Flash butt welding of high manganese steel crossing and carbon steel rail

  • Published on
    21-Jun-2016

  • View
    226

  • Download
    3

Transcript

Materials Science and Engineering A 454455 (2007) 288292Flash butt welding of high manganese steel co Hechnoiverser 20AbstractThis study rossitwo-phase s nectone is the w s thamechanical eanfor the pract ary ito jetting wa ansfoannealing tr the bof the carbo n, whthus enhanc dingrail via the a 2006 ElseKeywords: Flash butt welding; Crossing; Rail; Microstructure1. IntroductionModernout any mtogether. Tused to chamade of auand generaAt preseable includrail steel isHowever, wbecause usganese (ZG(1114 wt%steel whichinvolves jotwo materi CorresponScience and TE-mail adtures and responses of welding behavior. Compared with the rail0921-5093/$doi:10.1016/jrailways in China demand the fully welded rails with-echanical joint, i.e. rails and crossings are weldedhe crossing is very important for the railways as it isnge the moving direction of the train. It is usuallystenitic high manganese steel and its actual geometryl dimensions are shown in Fig. 1.nt, the welding technology of railrail joints is avail-ing the welding of similar materials, even if thehigh carbon steel containing about 0.8% carbon.elding the crossing to the rail is rather difficult,ually the crossing is made of the Hadfield high man-Mn13) steel which contains C (1.11.4 wt%) and Mn), while the rail is made of the high carbon (U71Mn)contains C (0.60.8 wt%) and Mn (1.02.0 wt%) andining the dissimilar materials together. Moreover, theals exhibit different physical properties, microstruc-ding author at: State Key Laboratory of Metastable Materialsechnology, Qinhuangdao 066004, China. Fax: +86 335 8063949.dress: zfc@ysu.edu.cn (F. Zhang).steel, the high manganese steel has a lower heat conduction coef-ficient, a lower melting temperature and a higher heat expansioncoefficient.It is well known that welding high manganese steel is difficult,because carbide precipitation on austenitic grain boundaries inthe HAZ of the welded joint degrades the mechanical proper-ties, especially toughness and strength [1]. Fast cooling rate afterwelding can suppress the carbide precipitation in the high man-ganese steel. However, if the cooling rate is too fast after weldingthe high carbon steel, martensitic transformation will take placein the HAZ, which can lead to a decrease of the toughness inthe welded joint. Therefore, gradual cooling rate is desired afterwelding the high carbon steel.Nowadays, the technology to weld the high manganese steelcrossing to the high carbon steel rail can only be used in a fewcountries of the world. The first person who got a patent for it in1977 was an American [2]. He presented his method by weld-ing the crossing consisting of wear-resistant austenitic Mn steelcasting to the rails of C steel with the aid of an interposed con-nector consisting of austenitic low-C steel. In 1987, Bartoli andDigioia also got the welding technology of the high manganesesteel crossing and the carbon steel rail [3]. They realized that the see front matter 2006 Elsevier B.V. All rights reserved..msea.2006.11.018Fucheng Zhang a,b,, Bo Lv a, Baitaa State Key Laboratory of Metastable Materials Science and Tb College of Materials Science and Engineering, Yanshan UnReceived 14 July 2006; received in revised form 4 Novembsets out to introduce the flash butt welding of high manganese steel ctainless steel insert. There are two flash butt welded joints for the conelded joint of the carbon steel and the stainless steel, and the other iproperties and the microstructures of the welded joint are studied by mical rail. There is no carbide precipitation on the austenitic grain boundter cooling after the flash butt welding, and there is no martensitic treatment by a special induction heat treatment device, which will avoidn steel rail and the stainless steel insert is annealed at 900 C for 10 mie the strength of the welded joint. It is indicated that the flash butt welusteniteferrite two-phase stainless steel insert is feasible.vier