NASA Technical Reports Server (NTRS) 20050060704: Mechanical Behavior of Gamma-Met PX under Uniaxial Loading at Elevated Temperatures and High Strain Rates

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by  NASA Technical Reports Server (NTRS)

Mechanical Behavior of Gamma-Met PX under-Uniaxial
Loading at Elevated Temperatures and High:Strain Rates

‘Mostafa Sharly aid Vikas Pralssh,
Depart of Mechattang Aerospace Engineering
Case Wedtgm Roser¥e Universi
Geseland, OF dei o-7222

~ Susan Drager
$A Glom Research Center
ABSTRACT

Garr tii sluminies ane recived consiéernble stention over tho last cade, These
alloys ace Knowa to have low density, good high temperature strength retention and god
oxidtion and cotton resistance, However, poor duetiliy and low Gastue magne have
been the key limiting factors in the full utiization of these alloys, Mote:syecutty. 9 new
generation of gamma nium alumni moye, commonly refered 0 Snr ks
ten develope iy GIES, Garay. Theale have been ceed hae eri enh
aud berer oxidation resistance a elevated temperstures when comparedyith conventional

amma fitaniym aluminas,

The present paper diseuses results oF a study to undead he wis mehwniaal behavior

bos compression and tension of Gamm-Me: PX at sevated topsites and high stain aes:
The comprensin and tense teu re conde uring ae pt-sopknson bar apparstos
ce west eapertiesssnging om room empettue 10 900°C and sain rfen of up io 3500s!
Under aniaiak eames, inthe fees nge fom mom ko 600%; the ow ves fs
cbserod to be nec independent of tet epi, However, at temperomres ger daa
400°C themel saerng is observed “tall ron with te rae of them softening
increasing dramatically benveen SOE sng SOHC, The rom seuporta fase ests showe
negligible steain-rate dependence Bf Bh. jield stress and law sts. With an imerease fn text
teaportoe fom ou fo 9OPE% ty htt stows atop in oh ld andy ses al
levels of plastic wovin, Heiever, ite cased flow srs is ill highor when compared to
riche! based supersallssier gamma titanium slimes wer similar tt condoms
Also, no snomalyn Jide sfroa is absorved up wm WIN*C,

BY WORKS
Gig Ms Pdrumieeumpreasion oss dynamic emi et steve temperature
INTRODUCTION

Gacs tisaniom auninides (-TiAL) ate targeted es # material substitute for nickel und iron
‘sed superalloys (LeHfol, Clemens aud Kester, 1999) for citial prepulsim components in
the 600°C 0 900°C femperseure range. Compares with stanium alloys they pngsent several
sdvantages such as higher lastisiey modulus, lower density, beter mechunul behiaor wit
temporaame and higher oxidation resitance by mation of 3 surfie passive aku ayer.
Blwovcr, these properties come ol the expense of teusile ductility, whic eypically im the range
of Fla 3% As a result cese intsmastalics show poor crack-propegaiion wésitance, and in
conlemplaing the use of TiAl in srfils the threw of high-yelociey spell pasticleimpacrs is
‘of considerable concem (Wright 1995: Austin, Kelly,and McAllister, 1997), The abscuce of
plasticity at chewical fbricwiom lempernares is als’ source, of ifeutty in particular in
rolling y-TiA i thin shaet of fol :

Goauma based titanium aluminides have an aljpinum level of 45-52 atomic %. Within this
rogiine, there ure twa phusts of interest: 7-FiAL ordened phce with face conter tetragona! (Zt)
to crystal structure with siterating (002) planés oF Ti and Al atoms (¥oung-Won Kim, 198);
DDimidule et of, 1991; Kirn and Digidik"1O5}: Yamagushi, 199%; Recina, 200; Tai and
‘tingle, 2002), and oxtered ax-TifA pe withthe DO. hecaganal close packed hcp crystal
sseacrure (Djanarthany, Vialé agd Bex, 2001; Mill, Gray and Barure, 2000) Ta an atlerap >
itaprove she mechnuics! propeiis:of gamma titanium sluminides, Pluses AG of Anstia has
developed a now generation’ bf guraia titanium alloys called Gamma Met FX. Gamma Mct PX

is wrilble in both ie dl oes, This product is umgus. boca iis suitable for bath
ropulsion ad ston componenss. Morenver, i has beter ling characteris and
improved yoselfing epeghnicl properion. TE dose not aed the cosy ibication processes
‘ypieolly’ well fag ihe intermetallic components (thin shoct prosessug cost is 10% of other
‘gota glum 21Sys), Shaping and forming can be carved out at relatively low lemperatunes

