Available online at ScienceDirect. Procedia Engineering 111 (2015 )

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1 Aville online t ScienceDirect Procedi Engineering 111 (2015 ) XXIV R-S-P seminr, Theoreticl Foundtion of Civil Engineering (24RSP) (TFoCE 2015) Experimentl determintion of deformtions of the hrd fced smples mde of steel for operting t elevted tempertures Vukić Lzić, Dušn Arsić, Ružic Nikolić, *, Srislv Aleksndrović, Miln Djordjević, Brnislv Hdzim, Jn Bujnk c Fculty of Engineering, University of Krgujevc, Sestre Jnjić 6, Krgujevc 34000, Seri Reserch Centre, University of Žilin, Univerzitn 8215/1, Žilin , Slovk Repulic c Fculty of Civil Engineering, University of Žilin, Univerzitn 8215/1, Žilin , Slovk Repulic Astrct An experimentl procedure for determintion of the lterl nd longitudinl deformtions of the multi-lyer hrd fced smples mde of steel for operting t elevted tempertures is presented in this pper. Two pltes, which were hrd fced in three psses, were used to determine the level of residul stresses. The cored electrodes UTOP 38 nd UTOP 55 were used. Deformtions were mesured in two phses: efore nd fter the hrd fcing. The ojective of deformtions mesurements ws to estlish the correltion etween deformtions, nmely the pplied technology (the input energy/het) nd the level of residul stresses, for different plte thicknesses The Authors. Pulished y Elsevier B.V The Authors. Pulished y Elsevier Ltd. This is n open ccess rticle under the CC BY-NC-ND license ( Peer-review under responsiility of orgnizing committee of the XXIV R-S-P seminr, Theoreticl Foundtion of Civil Peer-review Engineering under (24RSP) responsiility of orgnizing committee of the XXIV R-S-P seminr, Theoreticl Foundtion of Civil Engineering (24RSP) Keywords: Hrd fcing; Filler metls; Deformtions; Residul stresses; Driving energy. 1. Introduction In this pper is pointed to the complex prolems of reprtory hrd fcing of forging dies, which re in exploittion conditions exposed to impct loding nd cyclic heting up to elevted tempertures. Steels imed for mnufcturing of those tools thus hve to sustin high impct lods, while preserving good mechnicl properties t elevted tempertures nd they hve to e resistnt to wer nd therml ftigue. From ll the mentioned resons, for * Corresponding uthor. Tel.: E-mil ddress: ruzicrnikolic@yhoo.com The Authors. Pulished y Elsevier Ltd. This is n open ccess rticle under the CC BY-NC-ND license ( Peer-review under responsiility of orgnizing committee of the XXIV R-S-P seminr, Theoreticl Foundtion of Civil Engineering (24RSP) doi: /j.proeng

