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Evolution of MnS inclusions in Ti-bearing X80 pipeline steel
J our na lo fI r onandS t e e lRe s e a r ch, I n t e r na t i ona l２４ (２０１７) ６５４－６６０
Evo l u t i ono fMnSi nc l us i onsi nTi Ｇ be a r i ngX８０p i l i nes t e e l pe Ze Ｇ anLv１ ２ , Hong Ｇwe iNi１ ２ ∗ , HuaZhang１ ２ , Cheng Ｇ songL i u１ ２ ∗ ∗ ,
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TheS t a t eKeyLabo r a t o r fRe f r a c t o r i e sand Me t a l l u r i ve r s i t fSc i enc eandTe chno l ogy, Wuhan４３００８１, yo gy, WuhanUn yo Hube i, Ch i na ２ KeyLabo r a t o r o rFe r r ousMe t a l l u r s ou r c e sUt i l i z a t i ono fMi n i s t r fEduc a t i on, WuhanUn i ve r s i t fSc i enc eand yf gyandRe yo yo i, Ch i na Te chno l ogy, Wuhan４３００８１, Hube １
ARTICLEINFO
ABSTRACT
Keywo rds: Ti t an i umＧ be a r i ngX８０ i l i nes t e e l p pe I nc l us i on Ti t an i umc a r bo su l f i de Mangane s esu l f i de Tr ans f o rma t i on Di f f us i on
S t ud i e sshowt ha tmangane s esu l f i de ( MnS) i nc l us i onsi np i l i nes t e e la f f e c tt hel a t e r a lpe r f o rmanc eo f pe s t e e li ni t sr o l l i ngde f o rma t i on, a s we l la st hehyd r ogen Ｇ i nduc edc r a ck i ngandsu l f i des t r e s sc o r r o s i on c r a ck i ngr e s i s t anc epe r f o rmanc e．Toi nh i b i tt hep r e c i i t a t i ono f MnSandi t se f f e c tonp i l i nes t e e l, a p pe i ngexpe r imen tandad i f f us i onc oup l eexpe r imen t, wh i chi nve s t i t edt heevo l u t i ono fMnSi nc l u Ｇ quench ga s i onsi nTi Ｇ be a r i ngX８０p i l i nes t e e l, we r ec onduc t ed．Theexpe r imen t a lr e su l t sshowt ha tt het r ans f o r Ｇ pe ma t i ono ft heMnSi nc l us i onsdur i ngs o l i d i f i c a t i oni sa sf o l l ows: MnS→t i t an i umsu l f i de (Ti S) →Ti ４C２S ２． Thet r ans i t i ont empe r a t ur e so fMnSt oTi SandTi St oTi r e１６７３and１２７３ K, r e spe c t i ve l y, and ４C２S ２a t heove r a l ls i z eo ft hesu l f i dede c r e a s eda swe l l．The rmodynami cc a l cu l a t i onr e su l t sc on f i rmt ha tt het r ans i Ｇ t i ont empe r a t ur e so fMnSt oTi SandTi St oTi r e１６２３and１２０３K, r e spe c t i ve l hesu l f ur y．Whent ４C２S ２a c on t en ti nt heX８０p i l i nes t e e li s０ ００１５％ , a l lt hesu l f uri nt hes t e e lc anbec onve r t edi n t oTi i t h pe ４C２S ２w at i t an i umc on t en to fmo r et han０ ０２％．
１． I n t r odu c t i on MnSi np i l i nes t e e lha sas i i f i c an timpa c ton pe gn t oughne s s, we l d i ng p r ope r t a n d s t r e s sc o r r o s i on y [１,２] c r a ck i ngpe r f o rmanc eo ft hes t e e l ．Banded MnS i nc l us i onsa f t e rr o l l i ngp r o c e s si nc r e a s et hehyd r o Ｇ Ｇ i nduc edc r a ck i ng ( HIC) andsu l f i des t r e s sc o r Ｇ gen r o s i onc r a ck i ng (SSCC) s ens i t i v i t ft he s t e e l, yo wh i chr e su l tf r om hyd r ogenen r i chmen tandc aus e mi c r oc r a cksandemb r i t t l emen t, e spe c i a l l t hc o r Ｇ ywi r o s i vega s e ssucha sH２SandCO２i nna t u r a lga s．To r educ et hee f f e c to fMnSi n c l u s i onont h ep r op e r t i e so f i e l i n es t e e l, Sc on t e n ti ns t e e ls hou l db er e du c e dt o p p (３０－５０) ×１０－６ , e v e nb e l ow１０×１０－６ ．Add i ngc a l c i Ｇ um o rr a r ee a r t hi n t o mo l t ens t e e lt o mod i f he yt mo r l ogy, s i z eand c ompo s i t i on o f MnSi nc l u Ｇ pho s i onswa spr ovedt obeano t he re f f e c t i vewayt osup Ｇ [ , ] r e s st heHICandSSCCs ens i t i v i t fs t e e l３ ４ ． p yo Pr ev i ous l l t e rna t i ves o l u t i onswe r ei n t r o Ｇ y, twoa duc edt osupp r e s st henega t i vee f f e c t so fsu l f i dei n Ｇ , achemi c l us i ons,i e． c a li nc l us i ono fshapec on t r o l (c a l c i umo rr a r ee a r t ht r e a tmen t) a ndt h ep r odu c t i on , Ph． ∗ Co r r e spond i ngau t ho r．Pr o f． D． EＧma i laddr e s s: n i hongwe i ３２０＠s ohuc ． om (HW ．Ni) ． ∗∗ Co r r e spond i ngau t ho r．Ph． D． EＧma i laddr e s s:l i uchengs ong＠wus te ．duc ． n (CS． Li u) ．
o fs t e e l s wi t he x t r a Ｇ l ow s u l f u r (b e l ow ０ ００２％) ５Ｇ７ ． [８] Moone ta l i nve s t i t edt hee f f e c t so fCaadd i t i on ga andCa/Sr a t i oon HICr e s i s t anc e．Expe r imen t a lr e Ｇ , su l t sc l e a r l r o v e dt h a tf o r m a t i o no fC a S i n s t e a d yp o fMnS, byCaadd i t i oni se f f e c t i vei nimp r ov i ngt he HICr e s i s t anc eandt h i si ss t r ong l e l a t edt ot hei n Ｇ yr c l us i onshape．HIC r e s i s t anc ei nc r e a s ed whent he Ca/Sr a t i o wa sh i rt han１ ２５andi t wa scon Ｇ ghe f i rmedt ha tt h i sva l uei sr e l a t edt ot hes t o i ch i ome t r i c [ ] r a t i obe twe enCaandS．Xue ta l ９ s t ud i edt hede s Ｇ u l f ur i z a t i onbehav i o ro fCaOＧ s a t ur a t eds l ag．Re su l t s showedt ha tde su l f ur i z a t i one f f i c i enc fCaOＧ s a t u Ｇ yo r a t eds l ag wa si n f l uenc edbyt heamoun to fr e s i dua l l i i ds l agandi t ssu l r t i onab i l i t qu phurabso p y．CaOＧ s a t ur a t eds l agha sah i rsu l i s t r i bu t i onr a t i o ghe phurd bu tal owe rappa r en tr a t econs t an tt hanl i i ds l ag qu i nt hede su l f ur i z a t i onr e a c t i on．Whent hes l a ompo Ｇ gc s i t i on wa s６２ ５％ CaOＧ ２２ ５％ Al２O３Ｇ ５％S iO２Ｇ １０％ CaF２ , t hed e s u l r i z a t i onr a t i owa sh i rt han８８％ phu ghe andt hec on t e n to fs u l h u rw a s l o w e rt h a n１ ０×１ ０－６ , p wh i chr educ e st heimpa c to fsu l f i de sont he HIC , r f o rmanc eo fp i l i nes t e e l．Howeve r p r ev i ous pe pe [
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Re c e i ved１２Sep t embe r２０１６; Re c e i vedi nr ev i s edf o rm３０Novembe r２０１６; Ac c ep t ed２De c embe r２０１６ Ava i l ab l eon l i ne１５June２０１７ / , , １００６ Ｇ ７０６X Copy r i tⓒ２０１７ Th ee d i t o r i a lo f f i c eo fJ ou r n a lo fI r ona ndS t e e lRe s e a r c hI n t e r n a t i on a l． Pub l i s h e dbyE l s e v i e rL imi t e d．Al lr i t sr e s e r v e d． gh gh