1a prodig®pags which aro more upvform than those obtained with other methods. Ia surumary
the sain advantages of the y-Met alloys are (a) 7+Met alloy is 15% lighter than titanium alloys

and more than 5

M4 Lighter than superalloys, (b) it withstands tempersmures chat are
approximately 300°C higher than those for titsaiom alloys. (@) ats specific stifiness is
sporosimasly tice at of anion loys and supe Calon rus somal wth
rpc de) esi igh otc emotion de ish species, nd)
friowon con aceite with er ej ao pony he ea se dewiv loys ad
sspentoys (Vesa 200),

A satis ana of ech fc heen cnc in be ant on menting gma
amin ahmed 0 chance it ecanel popes 6 ugsn gf ogee
tu ecical composton at vaow tt ompertus ands als, Fora. ath and
tal (1981) staid he tof ali const can ropes dg loo ede
transition (BDT) behavior. Bartels etal. (1095) have studied i

‘ilntog Walston ewes and
cemperatues on th flow babavior of TLABAL2Cr wi eguised mictGstmctse, Liv otal
(41995) sued the quastatatic tonsil properties of TATALZCr-2ND in toe ltfereat
smicrotctures with diffrent annealing condi Prom these stains tix non anderen that
he filly Jomellar microsteucture shows o slight drop i’ sipengtip to lest lemperarures of 800°C,
sad thon a substandal drop above HOU°C, However, this bile to ductile trzstion tomporstu
(BOAT) conld vot be infeed om factws’eiomphology. For duplex microsmeturcs, &
moderate deop in stength wes observed up 4 30S followed by a sharp daop w1 temperauates
higher thaa 600°C. The BDTT wos fonda the around 70°C, with a dueliy of 117.6% at
100°C, Kumpfert tal, (1995) srt ic ffoet of stain uate on the fracrmce morphology using
S.pinchend semen Tey if le Race meralogy was sentve he mer
microstarciate, test temperate nd iheaplied stvin eae, Das and Clemens (1999) studied the
cffece of strain sate and temipeentnrc-on T-47AL2Cr-0.28i with equiaxed az lamellar colonics.
“Ty found the vic sod im dkbzease slowiy with increasing test temperatures up to GPC, and
then fal sharply 285408°C. “The stain to flue was alsa observed to inerease sharply hetwooa
500°C und §00°C; syeieiing that BDTT to be below 600°C. Tnexeusng the train rate froma 0%
woe

+ Fesulted'iuad increase in yield stress and a corresponding decrease in the sain 10
fie: Wade ch 1, (19999) studied the cffeet of suain-rate and temperature on the tensile
behavio# gf Ti-A7AL2Mn-2ND in nesny lamellar microstructures, They alse observed a

increase in Yield sess wilh a comesponling decrease in strain 10 Tilure ws Ube sein rate eas
Ineroased trom 19 ta 10s
Tn the past Tile work tas been done inthe aes of igh-sinare deformation of TIAL a
clevated temperatures. Fin ell. (1995) sue he dynamic aswell asthe quasistatic properties
of TLA6 SAL-2Cr-3N00.2W wid fine duplex mirostucute, In their study they showed that at
sunin ic of 2000 ths materia shone yield anomaly at 600°C, Maloy and Grey I (1996)
sewed the high stain rte properies oF doplex microntucturn of THABAERCG-2ND in
‘compression, Their study showed thal Ti-48-2-2 hos a yield stress anomaly. appriimately
00°C, However, inthe work of Gade etal, (1997) on duplex mierosruenss SFTIE.SAI-
2-7Nb-2.6Ma, uo yild-amess anomaly was observed, ‘The masa shoved bigfeves dF sain
hardening at all Yevels of plosicsimin and af all Set temperauiey enipeyed in dhe tet
‘Moreover, thermal softeniag was observed as the cest temperature Was dirreaséd/gbove the room
tempera, In fst performed between TOC and 808C! and
2500 seeking and facrare was observed at masrescopie plastic sang of 0.32. However, al
teroperaiures below 700°C ao micro- andlor mac.” cracking Were observed. Vaidya et al.
(1999) stun the properties of T-25A1-1ONb 3V- IMO sae ates of 10° and 3000s au at
seuigeraues froin 196°C to 00°C, Ata sep eof 16 4 and lempermures of 104, the