2 496 Vukić Lzić et l. / Procedi Engineering 111 ( 2015 ) those tools re used lloyed steels, which hve reltively poor weldility wht impedes regenertion of the dmged tools y the hrd fcing procedures. This is why ny reprtion y hrd fcing is prcticlly unique jo, since it sks for the technology to e dpted to ech individul working piece. However, the generl procedure could e estlished, which must e oeyed if one expects to successfully repir the forging dies nd similr tools. Prior to eing le to select the optiml reprtion technology, one must conduct numerous model investigtions, wht is prtilly presented in this pper. In ddition, esides the selected technology of hrd fcing, results of experimentl mesurements of deformtions, which regulrly pper ecuse of the het input during the welding, re presented in this pper. Nomenclture BM se metl FM filler metl HF hrd fcing I welding current T p preheting temperture U welding voltge width of the hrd fced lyer d e electrode dimeter h height of the hrd fced lyer q l driving energy s plte thickness v z welding/hrd fcing speed 2. Bse metl (BM) properties Steel 55CrMo 8 (SRPS Č 5742, DIN - 56NiCrMoV7) ws pplied s the se metl out of which the thin nd thick pltes were mde, with thickness of 7.4 mm nd 29 mm, respectively. Steels lloyed with Cr, V nd Mo, with incresed content of cron ( % C) provide the good hrdenility, needed for lrger cross-sections of tools, s well s higher hrdness t elevted tempertures [1-5]. The chemicl composition, mechnicl properties nd microstructure of those steels re presented in Tles 1 nd 2, respectively [6]. Since the forging shops minly use dies in the het tempered condition Q+T (quenching nd high tempering), ll the smples-models were sujected to tht het tretment, in order to simulte the exploittion conditions s close s possile. Hrdness ws mesured on selected smples fter the het tretment, nd it rnged from 40 to 42 HRC. Tle 1. Chemicl composition of 58CrMo 8 steel. C Si Mn P S Cr Ni Mo V Tle 2. Mechnicl properties nd microstructure of 58CrMo 8 steel. Soft nneling Tempering B. M. Microstructure t, C HV mx R m, MP t, C HRC R m, MP M + B (interphse) Smples of vrious thickness (s = mm) were hrd fced for experimentl purposes to steels prone to selfhrdening (C > 0.35 %); thus it ws necessry to pply preheting. The preheting temperture ws determined ccording to Seferin's formul [7] nd it ws within rnge from T p = 286 C for s = 7.4 mm up to T p = 315 C for s = 40 mm. The dopted preheting temperture ws T p 300 C [1, 5-7].

3 Vukić Lzić et l. / Procedi Engineering 111 ( 2015 ) Selection of the hrd fcing method, technology nd the filler metl (FM) Hrd fcing of the selected smples ws done y ppliction of the cored electrodes. Technologicl prmeters of hrd fcing were determined ccording to recommendtions from [1, 5, 6-9], while the hrd fcing ws executed with two nd three psses. This is done to reduce the mixing-dilution, i.e., to otin the declred properties, provided y the electrodes supplier [12]. The deposition speed ws mesured in ech pss, while the preheting temperture, nmely the interpss temperture, ws checked prior to deposition of ech new pss, i.e., lyer. The mesuring device ws Tstotherm D1200 (with thermocouple NiCr-NiAl nd mesuring rnge from 50 ºC to +1200ºC). The filer metls were highly lloyed sic electrodes UTOP 38 (E3-UM-40T 3.25 mm - DIN 8555) nd UTOP 55 (E6-UM-60T 5.00 mm - DIN 8555). They re used for hrd fcing of tools like: steel molds, dies nd thorns for pressing, etc. Hrd fced lyers re tough nd resistnt to wer nd impct [8-10]. Hrdness of the hrd fced lyers, ccording to conducted tests, ws stle until 570ºC (tempering temperture) [1, 7]; ccording to electrodes' supplier hrdness is stle up to 600ºC [12-1]. Prior to ppliction, electrodes were dried for 2 h t ºC. Drying of electrodes cused reduction of the diffused hydrogen nd prevented hydrogen induced crcks. In Tles 3 nd 4 re presented prmeters of hrd fcing (the hrd fcing current is for out 10% smller thn for welding), s well s the properties of the filler metls, respectively [1, 12-1]. Tle 3. Prmeters of hrd fcing y the MAG method. No. Electrode mrk Core dimeter Hrd fcing Voltge Hrd fcing speed Driving energy SŽ Fiprom DIN 8555 d e, mm current I, A U, V v z, mm/s q l, J/mm 1. UTOP 38 E3-UM-40T UTOP 55 E6-UM-60T Tle 4. Filler metls properties [12]. No. Electrode mrk Chemicl composition % Hrd fced lyer Current type hrdness, HRC SŽ Fiprom DIN 8555 C Cr Mo V W 1. UTOP 38 E3-UM-40T = (+) UTOP 55 E6-UM-60T = (+) Order of depositing the hrd fced lyers is shown in Figure 1. Prior to ech new pss, the slug ws removed y the steel rush. Other lyers were deposited ccording to this scheme (the second Figure 1), the third Figure 1c), etc.). The lyer hrd fced with electrode of dimeter 3.25 mm hd dimensions: width ws mm nd height h 1.5 mm, while the lyer deposited with electrode of dimeter 5.00 mm hd dimensions: width ws mm nd height h 2.1 mm. 4. Experimentl mesurement of deformtions on the hrd fced smples Smples tken from the thin nd the thick pltes were prepred y grinding for experimentl mesurement of deformtions (Fig. 2). The pltes' dimensions were mm - 4 pieces nd mm 3 pieces. Deformtions were mesured in two phses: efore the hrd fcing fter the pltes' preprtion y grinding nd immeditely fter the hrd fcing. The ojective of those mesurements ws estlishing the correltion etween deformtions, nmely the pplied technology (the input energy-het), nd the mgnitude of the residul stresses, for different thicknesses. After the pltes were prepred y grinding, the rster ws pplied to their surfce the stright lines in three longitudinl directions (I-I, II-II nd III-III) nd in three lterl directions (IV-IV, V-V nd VI-VI), with totl of 111 mesurement points in the x-y plne (Fig. 2). The contct-mesuring device OPTON UMC 850 ws used for deformtions mesurement.