B.V. All rights reserved.rossing and carbon steel railu b, Yanguo Li blogy, Qinhuangdao 066004, Chinaity, Qinhuangdao 066004, China06; accepted 6 November 2006ng and carbon steel rail by employing an austeniteferriteion of the high manganese steel and the carbon steel rail,t of the high manganese steel and the stainless steel. Thes of static bending, three bend-fatigue and metallographicn the HAZ of the high manganese steel crossing subjectedrmation in the HAZ of the carbon steel rail subjected torittleness of the welded joint effectively. The welded jointich will release the residual stress of the welded joint andof the high manganese steel crossing and the carbon steelF. Zhang et al. / Materials Science and Engineering A 454455 (2007) 288292 289anese steel crossing and (c) stainless steel insert.crossing-toflash butt wrail, thus elconnectingfor conneccasting witan aluminoBlumauer,[5]. His paway joint cof austenitithe rail madrial made oof low carbstabilized wIn 1994,ing a mangthe steps oend of the cpart. This mmon crossimethod of cThe weldinby weight,manganese0.400.70%0.13% of v0.045% of0.015% of pthen on, fewIn this sphase staintechnologyto the highmechanicathe tensile sthe three-pof the weld2. Experim2.1. MaterTable 1investigatecarbon steeing and thecrossing anal composition of steels investigated (wt%)C Mn Cr Ni Mo Si S Pnganese steel 1.2 13.4 0.53 0.025 0.031rbon steel 0.78 1.5 0.43 0.021 0.022s steerderlowistainhurcauswillerritse dored dysicexpave tocanBecaert mal md coormaldeded ainsehicateriin Tng intechnology of casting which can produce a high density. The mechanical and physical properties of the steelsgated are shown in Table 2. All the experimental data ofical properties of steels testedHigh carbonsteelHigh manganesesteelStainlesssteelFig. 1. Schematic of crossing: (a) high carbon steel rail, (b) high mang-rail connection by inserting an adapter casting waselded, first to the crossing and then to the carbon steeliminating the mechanical discontinuity between theparts. In 1988, an American Patent named Processting frogs consisting of austenitic manganese steelh rails consisting of carbon steel was applied forthermic welding [4]. In 1991, an Austrian worker,got another patent for the Mn steel crossing weldingtent presented a method of the connection of rail-omponents, that is, welding the crossing consistingc cast high manganese steel or the Mn steel rail ande of carbon steel by the utilization of an insert mate-f low-C austenitic steel. The insert material consistedon, austenitic steel, and in particular a CrNi steel,ith niobium and/or titanium.Alisay and co-workers reported a method of connect-anese steel part to another carbon steel part includingf depositing an austeno-ferritic stainless steel at thearbon steel part and welding it to the manganese steelethod was being applied to assemble a rail to a com-ng railway track part [6]. In 2002, Cerny invented aonnecting manganese steel with a rail of carbon steel.g material had the following composition in percentexcept for iron, 0.070.15% of carbon, 0.501.20% of, maximally 0.50% of silicon, 1.202.00% of chrome,of molybdenum, 2.503.50% of nickel, maximallyanadium, maximally 0.05% of titanium, maximallythe total contents of aluminum in steel, maximallyhosphor and maximally 0.015% of sulphur [7]. Fromwelding technologies were published [812].tudy, the authors employ an austeniteferrite two-less steel manufactured by a most precise castingto weld the high manganese steel crossing directlycarbon steel rail through the flash butt welding. Thel properties of the welding joint are measured, such astrength, the impact toughness, the static bending andoint-bend-fatigue strength. And the microstructuresing joint are studied through the optical microscope.ental proceduresTable 1ChemicSteelHigh maHigh caStainlesIn othe folphaseof sulpeasilywhich[13]. Fite phais desiThe phpoint,on, hawhichlower.the insmateriing antransfothe weannealThesteel, wnew mshowninsertiprecisecastinginvestiTable 2MechanPropertyialshas given the chemical composition of the materialsd. The composition