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
wo rkswe r ema i n l o cus edon MnS mod i f i c a t i onby yf c a l c i umt r e a tmen to rr educ t i ono fSc on t en ti nt he s t e e l, andf ews t ud i e shavebe enc a r r i edou tont he t r ans f o rma t i on o f MnS by Tit r e a tmen t, wh i ch c ou l di nh i b i tt henega t i vee f f e c to fMnSandimp r ove t hequa l i t fp i l i nes t e e l． yo pe Theso l i ds o l u t i onands eg r ega t i ono fTi Ｇ be a r i ng i nc l us i onsi nTia l l oys t e e l sc anr e t a r daus t en i t er e Ｇ , c r s t a l l i z a t i o na n d r a i n r o w t h． I nt h i sw a af i n e y g g y r a i n mi c r o s t ruc t u r ec ou l d bea ch i evedt oenhanc e g [ , ] t hes t e e ls t r eng t h１０ １１ ．Thef o rma t i ono ft i t an i um c a rbosu l f i de (Ti４C２S２ ) p r e c i i t a t e s, wh i chc ani n Ｇ p h i b i t MnS pr e c i i t a t i on and s i i f i c an t l r ove p gn y imp t heHICandSSCCr e s i s t anc eo fp i l i nes t e e l s, i s pe ano t he rimpo r t an tr o l et ha tt he mi c r oa l l oy i ng e l e Ｇ men tTip l aysi np i l i nes t e e l s． I nt h i ss t udy,t oi n Ｇ pe h i b i tt he pr e c i i t a t i ono f MnSandi t sun f avo r ab l e p e f f e c tonp i l i nes t e e l, r e s e a r chont heevo l u t i ono f pe MnSi nc l us i onsi nTi Ｇ be a r i ngX８０p i l i nes t e e lwa s pe c onduc t ed． Change si nt hemo r l ogyandc ompo s i Ｇ pho t i ono ft hei nc l us i onsi nt he X８０ s t e e l we r eana Ｇ l z ed, andt het r ans f o rma t i on p r o c e s sand me cha Ｇ y n i smo fMnSt oTi４C２S２c onv e r s i oni nT i Ｇ b e a r i ngX８０ i e l i n es t e e lwa sa l s oi nv e s t i a t e da ndd i s c u s s e d, a l ong p p g wi t ht heo r e t i c a lt he rmodynami cana l s i s ． y
２．Exp e r imen t a l ２ １． Quench i ngexpe r imen t Fo racomp l e t et r ans f o rma t i ono fMnSt oTi４C２S２ i ns t e e l, t hecon t en to ft i t an i um wa ss e l e c t ed a s [ ] ０ ０３wt ％ wh i l et ha to fSwa s０ ００１５wt ％ １２Ｇ１６ ． Us i ngava cuumi nduc t i onf urna c e, Ti Ｇbe a r i ng X８０ ( ) i l i nes t e e li ngo t １０kg wa sp r epa r ed; t hef i na l p pe compos i t i ona swe l la st heAme r i c anPe t r o l eumI n Ｇ s t i t u t es t anda rdso fX８０ p i t e e l (APISpe c５L, pes , ) ５ t h ２０１２ a r el i s t edi nTab l e１． F i vei n i t i a ls amp l e s (１kgf o re a chone) we r et akenf r omt hei ngo tand r e Ｇme l t edi nana l umi nac ruc i b l ei na mo l ybdenum d i s i l i c i def urna c eunde ra r r o t e c t i on．Af t e rad Ｇ gonp us t i ngt he ma i ns t e e lcompos i t i onsa t１８７３ Kf o r j ０ ５h,i n i t i a ls amp l e swe r ewa t e rquencheda t１８７３, １６７３, １４７３, １２７３, and１０７３K, r e s e c t i v e l i １)． p y (F g Thr e eme t a l l og r aph i cspe c imens(１０mm×１０mm× １０ mm) we r et akenf r ome a chi n i t i a ls amp l ef o ran a l Ｇ s i s, a tpos i t i onsi nd i c a t edi nF i ２．Thef i na lcomＧ y g i t i onso fX８０p i l i nes t e e li ngo twe r eme a sur ed pos pe byi nduc t i ve l c o u l e d l a s m ae m i s s i o ns e c t r o m e Ｇ y p p p ( ) , , t r I C P Ｇ A E S ． T h em o r h o l o s i z e n u m b e r a n d y p gy chemi c a lcompos i t i ono fi nc l us i onsi nt heme t a l l og r Ｇ
Tab l e１ Chemi c a lc ompo s i t i onso fexpe r imen t a lX８０s t e e landAPIs t anda r ds (wt ％ ) I t em
C
S i
Mn
S
P
Ti
N
Expe r imen t a ls t e e l ０ ０２６ ０ ２８ １ ６ ０ ００１６ ０ ００１５ ０ ０３２ ０ ００２０ ) APISpe c５L (max． ０ １２ ０ ４５ １ ８５ ０ ０１ ０ ０２ ０ ０６ － No t e: a—Ni＋V＋Ti≤０ １５％ ; b—Cu≤０ ５％ , Ni≤０ ５％ , Cr≤０ ５％ , Mo≤０ ５％ , B≤０ ０００５％．
F i １． Tempe r a t u r ecu r veo fme l t i ngandquench i ngf o r g s t e e ls amp l e s．
６５５
TO
０ ００６２ －
Ot he r － a, b
F i ２． Samp l i ngpo s i t i onso fi n i t i a ls amp l e s． g
i nes t e e l(５００g) andMnS (５０g) we r ep l a c edi n t oan a l umi na c ruc i b l ei nah i Ｇ t empe r a t ur er e s i s t anc e gh aph i cspe c imenswe r eme a su r edbys c ann i nge l e c t r on f urna c eunde ra r r o t e c t i on．Thes amp l e s we r e gon p mi c r os copy (SEM) andene r i spe r s i vespe c t r ome Ｇ f gyd i r s the a t eda t１８７３Kf o r１h, andt hencoo l eddown t r y (EDS) ． t o１４７３Ki nf urna c e, andf i na l l t e r． yquenchedbywa S c h e m a t i co f t h ed i f f u s i o nc o u l ee x e r i m e n t i ss h o w n p p ２ ２．Diffu s i onc oupl eexpe r imen t i nF i ３．Av e r t i c a lc r o s s Ｇ s e c t i ono ft hequ e n c he ds amp l e g Toc l a r i f heevo l u t i onp r o c e s sandme chan i smo f wa yt s mi r r o r Ｇ l i shed wi t hS iCＧ coa t eds andpape rand po MnS→ Ti S→ Ti４C２S２ t r ans i t i oni nT i Ｇ b e a r i ng X８０ d i amondpa s t e．The mo r l ogyandchemi c a lcomＧ pho i e l i n es t e e l, ah e a tt r e a tme n te xp e r ime n twa sd e s i e d pos p p gn i t i onso ft he MnSl aye rand X８０s t e e lsubs t r a t e a ndc a r r i e dou tbyd i f f us i onc oup l eme t hod．X８０p i l Ｇ we pe r ea l some a sur edandana l z edbySEMＧEDS． y
６５６
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
F i ３． Schema t i co fd i f f us i onc oup l eexpe r imen tf o rTi Ｇbe a r Ｇ g i ngX８０p i l i nes t e e l． pe
３．Re s u l t s
３ １．Change si n mo rpho l ogy andc ompo s i t i onof i nc l u s i on si nX８０s t e e l