4 498 Vukić Lzić et l. / Procedi Engineering 111 ( 2015 ) Fig. 1. Order of deposition of the hrd fced lyers: () lyer 1; () lyer 2; (c) lyer 3; (d) metllogrphic slit scheme. y III II I O Zero point IV IV V V VI VI III II I x Step long the x xis - 20 mm, step long the y xis - 10 mm Fig. 2. Schemtics of the pltes' nd their clirtion. 5. Results The longitudinl nd lterl deformtions were mesured within the experimentl investigtions. Otined results re presented in the form of digrms for the corresponding mesurements directions (Fig. 2) nd pltes. The mesured longitudinl nd lterl deformtions for the thick plte (s = 29 mm), efore nd fter the hrd fcing, respectively, re presented in Figures 3 nd 4, while in Figures 5 nd 6 re presented longitudinl nd lterl deformtions, respectively, for the thin plte (s = 7.4 mm). In Figures 7 nd 8 re presented results of the deformtions' mesurements for the thin nd the thick plte, respectively, in the form of the 3D digrms with the deformtions distriution long the plte's width nd length nd the corresponding fields.

5 Vukić Lzić et l. / Procedi Engineering 111 ( 2015 ) Fig. 3. Lterl deformtions of the thick plte #2 (s = 29 mm); () efore; () fter the hrd fcing Longitudinl deformtions fter hrd fcing Plte No. 2 - s= 29 mm Direction II-II Direction I-I Direction III-III Fig. 4. Longitudinl deformtions of the thick plte #2 (s = 29 mm); () efore; () fter the hrd fcing Fig. 5. Lterl deformtions of the thin plte #6 (s = 7.4 mm); () efore; () fter the hrd fcing.

6 500 Vukić Lzić et l. / Procedi Engineering 111 ( 2015 ) Longitudinl deformtions efore hrd fcing Plte No. 6 - s= 7.4 mm Direction II-II Direction I-I Direction III-III Longitudinl deformtions fter hrd fcing Plte No. 6 - s= 7.4 mm Direction II-II Direction I-I Direction III-III Fig. 6. Longitudinl deformtions of the thin plte #6 s = 7.4 mm); () efore; () fter the hrd fcing. Fig. 7. 3D deformtions of the thick plte #2 (s = 29 mm); () efore; () fter the hrd fcing. Deformtions fter hrd fcing Plte No. 7 - s= 7.4 mm B.M. 58CrMo 8 - F.M. UTOP 38 de= 3.25 mm Three lyers - three psses Fig. 8. 3D deformtions of the thin plte #6 (s = 7.4 mm); efore nd - fter the hrd fcing.