of high manganese steel and highl is the standard composition of the Mn steel cross-carbon steel rail. In fact, the high manganese steeld the carbon steel rail are both commercial ones.Strength (MPToughness (J/Melting pointHeat expansio(m/(m K)Heat conduct(W/(m K))l 0.10 5.2 19.3 6.8 2.0 0.32 0.022 0.020to weld them together, the insert material has to haveng characteristics. (1) It is an austeniteferrite two-less steel with about 20% ferrite. As the compoundand phosphorus on the austenitic grain boundary cane the liquid crack in the welded joint of stainless steel,lose the mechanical properties of the welded jointe phase can fuse more S and P elements than austen-es [14], and ferrite phase as prior solidification phaseuring the solidification of the welded fusion [15]. (2)al properties of the insert material, such as meltingnsion coefficient, heat conduction coefficient and soapproximate to those of the high manganese steel,ensure that the residual stress of the welded joint isuse the welded joint of the high manganese steel andaterial is not annealed after welding. (3) The insertust not bring the phase transformation during heat-ling, especially carbon precipitation and martensitiction. In order to release the residual stress of welding,joint of the insert material and carbon steel has to befter welding.rt material is an austeniteferrite two-phase stainlessh contains 80% austenite and 20% ferrite, and as aal designed by the authors, its composition has beenable 1. The austeniteferrite two-phase stainless steelthe rail section shape is manufactured by a mosta) 865 882 643cm2) 22 215 288(C) 1485 1390 1440n coefficient)11.1 19.7 19.2ion coefficient 60.4 21.9 22.8290 F. Zhang et al. / Materials Science and Engineering A 454455 (2007) 288292Table 3Parameters used for the flash welding of carbon steel and high manganese steelrailsJunction Flashingspeed(mm/s)Upsettingspeed(mm/s)Flashingtime (n)Upsettingforce(MPa)Carbon steel andstainless steel5 100 12 180Stainless steel and highmanganese steel8 120 8 280Flashing and upsetting speeds are the moving ones of the welding part in theflashing and upsetting stages, respectively, upsetting force is the applied forcebetween two welding parts during the upsetting stage of the welding.the mechantested.The melsion coeffic22.8 W/(mhigh mangaganese stee19.7m/(mof heat con2.2. WeldinA modeSwitzerlanrail and thbutt weldinting. The flTable 3. Th(1) the welabout 350 rail was thtwo-phaseof about 2cial inductto the higoperation.2.3. MechaThe genexamined bequipmentsFig. 3. Schemata of bend and bend-fatigue tests.shown in Fig. 2. As is shown in Fig. 3, model JW-300 bend testequipment is employed to examine the bend strength and thebend camber of the welded joint of the high manganese steelcrossing and the carbon steel rail. It is a special three-point-est dactic200e thial tstremm.theoftestintancs theandt proicroming a-250e thC Xl-bea mprovhichicaloff thi.ical properties are the average value of ten samplesting point of the stainless steel is 1440 C, heat expan-ient 19.2m/(m K) and heat conduction coefficientK). Its physical properties are similar to those of thenese steel, as the physical properties of the high man-l casting normally contain 1390 C of melting point,K) of heat expansion coefficient and 21.9 W/(m K)duction coefficient.g procedurel GAAS 80/700 flash welding equipment made ind is used to carry out the welding of the carbon steele high manganese steel crossing. Usually the flashg procedure includes two stages, flashing and upset-ash welding parameters for this study are given ine welding is carried out in the following sequences:ded section of the carbon steel rail is preheated toC by an oxygenacetylene flame. The carbon steelen welded to the insert (e.g. the austeniteferritestainless rail). (2) Cut off the insert into a length0 mm. (3) The welded joint is annealed by a spe-ion heat treatment device. (4) The insert is weldedh manganese steel crossing in a second weldingnical properties of welded jointeral mechanical properties of the welded joint arey means of the conventional tensile and impact test. The position of the samples in the welded joint isbend tthe prZDMHexamina specfatigueis 500wards,middlewhenthe disthem isimilarthe tesChina.2.4. MTheby usiD/maxanalyz2500/Pparallein halfdard,1.5, wgeologsourceage o20 mAFig. 