t e e ls amp l e swe r eana l z edbyus i ngnon Ｇ quencheds y me t a l l i ci nc l us i onau t oma t i cana l i sso f twa r e (ImＧ ys age Ｇ r oP l us), a sshowni nF i ５．Dur i ngso l i d i f i c a Ｇ p g t i on, su l f i dei nc l us i onsma i n l i s t edo fMnSand ycons Ti Sf r om１８７３t o１６７３K． Pe r c e n t a e so fMnSandTi S g de c r e a s edandi nc r e a s edr e spe c t i ve l t ht het emＧ y wi r a t ur ede c r e a s i ngf r om１６７３t o１４７３K, wh i chi n Ｇ pe d i c a t edt ha tpa r to ft he MnSt r ans f o rmedi n t o Ti S． Asso l i d i f i c a t i oncon t i nued, Ti４C２S２ begant opr e c i pＧ i t a t ewhent hequench i ngt empe r a t ur ede c r e a s edt o １４７３K．Ast hequench i ngt empe r a t ur ede c r e a s edt o １２７３ K, bo t ho ft hepe r c en t age so fMnSandTi Sde Ｇ c r e a s edf ur t he r, whe r e a st ha to f Ti４C２S２ i nc l us i on i nc r e a s eds i i f i c an t l r eove r, t hepe r c en t ageo f gn y．Mo Ti４C２S２i nc r e a s edt o６２％ andt ha to fMnSde c r e a s ed t o２４％ whent hequ e n c h i ngt emp e r a t u r ewa s１０７３K．
Thenumbe r so fsu l f i de si n５０f i e l dso fv i ewa td i f Ｇ f e r en tquench i ngt empe r a t u r e sa r el i s t edi nTab l e２． Wi t hd e c r e a s i ngt h equ e n c h i ngt emp e r a t u r e, t h eamoun t , o fs u l f i d e si nc r e a s edg r adua l l spe c i a l l r i ngt emＧ ye ydu r a t ur ef r om １８７３t o１６７３ K．Thepe r c en t age so f pe d i f f e r en t Ｇ s i z ed su l f i dei nc l us i onsi nt he s t e e la f t e r i ng a td i f f e r en tt empe r a t u r e sa r e showni n quench F i ４．Ast hes o l i d i f i c a t i on p r o c e s sp r o c e eded, t he g su l f i de i nc l us i on s i z e de c r e a s ed g r adua l l t e r y．Af i nga t１８７３K, mo r et han７０％ o ft hesu l f i de s quench we r el a r rt han５μm, andapp r ox ima t e l ft he ge y２％ o su l f i dei nc l us i onswe r esma l l e rt han２μm; whent he i ngt empe r a t u r ede c r e a s edt o１０７３ K, ne a r l quench y Fi ５． T e sa ndr a t i o so fs u l f i d e si ns t e e la f t e rquench i nga t yp g ７０％ o ft hei nc l us i onswe r esma l l e rt han２μm． d i f f e r en tt empe r a t u r e s． Thenumbe ra ndr a t i oo ft h es u l f i d ei n c l u s i on si nt h e Mo r l ogyo ft i c a li n c l u s i on si ss howni nF i ６． pho yp g Tab l e２ Thema o rs u l f i d ei n c l u s i on sa t１８７３Ka r es i ng l es r i Ｇ j phe Numb e ro fs u l f i d e si n５０f i e l d so fv i ewa td i f f e r en tquench i ng c a lMnS pa r t i c l e so f５－１０ μm; when quencheda t t empe r a t u r e s １６７３K, t hema o rsu l f i de sa r e ( Mn,Ti)S, andt he j Tempe r a t ur e/K １８７３ １６７３ １４７３ １２７３ １０７３ c ompoundi n c l u s i oni ss u r r ound e dbyanou t e r(Al,T i)O Numbe ro fsu l f i de s １３ ４７ ５９ ６８ ８５ l a e r．Thes i z eo f( Mn,Ti)Sando t he rcompoundi n Ｇ y c l us i onsi s３－５ μm．Wi t ht hequench i ngt empe r a Ｇ t ur ede c r e a s i ngt o１４７３ K, t he ma o ri nc l us i oni sa j compoundi n c l u s i onwi t h ( Mn,T i)Sa sc o r e, s u r r oun Ｇ ( , ) , d e dby Al S i O．Af t e rquench i nga t１２７３ K su l Ｇ f i de schangedi n t oT i u r r ound e dby ( Mn,T i)S, ４C ２S ２s whe r e a st hes i z ede c r e a s edt oabou t２ μm． I nadd i Ｇ t i on, mo r esma l l Ｇ r t i c l eTi４C２S２ p r e c i i t a t ed when pa p i nga t１０７３ K．Al ong wi t hso l i d i f i c a t i on, i t quench wa si n f e r r edt ha tt het r ans f o rma t i on pa t ho f MnS wa sMnS→Ti S→Ti４C２S２ , andt ha tt hesu l f i des i z e de c r e a s eds i i f i c an t l gn y．
３ ２．Ob s e rva t i on sa ti n t e r ac eb e twe en MnS and f s t e e lbydi u s i onc oupl eexpe r imen t f f
F i ４． Su l f i des i z ed i s t r i bu t i ona td i f f e r en tt empe r a t u r e s g du r i ngc oo l i ngp r o c e s s．
F i ７showst hee l emen tl i nes c ann i ngr e su l t sa t g t hei nt e r f a c ebe twe en MnSandX８０s t e e lma t r i x． I t
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
６５７
(a) １８７３K; (b) １６７３K; (c) １４７３K; (d) １２７３K; (e) １０７３K．
F i ６． Mo r l ogyo ft i c a li nc l us i onsi ns t e e la f t e rquench i nga td i f f e r en tt empe r a t u r e s． pho yp g
F i ７． El emen tl i nes c animageo fMnS Ｇ subs t r a t etwo Ｇpha s ei n t e r f a c e． g
i nd i c a t edac l e a ri n t e r f a c e, andamu t ua lpene t r a t i on i sa l soobs e r vedbe twe en MnSands t e e l．Thepene Ｇ t r a t i on Ｇ l aye rt h i ckne s si s abou t １５０ μm．Re su l t s showedt ha tt hec on t en t so fMnandSde c r e a s eds i Ｇ g n i f i c an t l nt he MnS Ｇ t o Ｇ s t e e lsubs t r a t ed i r e c t i on． yi Thecon t en t so fTia l s oshowedade c r e a s i ngt r end f r om t he X８０ s t e e l ma t r i xt ot he MnS d i r e c t i on, wh i chi nd i c a t edt ha tTii nt hes t e e ld i f f us edt ot he MnSs i de．Thec on t en to fTii n MnSne a rt he MnS Ｇ s t e e li n t e r f a c ei nc r e a s edt oabou t０ ００１５％． F i ８i l Ｇ g l us t r a t e st heSEM mi c r og r apho fsu l f i de sne a rand f a rf r om t hei n t e r f a c ebe twe en MnSand X８０sub Ｇ s t r a t e．Compo s i t i onso ft hei nc l us i onsa r eshowni n Tab l e３．Re su l t sshowedt ha ti nt heX８０s t e e lsub Ｇ s t r a t e, Ti４C２S２ o rab i na r l f i deo f MnS ＧTi４C２S２ ysu r e c i i t a t edne a rt hei n t e r f a c ebe twe ent he MnSand p p X８０p i l i nes t e e l, and MnSi nc l us i onsmo s t l i s Ｇ pe yex t edawayf r omt hei n t e r f a c e．
４．Di s c u s s i on ４ １．Crys t a ls t ruc t ur et ran s o rma t i on mode l of f MnSt oTi４C２S２ Pr ev i ouss t ud i e sont het he rmodynami ca s s e s s Ｇ men to ft heFe ＧMn ＧTi ＧCＧSs s t e ms h o w e d t h a tw h e n y t hewe i tr a t i oo fS/Tiwa sl e s st han２, Ti S wa s gh [ ] expe c t edt op r e c i i t a t ep r i o rt o MnS１７ ．Dur i ngt he p r ima r t ageo fso l i d i f i c a t i on, MnSt r ans f o rmedi n Ｇ p ys t oTi Sbyt he mu t ua ld i f f us i ono f Mnand Ti．EDS r e su l t swe r esuppo r t edbye l e c t r onba ck Ｇ s c a t t e rd i f Ｇ f r a c t i on (EBSD) da t a, andi ti nd i c a t edt ha tt heTi S f o l l owsa NiAs Ｇ t r t a lun i tc e l l (spa c eg r oup ypec ys P６３ /mmc) wi t hl a t t i c epa r ame t e r so fa＝０ ３２９nm [ ] andc＝０ ６３９nm １８ ．TwoTia t omsex i s ti nt he (０, ０, ０) pos i t i onsandano t he rtwoSa t omsi nt he (２/３, １/３, １/４) pos i t i ons．Tia t omsa r ec ent e r edi nad i Ｇ
