5 A design example of FMS alloy cruciform plasticizing section brace damper [5].Fig. 6 A Core member of a flat plasticizing section brace damper.Fig. 7 A Core member of cruciform plasticizing section brace damper.Running Head: Manufacturing Technology and Application of Fe-Mn-Si Alloys 1585Next, a low cycle fatigue test of the cruciform plasticizingsection brace damper shown in Fig. 5 at a strain amplitudeof «1.5% was carried out using the same machine as above.The change in the maximum load due to the repetition isshown in Fig. 9, and the fatigue life was 356 cycles (thenumber of cycles when the load decreased to 80% of themaximum load), which was more than 7 times the averagevalue of the conventional steel brace.5. Application Status16 flat plasticizing section brace FMS alloy dampers (corelength approx. 6m) with joints welded to structural steelwere mounted at the Aichi International Exhibition Center,completed in 2019 (Fig. 10) [8], and 32 cruciformplasticizing section brace dampers (core length 5³6m) withFMS alloys welded to each other were mounted at theChunichi Building, completed in 2023 (Fig. 11). In the lattercase, the maximum applied load was increased due to theincrease in the cross-sectional area, which contributed to thereduction in the number of installations compared with theconventional steel dampers [9].6. Material Approval, Patents, and New DevelopmentsIn recent years, due to the increase in the number ofapplications and the increase in the production results ofcontinuous casting, the authors applied for general materialcertification of this alloy, and in November 2022, the Ministerof Land, Infrastructure, Transport and Tourism approved itas a building material designated under Article 37 (ii) of theBuilding Standards Act (MSTL-0584, Reference value270N/mm2). As for the patents of this alloy, JapaneseNo. 6182725 and 6887642, European EP 2940175 andKorea 10-2144708 have been registered. For lens dampersµusing this alloy, Japan ERI Co., Ltd. issued a structuralperformance evaluation report (ERI-K 21006) [10], and inaddition, various types of vibration control dampers such asHourglass-shaped damper [11], H-section buckling restrainedbrace [12], and U-shaped damper [13] have been activelydeveloped.7. Summary, Future ProspectsIn order to popularize FMS alloys, which have aremarkable low cycle fatigue life of 10 times that ofconventional materials, as seismic dampers for long-periodground motions and large earthquakes, the authors estab-lished mass-production manufacturing technology for theplates, welding technology with ordinary architectural steel,and welding technology between FMS alloys, and obtainedthe approval by Minister of Land, Infrastructure, Transportand Tourism for the plates. As a result, constructioncompanies and designers can select various types of seismicdampers such as shear panel type and brace type using FMSalloy. In the future, it is expected that not only large braceFig. 8 Change of the maximum load due to the repetition of the flatplasticizing section brace damper at a strain amplitude of «0.5% (The testwas completed after 1000 cycles) [4].Fig. 9 Change of the maximum load due to the repetition of the cruciformplasticizing section brace damper at a strain amplitude of «1.5% [5].Fig. 10 Flat plasticizing section FMS alloy brace dampers mounted at theAichi International Exhibition Center.Fig. 11 Cruciform plasticizing section FMS alloy brace dampers mountedat the Chunichi Building.Y. Chiba et al.1586dampers for skyscrapers, but also panel dampers for mid- andlow-rise buildings, condominiums, and general housing willbe widely used. Moreover, it is expected that they will beused for civil engineering, bridges, and other industries.REFERENCES[1] T. Sawaguchi, I. Nikulin, K. Ogawa, K. Sekido, S. Takamori, T.Maruyama, Y. Chiba, A. Kushibe, Y. Inoue and K. Tsuzaki: DesigningFe–Mn–Si alloys with improved low-cycle fatigue lives, Scr. Mater. 99(2015) 49–52.[2] T. Sawaguchi, T. Maruyama, H. Otsuka, A. Kushibe, Y. Inoue and K.Tsuzaki: Design Concept and Applications of Fe–Mn–Si-BasedAlloys—from Shape-Memory to Seismic Response Control, Mater.Trans. 57 (2016) 283–293.[3] H. Otsuka, Y. Chiba, T. Sawaguchi, S. Takamori, A. Kushibe, K.Umemura and Y. Inoue: JIMM’s fall annual meeting, (2018) J76.[4] K. Umemura, A. Kushibe, Y. Inoue, Y. Mizushima, H. Otsuka, Y.Chiba, T. Nakamura and T. Sawaguchi: Summaries of TechnicalPapers of Annual Meeting AIJ, (2018) pp. 731–732.[5] F. Osuga, K. Kawato, A. Kushibe, Y. Inoue, S. Motomura, T. Ishida, S.Tsurugano and K. Umemura: Summaries of Technical Papers ofAnnual Meeting AIJ, (2020) pp. 943–944.[6] T. Nakamura and T. Sawaguchi: J. Struct. Eng. 67B (2021) 633–641.[7] Architectural Institute of Japan (AIJ): Recommended Provisions forSeismic Damping Systems applied to Steel Structures, (2014) pp. 37–38.[8] A. Kushibe, Y. Inoue, K. Umemura, T. Nakamura, T. Sawaguchi, H.Otsuka and Y. Chiba: Welding Technol. 68 (2020) 60–66.[9] Takenaka Corporation News Release September 26, (2023).[10] Lens Damper Promotion Council News Release September 2, (2022).[11] T. Iida, T. Kinoshita, Y. Inoue, A. Hanai, Y. Kurokawa, S. Motomura,T. Sone and M. Yamamoto: Summaries of Technical Papers of AnnualMeeting AIJ, (2021) pp. 523–524.[12] Y. Inoue, K. Kawato, S. Yoshino, S. Motomura, K. Umemura and A.Kushibe: Summaries of Technical Papers of Annual Meeting AIJ,(2023) pp. 315–316.[13] K. Sakamoto, T. Abe and M. Kubota: Summaries of Technical Papersof Annual Meeting AIJ, (2023) pp. 319–320.Running Head: Manufacturing Technology and Application of Fe-Mn-Si Alloys 1587https://doi.org/10.1016/j.scriptamat.2014.11.024https://doi.org/10.1016/j.scriptamat.2014.11.024https://doi.org/10.2320/matertrans.MB201510https://doi.org/10.2320/matertrans.MB201510