2. Sample positions in welded joint: (a) tensile samplevice to examine the strength and the plasticity ofal welded rails and here D is 1000 mm. A model0 kN bend-fatigue test equipment is employed toe bend-fatigue strength of the welded joint. It ishree-point-bend-fatigue test device to examine thength of the practical rail or welded rails and here DWhen testing the bend, the top of the rail is down-distance between two fulcrums is 1000 mm and thethem is the welded joint to put a load on it. Whileg the bend-fatigue, the top of the rail is upwards,e between two fulcrums is 500 mm and the middle ofwelded joint to put a load on it. Their schemata arethe ratio of load for the bend-fatigue test is 0.2. Allcedures strictly follow the corresponding standard instructure of welded jointcrostructures of the welded joint are investigatedmodel Nephoto-21 optical microscope. A model0/PC X-ray diffraction equipment is employed toe residual stress of the welded joint. The D/max--ray diffractometer system includes focusing andam optics, which can be exchanged by the userinute without realignment. Variable slits are stan-iding exceptional low-angle performance down tocan be a real benefit to many pharmaceutical andapplications. The Cu K acts are the radioactivethe X-ray diffractometer. The accelerative volt-s equipment is at 50 kV, and the current is ate and (b) impact sample.F. Zhang et al. / Materials Science and Engineering A 454455 (2007) 288292 291Fig. 4. Micro ng: (a) pearlite in HAZ of carbon steel rail, (b) austenite and ferrite inHAZ of stainl3. Results3.1. MicroFig. 4 shis shown thHAZ of theite, but carof the highcrack occusteel, becauabout 0.006steel is aboto form Mon the graithe ferritebe avoidedconsideratisumable iswork.3.2. MechaFrom ththat good mships of thjoint and aindicated thwith the incis less thanthan 10 michange witthat there iscarbon steeing treatmecarried outreleased viature and tha low leveljoint can eBend and bend-fatigue strengths of welded joint vs. annealing time athigh carbon steel rail that may occur during cooling afterg. So the annealing treatment is a very useful method toe the mechanical properties of the welded joint, not onlynd strength and the bend-fatigue strength, but also thel mechanical properties. The general mechanical proper-the welded joint are listed in Table 4. It is indicated thatlded joint of the high carbon steel and the stainless steelstructures of welded joint of carbon steel rail and high manganese steel crossiess steel insert and (c) austenite in HAZ of manganese steel crossing.and discussionstructure of welded jointows the optical microstructures of the welded joint. Itat there is only pearlite, but martensite in the weldinghigh carbon steel rail. There is single-phase austen-bide or hot crack on the grain boundary in the HAZmanganese steel crossing. It is well known that hotrs easily in the welded joint of the fully austeniticse of solubility of sulphur in austenite is very low,wt%, and usually the content of sulphur in stainlessut 0.02 wt%. The sulphur combines with manganesenS, which has a low melting point, gets segregatedn boundary and causes the hot crack. However, ashas a high solubility for sulphur, the hot crack can[14]. This is one of the important factors taken intoon when the insert material is designed and its con-successful in suppressing the hot crack in the presentnical property of welded jointe microstructures of the welded joint, it is expectedechanical properties will be obtained. The relation-Fig. 5.900 C.of theweldinimprovthe begeneraties ofthe wee bend and the bend-fatigue strengths of the weldednnealing time at 900 C are shown in Fig. 5. It isat the bend-fatigue and bend strengths will increaserease of the annealing time when the annealing time10 min. However, when the annealing time is moren, the bend and the bend-fatigue strengths will noth the increase of the annealing time. The reason isa very high residual stress in the welded joint of thel rail and the stainless steel insert before the anneal-nt. As is shown in Fig. 6, if the annealing treatment isfor the welded joint, the high residual stress will bea the plastic deformation of the steel in high temper-e residual stress in the welded joint will decrease to. Meanwhile, the annealing treatment of the weldedliminate the martensitic transformation in the HAZFig. 