2 train Fots af approximataly

flow sree war verved oily neeas, wih Snan nis thenColowed by stain softening
[At strain rate of 3000 s', the flow stress Bing, 9Bsétied to inerease with stain and was higher
thn that obsored at 10" 5°, Sualiistsolng wes obsored to be independent of test
rexmporatures except abave 940°C; sieht ofening was observed, Yield anomaly inflow stress
was observed to be around 600°C at ieaig mtes of 10? 3", However, a0 yield anomaly was.
observed ar strain rates of 3008's," Wang et al. (19990) studied the high-strain-rato tensile
properties of both duplex i fut lamellar snicrostustives of TE-ATALI SCt-SMo-2. AND at
rowin temperature. Coan iithecbservations of Maloy and Gray (1996), they showed that

che steugth of dope microstuenines of TiW-2-2 decreases with increasing ste ras.
However, for filly Jimdlar microstructures, they showed shat the strength of the matstial
nore ih incebig rain rates. Wang st al, (19586) ao conducted hiphatrainate
espero ey amelie oicnea of F-ATAL2MR-2Nb, They alto cbtewed
Increasing! amptevial strengths with nereasing stain rates. More roceutly. Bartcls ct al. 2002)
investiga The mechanical properties of 7-TIAI bel aioy wh (lly lamellar trie
under bot quasi-static and dynamic loading conditions. The txts were conducted rm
tompertucs and strain cates ranging Hom 5.010 %s" 10 4020's", The remus of the
compression teats shawed slight atrain-rate sensitivity ofthe post yield stress

“The present paper preseuts results ofa study to underssad the uniaxial behavior of Garaua-Met
PX alloy dovelopod by GKSS. Germ. Uniexial compression and eensilc tests wie couduciee
2 terperatres ranging from roe up #9 900°C and train rmes ranging ebm quasate oo
3600 s". Ty otder to conduce Bese experiments 6 modifed Spit Hopkins Pitge Bar
(SHPB) and a ireet Split Hopkinson Tension Bar (SHTB) were employed,’ The dlevared
temperature dynamic compreasion sats Were conducted using an infard apat heating sous. In
onder eum he elevated Leaperature unianillesile ets dt dl. eating nyse
was employed.

EXPERIMENTAL WORK
MATERIAL

Cans Mt FX at shen congo T}4SALNIND, B,C). The mt! wd he
present study was supplicd by Plansse AG in thé'Biem of 12.5 mm reds, ‘The material was VAR
vast und thin hot extruded above the alpha trait Lemperature. ‘The extrusion ratio was 100:1

fad the boes are inthe as-extruded condfticis-fitrostrucmedl investigation, Figure J, shows that
‘he material consists of noncly lami lgrosticmne, ‘The nesly lamellae mlerestenctre has
been shown to provide thee alloys th High senggh and acceptable levels of ductty (Kin,
1989). fe
Figure 1: Microstructure of the as received Gamma MX PX

Tr ender us mul the quatisace compreign tet, cylin fe apecmens, mm i
inate an 8 sam long, Wee prepied by ele: Secharge machining pale to he econ
<iecrion ftom asexsruded bas of Gompm Mi PX, Vsing these specimens consmar stain mee
compression testing was pesformed from ei sompernane to 870°C in mist engineering sain
rates | W045. Testing was tial ot 2270 rhe 28 650° tent a 30%
sega fo the 10°C 1 STC

DYNAMIC COMPRESSIES/TESTY AT ROOM AND ELEVATED TEMPERAURES

‘A Split Hopkinson Patste“Bae (SHE) is employed 0 conduct the room and elevated
temperature high aifai.rae compression tests, The developunaut and analysis of the SHPB ean
be found elsewhere (Folléasboe. 1985; Gray. 2000). The SHPB facility at CWRU is shown in
Figure dad complies striker, ned and transmit bar made frm 19.08 min diameter
hig irene aking stel and having nominal yield strength of 2500 MPa, The ste:
spproniiubely 0.508 i long, whils the incident ond transmitted bars ate 1.524 m long, The
saiker bari ulead sing an ar opersisd gas yun. pair of senin gages (Messursments
Group WK-06-250BF-10C) ate stalegiclly ausched on eau of the incident and tansained

bars and ate used in combination wick a Wheatstone bridge citeult conaeeted wich diferential
aunplficr (Lektronix SA22N) and a digital osci:loscope (Tektronix TDS 420) to nvoaitor the
souin during the test. The impact vecity ofthe strikor har wns varied from 7 to 15 mvsoe so a8
(w obiain strain cates inthe range 12005" tn 2500"

