IGIN

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Puol~nw quaneny as me organ or me rounary tommisston or me rolrsn Hmaemy of SGisn~es

Application of welding technology TIG to cast iron repair

J. Sza,j!jaar " P. \VrbbcI" T. Wriibcl" * "ilcsian University ol*'Tcchnology, Inslitute o f Engineering Materials and Biorn;ltcrials,

Foiindry Dcpnrtrncnt, Tawarowa 7,44- 100 G I iwicc, PL *Corresponding author. E-mail address: tomasz.wrobcl@polsl.pl

Rcccivcd 12.02.2008; acccpted in rcvised form 13.02.2008

Abstract

Rcpnir nT cnst imn clcrncnts rcaEi7c in ordcr to cut out a sltpcrficial casting dcfcc~s, Dcrccis clccrcasc ;z usahiliny nt ca~rings tor consin~ciional application m d incrcasc a manufacturing costs. Thc pnpcr prcsclrls rcscarch rcsufts or itsc o r '1'IG - Tun~stcn Incn Gas also kncwn RS GTA - Gas Tunpstcn Arc surfacin: hy wclding on colt1 and half-hot to rcpnls chrninil~m cnsr iron EN-GJN-XCrlS with cliro~niurn contcnt nhout 3 5% and nodular ({vi~h Fcrritic-pcarli~ic matrix) cast iron EN-GJS-500-7. Thc rcsttl~ or invcsiigations show possibility of cns~ings rcpais hy put on derccts a good quality padding wclds, which havc compamhlc nr hcricr propcrtlcs than hnsc ~naicrial.

Kcy words: Surfncc Trcalmair. Casting Dcfccts. 'TIG. Chromi~un Cast Iron. Nodular Cast Iron

1. Introduction Oitcn. for this aim i s uscd wcld~ng tccIlnology fur cx:implc 'r1G - Tungncn Incrt Gas also known as GTA - Gi~s ?iin~sicn Arc F7t1 I].

Wcar rcsisiancc i s w r y ilnporlant fnr clclncnts of machincs TIG nr GTA surfacing hy wclrli~ig i s :in arc wcldlng pmccss and dcviccs such as: cIig~cr tccih, jaw nT cn~sllcr. which arc

that uscs a nonconsiirnahlc ~iulgsicn clccirodc lo pro(1i1~1: I~IC subject in ridying. grintlirlg ant! c~~ss io l i . Rilsic lnntcrii~ls which

padding \rrrld (fiy. I ) . has high wcar rcsislancc is chromium cnst iron. I ligh wcar rcsis~itncc in I his ma~criiils rcsuIr froin dispcrsio~t of Cr7C3 carhides and iron1 finc-prninctl, hr~nngc~lcouq anlcturc of this Shield~ng gas

alloy [ 14-13, Gray cast imn is an vcry vcrsatilc maicrial iuld rcla~ivcly

incxpcnsivc, usctl in thotlrirnrls of industrial produc~s. Gray caa irnn with flitkc anrl slnclt~lar grapliiic hclnng to thc most popular ;rlloys in ihis proup, l lowcvcr, !ncchanical prapcrtics or ductilc cast irnn arc hatcr than pray cast iron w i ~ h flakc ~raphitc 1 I. 5. 6 ) .

'rhc \r,cldnhility nf cihst imn is dirficult in particulary nn cold - wi~trorl~ prchcating. Fnr lijsion wclding. prchcating of thc caning is nhscilulcly csscntial. R ~ i l s~trfitcing by wclding on cold to rcpnir cast iron is pmsihlc. Rcpnir of cast iron clcmcnts rcnlizcd in ordcr lo cia nil1 a casting dcrccts. which dccrcnsc a ~isabili iy of cast 10

cor~stn~ctinnnl application md incscnsc a manufacturing costs. Fig. I. Schcmc of TlG surfacin~ hy \c,cldin_c kcchi~olnyy

A R C H I V E S or F O U N D R Y E N G I N E E R I N G V o l u m o 8, SpociaE l s s u o 112008, 3 1 7 - 3 2 0 3f7

Tbc welding arc is crcatcd bctwecn a rungstcn clcctrodc and the weld pool. Thc wcld arca is protcctcd from atmospheric contamination by a shicfding gm - usually an incrt gas such as argon or seldom helium. FiIlcr in form of rod. wire, shapcd win: or powder is uscd. A constant-currcnt welding powcr supply produccs cnergy which is conducted across thc arc through a column of highly ionizcd gas and mctal vapors known as a plasma [ l l+ lS] .

Morcovcr, application of wclding technology in particular TIG to surfacc heat trcatmcnl guarantcc mechanical propertics i.c. hardncss and wcar rcsistancc improvcmcnt in gray cast iron [7. 8. 1 1 I.