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
６５８
(a) Ne a ri n t e r f a c e (２０μm); (b) Fa rf r omi n t e r f a c e (５００μm) ．
F i ８． SEM mi c r og r apho fsu l f i de sne a randf a rf r omi n t e r f a c ebe twe en MnSandX８０s t e e l． g Tab l e３ EDSana l s i sr e su l t si nF i ８ (ma s s％ ) y g Po s i t i on
Ti S
Ti ４C２S ２
Al２O３
S iO２
－
１１ ７
８２ ６
５ ４
０ ３
－
５ ６
８８ ７
５ ２
０ ５
１１ ８
－
７ ５
２ ７
MnS
１
７４ ６
３
６４ ９
５
９０ ４
７
８２ ７
２ ４ ６
７８ ０
１２ ４ １８ ５ ３ ８ ８ ５
－ －
－ －
８ ２
１０ １ ４ ６ ７ ９
new T i n i tc e l li sf o rme dbyt heCa t omi nT i C ４C ２S ２u r ep l a c i ngf ourva c anc i e si nTi S, a sshowni nF i ９． g
４ ８
６ ５ １ ２ ０ ９
s t o r t edoc t ahed r onf o rmedbys i xSa t omsandt he su l f uri ons haveat r i o n a lc o o r d i n a t i o n w i t h t he g t r ans i t i on me t a l．The S a t omsf o rm c l os e Ｇ a c k e d p l aye r st ha ta r ea r r angedi nahexagona ls t a ck i ngs e Ｇ [１９] e ． quenc Ti４C２S２i sat he rmodynami c a l l t ab l ec ompound ys t ha tappe a r seveni nu l t r a Ｇ l ow c a rbons t e e l s．EBSD ana l i sshowst ha tTi４C２S２ ha sahexagona lc r t a l ys ys s t ruc t ur ewi t hl a t t i c epa r ame t e r so fa＝０ ３２nmand c＝１ １２nm．Thel a t t i c epa r ame t e r so fTi４C２S２ ob Ｇ t a i ned by EBSD ag r e e wi t ht ho s e ob t a i ned by [ ] Ba l l２０ ．Ti４C２S２c r t a l l i z e sa c c o r d i ngt ot heCr２AlC ys r o t o t c eg r oup P６３ /mmc) ．Ca rbona t oms p ype (spa o c cupyt hepo s i t i ono f (０, ０, ０) and (０, ０, １/２), su l f ura t omso c cupyt hepo s i t i ono f(１/３, ２/３, ３/４) and (２/３, １/３, １/４), andt i t an i um a t omso c cupy t hepos i t i ono f(１/３, ２/３, z), (２/３, １/３, z＋１/２), (２/３, １/３, －z) and (１/３, ２/３, －z＋１/２), whe r e [ ] z equa l st o０ ０９９８２１ ． TiC p r e c i i t a t edi nc a rbon Ｇ r i cha r e a sdu r i ngt he p l a t eso l i d i f i c a t i on．TheTi Cc r s t a l i sac u b i cc r s t l y ya , s s t e m w i t ha s a c e r o u o fF m Ｇ ３ m w h i c hb e l o n s y p g p g t o a sod i um ch l o r i de Ｇ t r t a ls t ruc t u r e．Ti S ype c ys t r ans f o rmedi n t o Ti４C２S２ byi s omo r t i t u Ｇ phoussubs t i on．Be c aus eTi SandTi４C２S２ haveas imi l a rc r t a l ys s t ruc t ur e, a t omo c cupa t i onandl a t t i c epa r ame t e r, a
Fg ９． Fo rma t i ono fTi n i tc e l lf r om Ti SandTi C． ４C ２S ２u
４ ２．The rmodynami c ana l i sof t i t an i um i nc l u Ｇ ys s i on si nTi Ｇ b ear i ng X８０pipe l i nes t e e l
Theso l ub i l i t t ao fTiC, TiN, MnS, Ti Sand yda Ti４C２S２f r omso l u t eTi, Mn, S, andCi nt heFe ＧCＧ [ ] S ＧMn ＧTia l l oysys t ema r er e r e s e n t e di nT ab l e４２２Ｇ２５ , p andt hee s t ima t edt empe r a t ur e dependenc eo ft he so l ub i l i t r oduc t sf o r TiC, TiN, MnS, Ti S and yp Ti４C２S２i sp l o t t edi nF i １０．Theso l ub i l i t oduc t s g ypr o ft he s e compoundsf o l l ow t he o rde ra s TiN ＜ TiC０５S０５ ＜ Ti S＜ MnS＜ TiC be l ow １２４５ K．The t r ans i t i ont empe r a t ur e so f MnSt o Ti Sand Ti St o Ti４C２S２a r e１５５０and１２４５K,r e s e c t i v e l Th i sa r e e s p y． g wi t ht he p r e c i i t a t i on s equenc eo fsu l f i de si n Ti Ｇ p [ ] be a r i ngs t e e l s２６ ． I so t he rma ls e c t i onso fs u l f i d ep r e c i i t a t e sa t１４７３K p i nt heFe Ｇ ０ ００２５CＧ ０ ００３NＧ １ ５Mn ＧS ＧTis t em a r e ys showni nF i １ １． T h ec a l c u l a t e dr e s u l t sa r e e w e l l g g wi t ht heobs e r vedp r e c i i t a t e t e s ． Wh e n t h e s u l f u r p yp cont enti nX８０p i l i nes t e e lwa s００１５％ , a l lsu l Ｇ pe
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
Tab l e４ Func t i ono fp r e c i i t a t e ss o l ub i l i t ns t e e l p yi Compound TiN
MnS
Pha s e
L i i d qu γ
α, δ
L i i d qu
So l ub i l i t oduc t ypr
l ogK TiN ＝l ogw [Ti]w [N] ＝ －１４０００/T ＋４ ７ l ogK TiN ＝l ogw [Ti]w [N] ＝ －１３８６０/T ＋３ ７５ l ogK TiN ＝l ogw [Ti]w [N] ＝ －１６６５０/T ＋４ ８ ogw [ Mn]w [S] ＝ －６０５０/T ＋３ ４ l ogK MnS＝l
α, δ
l ogK MnS＝l １ ogw [ Mn]w [S] ＝ －１１２００/T ＋５ l ogK MnS＝l ogw [ Mn]w [S] ＝ －１２０００/T ＋４ ９
γ
Ti S
L i i d qu γ
l ogK TiS＝l ogw [Ti]w [S] ＝ －１６５５０/T ＋６ ７５
Ti ４C２S２
L i i d qu α, δ
－ l ogK TiC０５S０５ ＝l ogw [Ti]w [C]０５w [S]０５＝ －１５３１０/T ＋６ ０３ －
γ
l ogK TiC ＝l ogw [Ti]w [C] ＝ －７０００/T ＋２ ７５
Ti C
α, δ γ
L i i d qu α, δ
－
－
－
l ogK TiC ＝l ogw [Ti]w [C] ＝ －９５７５/T ＋４ ４
F i １０． Tempe r a t u r edependenc eo fs o l ub i l i t r oduc t sf o r yp g Ti S, Ti C０５S０５ , TiN, Ti C, and MnS．
F i １１． Ca l cu l a t edpha s ed i ag r amo fsu l f i dep r e c i i t a t e sa t p g １４７３Ki nFe Ｇ ０ ００２５CＧ ０ ００３NＧ １ ５Mn ＧS ＧTisy s t em us i ng s o l ub i l i t r oduc t s． yp
f i de si nt hes t e e lc ou l d bec onve r t edi n t o Ti４C２S２ wi t hat i t an i umc on t en to fmo r et han０ ０２％．Wi t h t hei nc r e a s ei nsu l f u randt i t an i um c on t en t si n X８０ i l i nes t e e l, t hesu l f i dei ns t e e lwa sde t e rmi neda s p pe
６５９
Ti４C２S２ ． Fa c t Sa ec a l c u l a t i onr e s u l t sf o rsu l f i dep r e c i i t a t e s g p i nTi Ｇbe a r i ngX８０p i l i nes t e e la r eshowni nF i １２． pe g Duet ot hes t r ong a f f i n i t f Tiand N, TiN and yo MnSp r e c i i t a t eddur i ngt hee a r l t ageo fso l i d i f i c a Ｇ p ys t i oni nTi Ｇbe a r i ngX８０p i l i nes t e e l．Ast het empe r Ｇ pe a t ur ede c r e a s edt o１６２３and１２０３ K, pa r to f MnS i nc l us i onschangedt oTi Sandt hent oTi４C２S２ , r e Ｇ spe c t i ve l ． T h em a x i m u m r e c i i t a t i o n u a n t i t a n d y p p q y r e c i i t a t i ont imef o r MnSand Ti４C２S２ dependon p p t hesu l f urandn i t r ogencon t en t si nt hes t e e l．Ti Sand Ti４C２S２ begant op r e c i i t a t eon l f t e rt hef o rma t i on p ya o fTiN．Thet r ans f o rma t i ont empe r a t ur e so fMnSt o Ti SandTi St oTi４C２S２ we r e１６２３and１２０３ K, r e Ｇ spe c t i ve l i chapp r ox ima t e l r e edwi t ht heex Ｇ y, wh yag r imen t a lr e su l t s． pe