6. Residinsert beforebefore annealafter annealinual stress in welded joint of carbon steel rail and stainless steeland after annealing treatment at 900 C for 10 min. (1) Rail toping treatment, (2) rail top after annealing treatment, (3) rail middleg treatment and (4) rail middle before annealing treatment.292 F. Zhang et al. / Materials Science and Engineering A 454455 (2007) 288292Table 4Mechanical properties of welded joint of high manganese steel crossing and carbon steel railPosition of sample in rail Tensile strength (MPa) Impact toughness (J/cm2)Top 589 [535] A/25 B/88 C/233 D/136 E/246Middle 621 [527] A/22 B/40 C/254 D/188 E/235Bottom 652 [551] A/20 B/54 C/230 D/139 E/253(1) The numbers in square bracket are the tensile strengths of non-annealed welded joint; (2) AE indicated the position of U-shape gap on the samples correspondedto in Fig. 2(b); (3) all of the experimental data of the mechanical properties are the average value of 10 samples tested.rail subjected to the annealing treatment at 900 C for 10 minhas exhibited high tensile strength and enough impact tough-ness. However, the mechanical properties of the welded jointnon-subjected to the annealing treatment are very low.The technology of flash butt welding of the high man-ganese steel crossing and high carbon steel rail described in thispaper has been applied in the railway systems in China, Korea,Venezuela, Indonesia, Iran and India.4. Conclusions(1) A high quality welded joint of the high manganese steelcrossing and the carbon steel rail has been obtained by theflash butt welding technology via the austeniteferrite two-phase stainless steel insert.(2) There is no carbide precipitation on the austenitic grainboundaand thecarbonof the w(3) The opjoint oat 900AcknowledgementsThe work was supported by National Nature Science Founda-tion of China and Nature Science Foundation of Hebei Province.The project nos. are 50671091 and E2006001026, respectively.References[1] J. Mendez, M. Ghoreshy, W.B.F. Mackay, T.J.N. Smith, R.W. Smith, J.Mater. Process. Technol. 153154 (13) (2004) 596602.[2] M. Alfred, H.J. Augustin, USA Patent, US4,169,745 (1977).[3] M. Bartoli, M. Digioia, Riv. Ital. Saldatura 39 (1) (1987) 38.[4] M. Alfred, H. Augustin, USA Patent, US4,724,890 (1988).[5] J. Blumauer, USA Patent, US5,170,932 (1991).[6] F. Pons, A.M.J. Spolidor, D.L.Seillier, USA Patent, US5,304,777A (1994).[7] P. Cerny, Canadian Patent, CA2,343,847 (2002).[8] T. Shimizu, M. Mune, A. Komori, Europe Patent, EP0,761,378 (1996).Barre97).AlfreMead. ZhaShank. Borasumry in the HAZ of the high manganese steel crossing,re is no martensite transformation in the HAZ of thesteel rail, both of which have avoided the brittlenesselded joint effectively.timum annealing treatment technology of the weldedf the carbon steel rail and the stainless steel insert isC for 10 min.[9] L.(19[10] K.[11] B.[12] F.C[13] V.[14] J.C[15] I. Mncua, A. Jose, J. Sanchez, C. Juan, World Patent, WO9,741,305d, R. Gerhard, K. Walter, World Patent, WO9745,228 (1997).e, Weld. J. (USA) 76 (9) (1997) 4752.ng, A.Y. Xu, Chinese Patent, CN2,000,121,442 (2000).ar, Weld. J. 5 (1998) 193201.land, R.N. Younger, Weld. J. 7 (1960) 2259.oto, Trans. Jpn. Weld. Soc. 21 (4) (1990) 1217.Flash butt welding of high manganese steel crossing and carbon steel railIntroductionExperimental proceduresMaterialsWelding procedureMechanical properties of welded jointMicrostructure of welded jointResults and discussionMicrostructure of welded jointMechanical property of welded jointConclusionsAcknowledgementsReferences

Recommended

View more >