2. Range of studies

Rcpair OF chromium cast iron EN-GJN-XCrlS and nodular cast iron EN-GJS-503-7 clcrncnts was realized with usc of wcIdcr dcvicc CastoTlC 2002 ACIDC with cursent intensity 100A for surfacing by wcidnig on cold and half-hot (prchcating tcmpcraturc 300°C). Fillcr in form of rod to surfacing by wclding of chromium cnst iron has thc samc chcrnicaf cornpsition as bnsc material. Whcrcas fillcr to sz~rfacing by wclding of nodular cast iron was chromium cnst stccl G90CrSi12- 1 with slmmium contcnt about 13%. Ratc nf flow of shielding gas - argon was

Hardness cxarninations wcrc madc on ultrasound MIC;! hardncss tcstcr with load 49N. Microhardness cxaminntions wcrc madc on microhardncss tcstcr D32 - VEB Carl Zciss Jcna with load 0,3824N. Wcar rcsistancc invcnigations wcrc mcasurcd an thc basis of ASTM G 65 - 00 standard (fig.2). Valuc of wcar rcsistancc is dcscribcd by volume loss [ IG]:

wherc: R - volumc loss, mm3, Am - mass loss, g p - density, dcrn.'.

3. Results and analysis

On figurc 3 is prcscnicd Fi~sion nrca nrtcr rcpair surfacing by wclding OF chromiu~n cast iron EN-GIN-XCrl5. Invcsiignrcd chromium cast iron has sfructurc of fcrrirc and carbidc cutcctic (fcrritc + M7C3) (fig.3). Thc same stnlcturc but finc-graincd has put padding wcld in placcs of casting dcrcc~s (fig.>).

Sllmin. Nonconsumnblc clcctrode (W + 29Th03 @ 3.2mm was used.

Mctalloprnlic cxarninations of thc matcrial structurc wcrc made on Nikon light microscope with magnihcation from 50x to GOOx. SurTaccs o f snrnplcs which wcrc prepared for microstructure anaIysis were etched with use or FcCI3 for chromium cast iron and casl stccl padding wcld and Nital for nodular cast imn.

Hopper with sand

Fig. 3. Strucrure of fusion area in chromium cast iron - fcrritc and carbidc cutcctic (fcrritc + M7C3) - asca 2.

no re finc-gnincd in padding wcld - area I, magnilication: 20Qx. ctching: FCC&

Rubber lined wheel

Fig. 2. Schematic diagram of test apparalus ro wcar rcsistancc investigation [I61

Investigated nodular cast iron has structurc of nodi~lm graphite in ferritic-pearlitic matrix (fig.4). Whilc rcpair padding wcld has fine-grained structurc of cast stccl G9OCrSi 12-1 (fig.5). On figure 6 is presented fusion area artcr repair surfacing by weIding of nodular cast iron EN-GJS-500-7.

Whilc. padding weld aftcr surfacing by welding with prchcating has larpr qualiiy (withou~ cri~cks in 1.IAZ - hcat affcclcd zonc and lack of wcld pcnctration) th,m padding welds at7er surfacing by welding on cold (fig.7 and 8). It rcsu!t From large increase of HAZ hardness in sample after surfacing hy welding on cold (fig.9 and 10). Wheras increase or hardncss in HAZ rcsult from creating of whitc casi iron nruculre in fusion area after fast cooling.

A R C H I V E S of FOUNDRY ENGtNEERlNG Vo lume 8 , Spec ia l I s s u e 1 /200&, 317-320

Fir. 7. Mncrostructure of paddinfi wcld nltcr surfacinfi hy wclding

Fig. 4. Srrunurc of nodular cast iron EN-GJS-500-7 - nodular graphite in fcrrit ic-pcarli~ic malrix,

magnification: 200x, ctching: Nital

Fig. 5. Finc-grained dendritic structure of padding wclti on nodular casl iron EN-GJS-500-7,

magnification: 600~. etching: Nital

Fig. 6. Stmcture of fusion area in nodular cast iron EN-GJS-500-7 artcr surfacing by wclding

on cold - finc-graincd stnlcturc in padding weld of cast sfccl G90CrSi 12- 1 ant! anrcturc of whitc cast iron

i n rusion line, magnification: 400x, ctching: Niral

- TIG of chromium cast iron EN-GJN-XC~~S:

a - on cold (without prchearing), b - on hot-cold (prchcaling lcmpcraturc 300°C)

Fig. 8. Macrostructurc of padding wcld dtcr surfacing by wclding TIG of nodular cast iron EN-GSS-50-7:

a - on cold ('without prchcating), h - on hot-cold (preheating tcmpcraturc 300°C)

- on cdd

- - - .on hall.l>at

Fig. 9. Distribulion of hardncss on cross-scc~ion of chromium cast iron EN-GJN-XCrlS aftcr wlrracing hy wclding TlG

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Fig. In. Dislrihti!ion nr hardncss on cross-section of nodular cast irnrl EN-GJS-500-7 nf~cr surracing by welding TIG

Mnrcovcr, hardncss and wear rcsistancc (fig. 1 1 ) of padding wcld in hoth cnscs is larger than in hasc inntcrinl.