F i １２． Ca l cu l a t edma s sf r a c t i ono fsu l f i dep r e c i i t a t e si n p g Ti Ｇbe a r i ngX８０p i l i nes t e e l． pe
５．Conc l u s i on s (１) Ast het empe r a t ur ede c r e a s e sf r om １８７３ K t o１０７３ K dur i ngso l i d i f i c a t i on, su l f i de si nt heX８０ : s t e e lchangeda l ongt hepa t h MnS→Ti S→Ti４C２S２ andt hes i z eo fsu l f i de sde c r e a s edg r adua l l y． (２) Ti SandTi４C２S２ haveas imi l a rc r t a ls t ruc Ｇ ys t ur eanda t om oc cupa t i on, wh i ch, i nt heo r Ｇ y, con t r i bu t edt ot het r ans f o rma t i ono fTi Si n t o Ti４C２S２ byi somo r t i t u t i on． phoussubs (３) Whent hesu l f urandt i t an i umcon t en t si nt he X８０ p i l i nes t e e l we r eh i rt han ０ ０１５％ and pe ghe ０ ０２％ , r e spe c t i ve l hesu l f i dei ns t e e lwa sde t e r Ｇ y, t mi neda st heTi４C２S２ ． (４) Thet r ans f o rma t i ont empe r a t ur e so fMnSt o Ti SandTi St oTi４C２S２ we r e１６２３and１２０３ K, r e Ｇ spe c t i ve l i chapp r ox ima t e l r e edwi t ht heex Ｇ y, wh yag r imen t a lr e su l t s． pe
Acknowl e dgmen t
Th i sr e s e a r c hwa ss uppo r t e dbyt heNa t i on a lNa t u r a l S c i e n c eFound a t i ono fCh i n a (Gr an tNo． ５１６０４２０１)．
６６０
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
Re f e r enc e s [１] A．Takaha sh i, T．Ha r a, H．Ogawa, I S I JI n t． ３６ (２００７) ２２９ Ｇ ２３４． [２] J．So ka, M． J é r ôme, M．So z ańska, P．Váňová, L．Ry t í r ová, j P． J onš t a, Ma t e r． Sc i．Eng．A４８０ (２００８) ２３７ Ｇ ２４３． [３] E．Mi sh i, T．Tanaka, F．Te r a s ak i, A． I keda, J．Eng． I ndus． yo ９８ (１９７６) ８８ Ｇ ８９． [４] HF． Lópe z, R． Raghuna t h, J L．Al ba r r an, L．Ma r t i ne z, Me t Ｇ a l l．Ma t e r．Tr ans．A２７ (１９９６) ３６０１ Ｇ ３６１１． [５] G．Domi z z i, G．An t e r i, J．Ov e e r o ＧGa r c í a, Co r r o s． S c i． ４３ (２００１) j ３２５ Ｇ ３３９． [６] Q． Sha, D．L i, Ma t e r． Sc i．Eng．A５８５ (２０１３) ２１４ Ｇ ２２１． [７] MT． Sheha t a, M．El bou da i n i, R W．Rev i e, Na t oSe cur．Sc i． j ６２ (２００８) １１５ Ｇ １２９． [８] J．Moon, S J．Kim, C． Le e, Me t．Ma t e r． I n t． １９ (２０１３) ４５ Ｇ ４８． [９] J F．Xu, F．Hu a ng, X．Wa ng, J． I r onS t e e lRe s． I n t． ２３ (２０１６) ７８４ Ｇ ７９１． [１０] W．Re e, A M． J o r e, O． Ba l a n c i n, S c r i t aMa t e r． ４８ (２００３) gon g p ７７３ Ｇ ７７８． [１１] E J．Sh i n, B S．Seong, YS．Han, KP．Hong, C H．Le e, l．Cr t a l l og r． ３６ (２００３) ６２４ Ｇ ６２８． HJ．Kang, J．App ys [１２] F． J i e, HJ．Wu, YC．L i u, Y．Kang, Sc i．Ch i na．Se r．E５０ (２００７) １６６ Ｇ １７６． [１３] C I．Ga r c i a, C．To rka z, C．Gr aham, AJ．De a r do, I r onmak． S t e e lmak． ３２ (２００５) ３１４ Ｇ ３１８．
[１４] Q L．Yong, MT．Ma, B R．Wu, Mi c r o a l l o e dS t e e l s—Phy s i c a l y a ndMe c h a n i c a lMe t a l l u r i n aMa ch i nePr e s s, Be i i ng, １９８９ gy, Ch j (i nCh i ne s e) ． [１５] T N． Bak e r, Y． L i, J A．Wi l s on, A J． Cr a v e n, D N． Cr owt h e r, Ma t e r． Sc i．Te chno l． ２０ (２００４) ７２０ Ｇ ７３０． [１６] Y．Kang, H．Yu, J． Fu, K．Wang, Z．Wang, Ma t e r． Sc i． Eng． A３５１ (２００３) ２６５ Ｇ ２７１． [１７] K．Oi kawa, H．Mi t su i, K． I sh i da, Ma t e r． Sc i． Fo r um５００ Ｇ ５０１ (２００５) ７１１ Ｇ ７１８． [１８] B．Pr ede l, S ＧTi (Su l f ur ＧTi t an i um), Sp r i nge r, Be r l i n He i de l Ｇ be r g, １９９８． [１９] P． Ska r ve l i s, A．Rokanopou l ou, GD．Papad imi t r i ou, Tr i bo l． I n t． ６６ (２０１３) ４４ Ｇ ４８． [２０] C J．Ba l l, Me t． Sc i． １８ (１９８４) ５７７ Ｇ ５７９． [２１] A．Bouh ema dou, R．Kh e n a t a, Phy s．Le t t．A３７２ (２００９) ６４４８ Ｇ ６４５２． [２２] J H． Swi she r, Tr ans．Me t a l l．So c．AIME． ２４２ (１９６８) ２４３３ Ｇ ２４３９． [２３] D．Al aoua, S．La r t i r e r e, L．Pr i e s t e r, Ma t e r．Sc i． gue, A．La Eng．A１８９ (１９９４) １５５ Ｇ １６３． [２４] KA．Tay l o r, Sc r i t a Me t a l．Ma t e r． ３２ (１９９４) ７ Ｇ １２． p [２５] M．Hi d no, K． I t o, The rmodynami cDa t af o rS t e e lmak i ng, ３r , TohokuUn ed． i ve r s i t e s s, Senda i, ２０１１． yPr [２６] L．Meye Lau t e r bo r n, Fe r r ousCommi t Ｇ r, F．He i s t e rkamp, D． t e eo fTMS ＧAIME, So c i e t fAu t omo t i veEng i ne e r s, Wa r Ｇ yo r enda l e, １９７３, pp． ２９３ Ｇ ３２１．
Evo l u t i ono fMnSi nc l us i onsi nTi Ｇ be a r i ngX８０p i l i nes t e e l pe Ze Ｇ anLv１ ２ , Hong Ｇwe iNi１ ２ ∗ , HuaZhang１ ２ , Cheng Ｇ songL i u１ ２ ∗ ∗ ,
, ,
,
, ,
TheS t a t eKeyLabo r a t o r fRe f r a c t o r i e sand Me t a l l u r i ve r s i t fSc i enc eandTe chno l ogy, Wuhan４３００８１, yo gy, WuhanUn yo Hube i, Ch i na ２ KeyLabo r a t o r o rFe r r ousMe t a l l u r s ou r c e sUt i l i z a t i ono fMi n i s t r fEduc a t i on, WuhanUn i ve r s i t fSc i enc eand yf gyandRe yo yo i, Ch i na Te chno l ogy, Wuhan４３００８１, Hube １
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ABSTRACT
Keywo rds: Ti t an i umＧ be a r i ngX８０ i l i nes t e e l p pe I nc l us i on Ti t an i umc a r bo su l f i de Mangane s esu l f i de Tr ans f o rma t i on Di f f us i on
S t ud i e sshowt ha tmangane s esu l f i de ( MnS) i nc l us i onsi np i l i nes t e e la f f e c tt hel a t e r a lpe r f o rmanc eo f pe s t e e li ni t sr o l l i ngde f o rma t i on, a s we l la st hehyd r ogen Ｇ i nduc edc r a ck i ngandsu l f i des t r e s sc o r r o s i on c r a ck i ngr e s i s t anc epe r f o rmanc e．Toi nh i b i tt hep r e c i i t a t i ono f MnSandi t se f f e c tonp i l i nes t e e l, a p pe i ngexpe r imen tandad i f f us i onc oup l eexpe r imen t, wh i chi nve s t i t edt heevo l u t i ono fMnSi nc l u Ｇ quench ga s i onsi nTi Ｇ be a r i ngX８０p i l i nes t e e l, we r ec onduc t ed．Theexpe r imen t a lr e su l t sshowt ha tt het r ans f o r Ｇ pe ma t i ono ft heMnSi nc l us i onsdur i ngs o l i d i f i c a t i oni sa sf o l l ows: MnS→t i t an i umsu l f i de (Ti S) →Ti ４C２S ２． Thet r ans i t i ont empe r a t ur e so fMnSt oTi SandTi St oTi r e１６７３and１２７３ K, r e spe c t i ve l y, and ４C２S ２a t heove r a l ls i z eo ft hesu l f i dede c r e a s eda swe l l．The rmodynami cc a l cu l a t i onr e su l t sc on f i rmt ha tt het r ans i Ｇ t i ont empe r a t ur e so fMnSt oTi SandTi St oTi r e１６２３and１２０３K, r e spe c t i ve l hesu l f ur y．Whent ４C２S ２a c on t en ti nt heX８０p i l i nes t e e li s０ ００１５％ , a l lt hesu l f uri nt hes t e e lc anbec onve r t edi n t oTi i t h pe ４C２S ２w at i t an i umc on t en to fmo r et han０ ０２％．