7 Vukić Lzić et l. / Procedi Engineering 111 ( 2015 ) Conclusion The technology of hrd fcing of the thin nd the thick plte is presented in detils in this pper. By mesurements of deformtions, it ws estlished tht they re the most prominent in hrd fcing of the thin pltes, when the drstic increse of deformtions pper t ll the points of the hrd fced lyer in oth the lterl (Fig. 5) nd longitudinl direction (Fig. 6). For thick pltes, however, the increse of deformtions in the lterl directions is negligile (Fig. 3), while the increse in the longitudinl direction (Fig. 4) is more prominent. This is confirmed y the corresponding 3D digrms (Figs. 7 nd 8), wht verifies the conclusion tht the thin pltes (s = 7.4 mm) deform more thn the thick pltes (s = 29 mm). Acknowledgements This reserch ws prtilly finncilly supported y Europen regionl development fund nd Slovk stte udget y the project "Reserch Centre of the University of Žilin" - ITMS nd y the Ministry of Eduction, Science nd Technologicl Development of Repulic of Seri through grnts: ON174004, TR32036, TR35024 nd TR The uthors re very grteful for this funding. References [1] V. Lzić, M. Jovnović, D. Admović, N. Rtković, Selection of the optimum technology of the forging dies reprtion from the spect of triologicl chrcteristics, Triologi - teori i prktik, 28/2 (2005) [2] E.I. Beljski, Persistence of forging dies, "Science nd technics" Pulishing, Minsk, (in Belrussin) [3] R. Psier, Welding of chromium-molydenum steels for operting t elevted tempertures, WNT, Wrszw, [4] V. Lzić, M. Jovnović, J. Ristović, B. Nedeljković, D. Josifović, D. Admović, Influence of het tretment fter hrd fcing on working chrcteristics of the hrd fced forging dies, Welding nd welded structures, 46/1-2 (2001) (In Serin) [5] V. Lzić, A. Sedmk, S. Aleksndrović, D. Milosvljević, R. Čukić, V. Grulov, Reprtion of dmged mllet for hmmer forging y hrd fcing nd weld cldding, Technicl Gzette 16/4 (2009) [6] D. Arsić, V. Lzić, R. Nikolić, A. Sedmk, S. Aleksndrović, M. Djordjević, R. Bkić, I. Smrdžić, Selection of the optiml hrd fcing (HF) technology of dmged forging dies sed on cooling time t8/5, Metllurgy, 54 (2015) (In press). [7] M. Mutvdžić, V. Lzić, D. Milosvljević, S. Aleksndrović, R. Nikolić, R. Čukić, G. Bogdnović: Determintion of the optiml tempering temperture in hrd fcing of the forging dies, Mterils Engineering, 19 (2012) [8] V. Lzić, M. Mutvdžić, D. Milosvljević, S. Aleksndrović, B. Nedeljković, P. Mrinković, R. Čukić, Selection of the most pproprite technology of reprtory hrd fcing of working prts on universl construction mchinery, Triology in Industry, 33/1 (2011) [9] S. Mrković, LJ. Milović, A. Mrinković, T. Lzović, Triologicl spect of selecting filler metl for repir surfcing of gers y hrd fcing Structurl Integrity nd Life, 11 (2011) [10] V. Lzić, A. Sedmk, B. Krstić, R. Nikolić, S. Aleksndrović, R. Čukić, Determintion of the cooling rte nd its influence on the hrd-fced forming dies properties, Mterils Engineering, 16/3 (2009) [11] Stndrds nd ctlogues of the se metl: 1. Steel mill "Rvne", Sloveni, 2. Thyssen Mrthon Edelsthl: Verkufsgesellschft M.B.H., Vosendorf, Germny. 3. Atls zur Wärmeehndlung der stähle, Verlg sthleisen M.B.H Düsseldorf, Germny. [12] Ctlogues of the filler metls: 1. Steel mill "Jesenice-Fiprom", Sloveni. 2. Bohler-Kpfenerg, Messer Griesheim-Frkfurt m Min, Germny. 3. Es-Göteorg, Sweden. 4. Lincoln Electric-USA.