Projectile lncident bar Stein gape
Gas i . tke ‘Shock absober
un J Bearings // specimen ‘reaper bar
=

=

[Wat sone Bdge’. Dierentia
Girt i__Ampliier

| High Speed

Power Supp _————e Sebescpe

Figure 2: Schomatio of Spiit:Hopkiason Bpr ised to condnet the dynamic compression tests.

For the deeminaion of pam Now chanetrscs of Gamma Mit PX, spinal

compression fabs (4.76 inn limotss by 2.35 mm ihickd were machined vat a 12.7 ram

thane bar THe tlitely salle of specimens Slow a set amplicon (ato of
ss in the salto shin ba) uF 16, which was Fou A Be noes to den the
spcelracns a Sigh ize smts in view ofthe high yie\d-stress of CGarnma Met PX alloy. Prior a
the ite Be sures (hs) of the specinans wer roid aud ‘aed at, Forte
coum tier experimen mlycwam grea i apted Feral in oder to minimize
friction at the Specimenbae ‘interface.
Dowrinaicn of dame rapnse of a nae s level fpr using he SHPB 2
halen asks primes doc the fs a heating he specie, while in coat
‘whe ts em in hein teen of he nie ané uote bes. "This a 9 @
rapes iets By which nw af late modus and deny. oh
of which ae Soo Los) ith oupestis, Taus in ene 0 ohtsnaccraearese-stin
cures, «concen needs ) be applet w He sraivge Mvmls to amps for ie
teapertre pend latina ove elit aad lato elu” coisig the
‘superar grein he bars. Oe a 0 sets problem so hg ho seinen alone to
the evi tenes and hg th od brs cotati Pe spine, Tose,

cold cons ito he br cone
in etc with he einen, espace oes sempre ha orducion he ts

the problem encountered with this procedure is

Figare 3 shons a Finite clement simulation of hes, ecinduetion ithe specimen and the bur
escenbly using he commer FEM package ABKOUSY (2h). A nal peice of
S04 Is pescribd othe spsimen, The ali si te tenpcrare grater avlons
‘thn he peimen iediy ae tat pe rug i ont

Several approaches have been used in the Ygiboeviowe these problems. Amoagst ikem an
spywogeh based on mochanical devices is fag the tas in contact with the sposimen just before
the arrival of the pulse atthe spel pic as found wide apcead ua (efor example, Pane
et uf, 1983, and Lenuox'and Rath, 1998), However, synchnaization of time for he
movement of the bart with themival of the loading pulse bas remained problematic, Cher
setbods include the use of Jaci718 bars in testing up to 600°C, and the use of Tong

slurninur oxide bars it Gobyactity sre] bass foe testing upto 150°C: (Pllamsbee, 1985}.
Bs 2

‘Temperature (°C)

Figure 3: ‘Temperance distibucion inthe specimen as a function of tme after the specimen is
brought fn coma withthe har,

The schematic yout ofthe high tempera tess de up ar CWRU is shown in Figure 4). In
dation tothe convencoual HP, f¥6ait.cooedinffaed spot heaters re used as the heating
elements. The TR spot hewers have ccc oot sick! which conceraats the heat fx atthe
cal paint (0.25 inch diaméterj as High’ ai'450 watts per myuime inch, Th arder to overcome the
problem of coi contace ties, bebviéen the bars and the specimen and daus allow sufficient time
for the movement of che. bas the specimen is sandwiched between cwo WO insorts and the

wssemblycanpsving Dents ind the ecimen is heated othe dered le emperlure. The
WC insects are dejpedahos marched 10 the incident and the tonsmitiee bars, and hence do not
cub he detec’ aud che taasaed wave profiles

‘uit pri. £6 soadicing dhe west the inertpecimen-invert assembly is heated up to the desired
sezaperara jal (lly $0-100°C higher han the test enpertue). Tae bars ae then brought
roanually in comact withthe asoubly, Ths specimen is hold borwcen the two insta by
thermascuple wires predefre to » up-shaps, Cis allows fie radial expansion of the