１． I n t r odu c t i on MnSi np i l i nes t e e lha sas i i f i c an timpa c ton pe gn t oughne s s, we l d i ng p r ope r t a n d s t r e s sc o r r o s i on y [１,２] c r a ck i ngpe r f o rmanc eo ft hes t e e l ．Banded MnS i nc l us i onsa f t e rr o l l i ngp r o c e s si nc r e a s et hehyd r o Ｇ Ｇ i nduc edc r a ck i ng ( HIC) andsu l f i des t r e s sc o r Ｇ gen r o s i onc r a ck i ng (SSCC) s ens i t i v i t ft he s t e e l, yo wh i chr e su l tf r om hyd r ogenen r i chmen tandc aus e mi c r oc r a cksandemb r i t t l emen t, e spe c i a l l t hc o r Ｇ ywi r o s i vega s e ssucha sH２SandCO２i nna t u r a lga s．To r educ et hee f f e c to fMnSi n c l u s i onont h ep r op e r t i e so f i e l i n es t e e l, Sc on t e n ti ns t e e ls hou l db er e du c e dt o p p (３０－５０) ×１０－６ , e v e nb e l ow１０×１０－６ ．Add i ngc a l c i Ｇ um o rr a r ee a r t hi n t o mo l t ens t e e lt o mod i f he yt mo r l ogy, s i z eand c ompo s i t i on o f MnSi nc l u Ｇ pho s i onswa spr ovedt obeano t he re f f e c t i vewayt osup Ｇ [ , ] r e s st heHICandSSCCs ens i t i v i t fs t e e l３ ４ ． p yo Pr ev i ous l l t e rna t i ves o l u t i onswe r ei n t r o Ｇ y, twoa duc edt osupp r e s st henega t i vee f f e c t so fsu l f i dei n Ｇ , achemi c l us i ons,i e． c a li nc l us i ono fshapec on t r o l (c a l c i umo rr a r ee a r t ht r e a tmen t) a ndt h ep r odu c t i on , Ph． ∗ Co r r e spond i ngau t ho r．Pr o f． D． EＧma i laddr e s s: n i hongwe i ３２０＠s ohuc ． om (HW ．Ni) ． ∗∗ Co r r e spond i ngau t ho r．Ph． D． EＧma i laddr e s s:l i uchengs ong＠wus te ．duc ． n (CS． Li u) ．
o fs t e e l s wi t he x t r a Ｇ l ow s u l f u r (b e l ow ０ ００２％) ５Ｇ７ ． [８] Moone ta l i nve s t i t edt hee f f e c t so fCaadd i t i on ga andCa/Sr a t i oon HICr e s i s t anc e．Expe r imen t a lr e Ｇ , su l t sc l e a r l r o v e dt h a tf o r m a t i o no fC a S i n s t e a d yp o fMnS, byCaadd i t i oni se f f e c t i vei nimp r ov i ngt he HICr e s i s t anc eandt h i si ss t r ong l e l a t edt ot hei n Ｇ yr c l us i onshape．HIC r e s i s t anc ei nc r e a s ed whent he Ca/Sr a t i o wa sh i rt han１ ２５andi t wa scon Ｇ ghe f i rmedt ha tt h i sva l uei sr e l a t edt ot hes t o i ch i ome t r i c [ ] r a t i obe twe enCaandS．Xue ta l ９ s t ud i edt hede s Ｇ u l f ur i z a t i onbehav i o ro fCaOＧ s a t ur a t eds l ag．Re su l t s showedt ha tde su l f ur i z a t i one f f i c i enc fCaOＧ s a t u Ｇ yo r a t eds l ag wa si n f l uenc edbyt heamoun to fr e s i dua l l i i ds l agandi t ssu l r t i onab i l i t qu phurabso p y．CaOＧ s a t ur a t eds l agha sah i rsu l i s t r i bu t i onr a t i o ghe phurd bu tal owe rappa r en tr a t econs t an tt hanl i i ds l ag qu i nt hede su l f ur i z a t i onr e a c t i on．Whent hes l a ompo Ｇ gc s i t i on wa s６２ ５％ CaOＧ ２２ ５％ Al２O３Ｇ ５％S iO２Ｇ １０％ CaF２ , t hed e s u l r i z a t i onr a t i owa sh i rt han８８％ phu ghe andt hec on t e n to fs u l h u rw a s l o w e rt h a n１ ０×１ ０－６ , p wh i chr educ e st heimpa c to fsu l f i de sont he HIC , r f o rmanc eo fp i l i nes t e e l．Howeve r p r ev i ous pe pe [
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Re c e i ved１２Sep t embe r２０１６; Re c e i vedi nr ev i s edf o rm３０Novembe r２０１６; Ac c ep t ed２De c embe r２０１６ Ava i l ab l eon l i ne１５June２０１７ / , , １００６ Ｇ ７０６X Copy r i tⓒ２０１７ Th ee d i t o r i a lo f f i c eo fJ ou r n a lo fI r ona ndS t e e lRe s e a r c hI n t e r n a t i on a l． Pub l i s h e dbyE l s e v i e rL imi t e d．Al lr i t sr e s e r v e d． gh gh
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
wo rkswe r ema i n l o cus edon MnS mod i f i c a t i onby yf c a l c i umt r e a tmen to rr educ t i ono fSc on t en ti nt he s t e e l, andf ews t ud i e shavebe enc a r r i edou tont he t r ans f o rma t i on o f MnS by Tit r e a tmen t, wh i ch c ou l di nh i b i tt henega t i vee f f e c to fMnSandimp r ove t hequa l i t fp i l i nes t e e l． yo pe Theso l i ds o l u t i onands eg r ega t i ono fTi Ｇ be a r i ng i nc l us i onsi nTia l l oys t e e l sc anr e t a r daus t en i t er e Ｇ , c r s t a l l i z a t i o na n d r a i n r o w t h． I nt h i sw a af i n e y g g y r a i n mi c r o s t ruc t u r ec ou l d bea ch i evedt oenhanc e g [ , ] t hes t e e ls t r eng t h１０ １１ ．Thef o rma t i ono ft i t an i um c a rbosu l f i de (Ti４C２S２ ) p r e c i i t a t e s, wh i chc ani n Ｇ p h i b i t MnS pr e c i i t a t i on and s i i f i c an t l r ove p gn y imp t heHICandSSCCr e s i s t anc eo fp i l i nes t e e l s, i s pe ano t he rimpo r t an tr o l et ha tt he mi c r oa l l oy i ng e l e Ｇ men tTip l aysi np i l i nes t e e l s． I nt h i ss t udy,t oi n Ｇ pe h i b i tt he pr e c i i t a t i ono f MnSandi t sun f avo r ab l e p e f f e c tonp i l i nes t e e l, r e s e a r chont heevo l u t i ono f pe MnSi nc l us i onsi nTi Ｇ be a r i ngX８０p i l i nes t e e lwa s pe c onduc t ed． Change si nt hemo r l ogyandc ompo s i Ｇ pho t i ono ft hei nc l us i onsi nt he X８０ s t e e l we r eana Ｇ l z ed, andt het r ans f o rma t i on p r o c e s sand me cha Ｇ y n i smo fMnSt oTi４C２S２c onv e r s i oni nT i Ｇ b e a r i ngX８０ i e l i n es t e e lwa sa l s oi nv e s t i a t e da ndd i s c u s s e d, a l ong p p g wi t ht heo r e t i c a lt he rmodynami cana l s i s ． y