Fig. I I. V a t ~ ~ c of wcar resistance of chro~iiium and nod11 tar cast irnn aRcr surfacing hy wcltling 'l'lG

4. Conclusion

Rnsctl on mnductcd s~otlics hllnrving ctmclusions hnvc been rorznulatd: I . Possibility haw hccn shown of chromium cast iron

EN-GJN-XCr 1 S nnd ~intlulnr c;in iron EN-GJS-500-7 castings repair by put on dcrccts a good qi~aIity padding wcltls will1 usc 'TIC; tcchnotngy.

2. Padding wcld on chromium caa imn nnrt ntxblnr cast irnn aitcr surfacing by wclding rvirh prclicaling (T = SM°C) has bcttcr quality than padding tttclds ohcr airfacing hy i c ld ing on coEd.

[ 1 ] \V. Snkwn: Cast iron. Silcsinn Pr~hlishcrs, Kntowicc, 1974 ( i l l Polish).

[21 M. Przybyl. A. Studnicki. J. KiInrski: Distrihutic~n i )S srcrcological pararnacrs nf chro~niurn cast iron on scc~ioa castings, Archivcs of Foundry, No. 10, vaf. 3, 2003 ( i r r Polish).

[31 M. I'rzyhyl, A. Studaicki: Infli~cncc o f beat truntmczlt on sclcct propcnics of ivcar rcsistancc chrotnium cast s~ccl , Archivcs of Fot~ndry, No. 22. vol. 6.2nM (in I'olirh),

4 A Studnicki: Rccord a r primary ant! sccnntliiry crystalli7ation proccss of wcnr rcsistnncc chnlrniurn citst irnn. Archivcs of Foundry. No. 22, vol. 6, 201)O (in 1411isl1).

[ 5 ] C. Podmucki: Cast iron, %G STOP t'uhlislicrs. Krakilw. I90 t (in Polish).

[6 ] M. Stawnm. J. Sznjnnr: Qiial ific:~tinii mcclianic:il pmpcrtics of ducrilc cast iron with A'1'1) mc~hod, Archivcs or Foundry, No. 15. vol. 5. 2005 (it1 I'oIisl~).

[ T I A. W. Orto\vicz. A. Trytck: Solidilicntian stn~clurc GTh\.\"- frcatcd iron castin~s, Archivcs of Foi~ndry, No. 4, vol, 2. 2002,

[8] A. W. Orlo\r.icz. A. Tn rck: Structure of surhcc rusinn Ynnc on ducrilc iron c;~stinps. Archivcs or hiindry, No. 10. vol. 3. 2003 (in Polish).

[9 ] J. Szajnar. P. Wrtihcl, T. \VbbcI: TIC surfacing - ~ncthod of rcpnir chmmium cast iron with castinps dcfccls. Archivcs of Foundry, No. 22, vol. 6.2006 (in Polisfr).

[ 101 J. Lnssociilski: Duc~ilc cast iron nnil 11icir wct~lnhility. Wclding Rcvicw, N n 12, 1379 (in Polish).

[ O I] 3 . Sznjnnr. M. Slawar~. P. Wrilbcl. T. Wrbhcl: I'ropcnics shaping and rcpair of sclcc~cd typcs of ciist imn. Archivcs or Foundry Engineering, No. 2. \wl. 7. ?(M)7.

[ 121 E. Laugsccidcr, G. Lmgcr: t'las~na-arc powder szlrfncing - cornparsion o l standard nnrl high-prnductivi~y proccsscs. SchrvcisscnRcSchncidcn. Nn, 2, IOOX.

[ I31 A. Klimpcl: Surfacing hy wclding and ztvrmaI spraying - ~cchnology WNT. Wnrssnwn, 20011 (in I'olish).

[I41 J. Pilarcxyk. J. I?larczyk: Wclding nf ~nctals, Silcsian Puhlishcru. Katowicc, ll396 (in Pol is)\).

[ 151 \V. Lucas: Arc surfacing and cladding proccsscs, Wcldiiiy 6 Mctal Ltbricaion. No. 2. 1994.

[ 161 Standard AS'TM G 65-00,

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