２．Exp e r imen t a l ２ １． Quench i ngexpe r imen t Fo racomp l e t et r ans f o rma t i ono fMnSt oTi４C２S２ i ns t e e l, t hecon t en to ft i t an i um wa ss e l e c t ed a s [ ] ０ ０３wt ％ wh i l et ha to fSwa s０ ００１５wt ％ １２Ｇ１６ ． Us i ngava cuumi nduc t i onf urna c e, Ti Ｇbe a r i ng X８０ ( ) i l i nes t e e li ngo t １０kg wa sp r epa r ed; t hef i na l p pe compos i t i ona swe l la st heAme r i c anPe t r o l eumI n Ｇ s t i t u t es t anda rdso fX８０ p i t e e l (APISpe c５L, pes , ) ５ t h ２０１２ a r el i s t edi nTab l e１． F i vei n i t i a ls amp l e s (１kgf o re a chone) we r et akenf r omt hei ngo tand r e Ｇme l t edi nana l umi nac ruc i b l ei na mo l ybdenum d i s i l i c i def urna c eunde ra r r o t e c t i on．Af t e rad Ｇ gonp us t i ngt he ma i ns t e e lcompos i t i onsa t１８７３ Kf o r j ０ ５h,i n i t i a ls amp l e swe r ewa t e rquencheda t１８７３, １６７３, １４７３, １２７３, and１０７３K, r e s e c t i v e l i １)． p y (F g Thr e eme t a l l og r aph i cspe c imens(１０mm×１０mm× １０ mm) we r et akenf r ome a chi n i t i a ls amp l ef o ran a l Ｇ s i s, a tpos i t i onsi nd i c a t edi nF i ２．Thef i na lcomＧ y g i t i onso fX８０p i l i nes t e e li ngo twe r eme a sur ed pos pe byi nduc t i ve l c o u l e d l a s m ae m i s s i o ns e c t r o m e Ｇ y p p p ( ) , , t r I C P Ｇ A E S ． T h em o r h o l o s i z e n u m b e r a n d y p gy chemi c a lcompos i t i ono fi nc l us i onsi nt heme t a l l og r Ｇ
Tab l e１ Chemi c a lc ompo s i t i onso fexpe r imen t a lX８０s t e e landAPIs t anda r ds (wt ％ ) I t em
C
S i
Mn
S
P
Ti
N
Expe r imen t a ls t e e l ０ ０２６ ０ ２８ １ ６ ０ ００１６ ０ ００１５ ０ ０３２ ０ ００２０ ) APISpe c５L (max． ０ １２ ０ ４５ １ ８５ ０ ０１ ０ ０２ ０ ０６ － No t e: a—Ni＋V＋Ti≤０ １５％ ; b—Cu≤０ ５％ , Ni≤０ ５％ , Cr≤０ ５％ , Mo≤０ ５％ , B≤０ ０００５％．
F i １． Tempe r a t u r ecu r veo fme l t i ngandquench i ngf o r g s t e e ls amp l e s．
６５５
TO
０ ００６２ －
Ot he r － a, b
F i ２． Samp l i ngpo s i t i onso fi n i t i a ls amp l e s． g
i nes t e e l(５００g) andMnS (５０g) we r ep l a c edi n t oan a l umi na c ruc i b l ei nah i Ｇ t empe r a t ur er e s i s t anc e gh aph i cspe c imenswe r eme a su r edbys c ann i nge l e c t r on f urna c eunde ra r r o t e c t i on．Thes amp l e s we r e gon p mi c r os copy (SEM) andene r i spe r s i vespe c t r ome Ｇ f gyd i r s the a t eda t１８７３Kf o r１h, andt hencoo l eddown t r y (EDS) ． t o１４７３Ki nf urna c e, andf i na l l t e r． yquenchedbywa S c h e m a t i co f t h ed i f f u s i o nc o u l ee x e r i m e n t i ss h o w n p p ２ ２．Diffu s i onc oupl eexpe r imen t i nF i ３．Av e r t i c a lc r o s s Ｇ s e c t i ono ft hequ e n c he ds amp l e g Toc l a r i f heevo l u t i onp r o c e s sandme chan i smo f wa yt s mi r r o r Ｇ l i shed wi t hS iCＧ coa t eds andpape rand po MnS→ Ti S→ Ti４C２S２ t r ans i t i oni nT i Ｇ b e a r i ng X８０ d i amondpa s t e．The mo r l ogyandchemi c a lcomＧ pho i e l i n es t e e l, ah e a tt r e a tme n te xp e r ime n twa sd e s i e d pos p p gn i t i onso ft he MnSl aye rand X８０s t e e lsubs t r a t e a ndc a r r i e dou tbyd i f f us i onc oup l eme t hod．X８０p i l Ｇ we pe r ea l some a sur edandana l z edbySEMＧEDS． y
６５６
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
F i ３． Schema t i co fd i f f us i onc oup l eexpe r imen tf o rTi Ｇbe a r Ｇ g i ngX８０p i l i nes t e e l． pe
３．Re s u l t s
３ １．Change si n mo rpho l ogy andc ompo s i t i onof i nc l u s i on si nX８０s t e e l
t e e ls amp l e swe r eana l z edbyus i ngnon Ｇ quencheds y me t a l l i ci nc l us i onau t oma t i cana l i sso f twa r e (ImＧ ys age Ｇ r oP l us), a sshowni nF i ５．Dur i ngso l i d i f i c a Ｇ p g t i on, su l f i dei nc l us i onsma i n l i s t edo fMnSand ycons Ti Sf r om１８７３t o１６７３K． Pe r c e n t a e so fMnSandTi S g de c r e a s edandi nc r e a s edr e spe c t i ve l t ht het emＧ y wi r a t ur ede c r e a s i ngf r om１６７３t o１４７３K, wh i chi n Ｇ pe d i c a t edt ha tpa r to ft he MnSt r ans f o rmedi n t o Ti S． Asso l i d i f i c a t i oncon t i nued, Ti４C２S２ begant opr e c i pＧ i t a t ewhent hequench i ngt empe r a t ur ede c r e a s edt o １４７３K．Ast hequench i ngt empe r a t ur ede c r e a s edt o １２７３ K, bo t ho ft hepe r c en t age so fMnSandTi Sde Ｇ c r e a s edf ur t he r, whe r e a st ha to f Ti４C２S２ i nc l us i on i nc r e a s eds i i f i c an t l r eove r, t hepe r c en t ageo f gn y．Mo Ti４C２S２i nc r e a s edt o６２％ andt ha to fMnSde c r e a s ed t o２４％ whent hequ e n c h i ngt emp e r a t u r ewa s１０７３K．
Thenumbe r so fsu l f i de si n５０f i e l dso fv i ewa td i f Ｇ f e r en tquench i ngt empe r a t u r e sa r el i s t edi nTab l e２． Wi t hd e c r e a s i ngt h equ e n c h i ngt emp e r a t u r e, t h eamoun t , o fs u l f i d e si nc r e a s edg r adua l l spe c i a l l r i ngt emＧ ye ydu r a t ur ef r om １８７３t o１６７３ K．Thepe r c en t age so f pe d i f f e r en t Ｇ s i z ed su l f i dei nc l us i onsi nt he s t e e la f t e r i ng a td i f f e r en tt empe r a t u r e sa r e showni n quench F i ４．Ast hes o l i d i f i c a t i on p r o c e s sp r o c e eded, t he g su l f i de i nc l us i on s i z e de c r e a s ed g r adua l l t e r y．Af i nga t１８７３K, mo r et han７０％ o ft hesu l f i de s quench we r el a r rt han５μm, andapp r ox ima t e l ft he ge y２％ o su l f i dei nc l us i onswe r esma l l e rt han２μm; whent he i ngt empe r a t u r ede c r e a s edt o１０７３ K, ne a r l quench y Fi ５． T e sa ndr a t i o so fs u l f i d e si ns t e e la f t e rquench i nga t yp g ７０％ o ft hei nc l us i onswe r esma l l e rt han２μm． d i f f e r en tt empe r a t u r e s． Thenumbe ra ndr a t i oo ft h es u l f i d ei n c l u s i on si nt h e Mo r l ogyo ft i c a li n c l u s i on si ss howni nF i ６． pho yp g Tab l e２ Thema o rs u l f i d ei n c l u s i on sa t１８７３Ka r es i ng l es r i Ｇ j phe Numb e ro fs u l f i d e si n５０f i e l d so fv i ewa td i f f e r en tquench i ng c a lMnS pa r t i c l e so f５－１０ μm; when quencheda t t empe r a t u r e s １６７３K, t hema o rsu l f i de sa r e ( Mn,Ti)S, andt he j Tempe r a t ur e/K １８７３ １６７３ １４７３ １２７３ １０７３ c ompoundi n c l u s i oni ss u r r ound e dbyanou t e r(Al,T i)O Numbe ro fsu l f i de s １３ ４７ ５９ ６８ ８５ l a e r．Thes i z eo f( Mn,Ti)Sando t he rcompoundi n Ｇ y c l us i onsi s３－５ μm．Wi t ht hequench i ngt empe r a Ｇ t ur ede c r e a s i ngt o１４７３ K, t he ma o ri nc l us i oni sa j compoundi n c l u s i onwi t h ( Mn,T i)Sa sc o r e, s u r r oun Ｇ ( , ) , d e dby Al S i O．Af t e rquench i nga t１２７３ K su l Ｇ f i de schangedi n t oT i u r r ound e dby ( Mn,T i)S, ４C ２S ２s whe r e a st hes i z ede c r e a s edt oabou t２ μm． I nadd i Ｇ t i on, mo r esma l l Ｇ r t i c l eTi４C２S２ p r e c i i t a t ed when pa p i nga t１０７３ K．Al ong wi t hso l i d i f i c a t i on, i t quench wa si n f e r r edt ha tt het r ans f o rma t i on pa t ho f MnS wa sMnS→Ti S→Ti４C２S２ , andt ha tt hesu l f i des i z e de c r e a s eds i i f i c an t l gn y．
３ ２．Ob s e rva t i on sa ti n t e r ac eb e twe en MnS and f s t e e lbydi u s i onc oupl eexpe r imen t f f
F i ４． Su l f i des i z ed i s t r i bu t i ona td i f f e r en tt empe r a t u r e s g du r i ngc oo l i ngp r o c e s s．
F i ７showst hee l emen tl i nes c ann i ngr e su l t sa t g t hei nt e r f a c ebe twe en MnSandX８０s t e e lma t r i x． I t
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
６５７
(a) １８７３K; (b) １６７３K; (c) １４７３K; (d) １２７３K; (e) １０７３K．
F i ６． Mo r l ogyo ft i c a li nc l us i onsi ns t e e la f t e rquench i nga td i f f e r en tt empe r a t u r e s． pho yp g
F i ７． El emen tl i nes c animageo fMnS Ｇ subs t r a t etwo Ｇpha s ei n t e r f a c e． g
i nd i c a t edac l e a ri n t e r f a c e, andamu t ua lpene t r a t i on i sa l soobs e r vedbe twe en MnSands t e e l．Thepene Ｇ t r a t i on Ｇ l aye rt h i ckne s si s abou t １５０ μm．Re su l t s showedt ha tt hec on t en t so fMnandSde c r e a s eds i Ｇ g n i f i c an t l nt he MnS Ｇ t o Ｇ s t e e lsubs t r a t ed i r e c t i on． yi Thecon t en t so fTia l s oshowedade c r e a s i ngt r end f r om t he X８０ s t e e l ma t r i xt ot he MnS d i r e c t i on, wh i chi nd i c a t edt ha tTii nt hes t e e ld i f f us edt ot he MnSs i de．Thec on t en to fTii n MnSne a rt he MnS Ｇ s t e e li n t e r f a c ei nc r e a s edt oabou t０ ００１５％． F i ８i l Ｇ g l us t r a t e st heSEM mi c r og r apho fsu l f i de sne a rand f a rf r om t hei n t e r f a c ebe twe en MnSand X８０sub Ｇ s t r a t e．Compo s i t i onso ft hei nc l us i onsa r eshowni n Tab l e３．Re su l t sshowedt ha ti nt heX８０s t e e lsub Ｇ s t r a t e, Ti４C２S２ o rab i na r l f i deo f MnS ＧTi４C２S２ ysu r e c i i t a t edne a rt hei n t e r f a c ebe twe ent he MnSand p p X８０p i l i nes t e e l, and MnSi nc l us i onsmo s t l i s Ｇ pe yex t edawayf r omt hei n t e r f a c e．
４．Di s c u s s i on ４ １．Crys t a ls t ruc t ur et ran s o rma t i on mode l of f MnSt oTi４C２S２ Pr ev i ouss t ud i e sont het he rmodynami ca s s e s s Ｇ men to ft heFe ＧMn ＧTi ＧCＧSs s t e ms h o w e d t h a tw h e n y t hewe i tr a t i oo fS/Tiwa sl e s st han２, Ti S wa s gh [ ] expe c t edt op r e c i i t a t ep r i o rt o MnS１７ ．Dur i ngt he p r ima r t ageo fso l i d i f i c a t i on, MnSt r ans f o rmedi n Ｇ p ys t oTi Sbyt he mu t ua ld i f f us i ono f Mnand Ti．EDS r e su l t swe r esuppo r t edbye l e c t r onba ck Ｇ s c a t t e rd i f Ｇ f r a c t i on (EBSD) da t a, andi ti nd i c a t edt ha tt heTi S f o l l owsa NiAs Ｇ t r t a lun i tc e l l (spa c eg r oup ypec ys P６３ /mmc) wi t hl a t t i c epa r ame t e r so fa＝０ ３２９nm [ ] andc＝０ ６３９nm １８ ．TwoTia t omsex i s ti nt he (０, ０, ０) pos i t i onsandano t he rtwoSa t omsi nt he (２/３, １/３, １/４) pos i t i ons．Tia t omsa r ec ent e r edi nad i Ｇ
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
６５８
(a) Ne a ri n t e r f a c e (２０μm); (b) Fa rf r omi n t e r f a c e (５００μm) ．
F i ８． SEM mi c r og r apho fsu l f i de sne a randf a rf r omi n t e r f a c ebe twe en MnSandX８０s t e e l． g Tab l e３ EDSana l s i sr e su l t si nF i ８ (ma s s％ ) y g Po s i t i on
Ti S
Ti ４C２S ２
Al２O３
S iO２
－
１１ ７
８２ ６
５ ４
０ ３
－
５ ６
８８ ７
５ ２
０ ５
１１ ８
－
７ ５
２ ７
MnS
１
７４ ６
３
６４ ９
５
９０ ４
７
８２ ７
２ ４ ６
７８ ０
１２ ４ １８ ５ ３ ８ ８ ５
－ －
－ －
８ ２
１０ １ ４ ６ ７ ９
new T i n i tc e l li sf o rme dbyt heCa t omi nT i C ４C ２S ２u r ep l a c i ngf ourva c anc i e si nTi S, a sshowni nF i ９． g
４ ８
６ ５ １ ２ ０ ９
s t o r t edoc t ahed r onf o rmedbys i xSa t omsandt he su l f uri ons haveat r i o n a lc o o r d i n a t i o n w i t h t he g t r ans i t i on me t a l．The S a t omsf o rm c l os e Ｇ a c k e d p l aye r st ha ta r ea r r angedi nahexagona ls t a ck i ngs e Ｇ [１９] e ． quenc Ti４C２S２i sat he rmodynami c a l l t ab l ec ompound ys t ha tappe a r seveni nu l t r a Ｇ l ow c a rbons t e e l s．EBSD ana l i sshowst ha tTi４C２S２ ha sahexagona lc r t a l ys ys s t ruc t ur ewi t hl a t t i c epa r ame t e r so fa＝０ ３２nmand c＝１ １２nm．Thel a t t i c epa r ame t e r so fTi４C２S２ ob Ｇ t a i ned by EBSD ag r e e wi t ht ho s e ob t a i ned by [ ] Ba l l２０ ．Ti４C２S２c r t a l l i z e sa c c o r d i ngt ot heCr２AlC ys r o t o t c eg r oup P６３ /mmc) ．Ca rbona t oms p ype (spa o c cupyt hepo s i t i ono f (０, ０, ０) and (０, ０, １/２), su l f ura t omso c cupyt hepo s i t i ono f(１/３, ２/３, ３/４) and (２/３, １/３, １/４), andt i t an i um a t omso c cupy t hepos i t i ono f(１/３, ２/３, z), (２/３, １/３, z＋１/２), (２/３, １/３, －z) and (１/３, ２/３, －z＋１/２), whe r e [ ] z equa l st o０ ０９９８２１ ． TiC p r e c i i t a t edi nc a rbon Ｇ r i cha r e a sdu r i ngt he p l a t eso l i d i f i c a t i on．TheTi Cc r s t a l i sac u b i cc r s t l y ya , s s t e m w i t ha s a c e r o u o fF m Ｇ ３ m w h i c hb e l o n s y p g p g t o a sod i um ch l o r i de Ｇ t r t a ls t ruc t u r e．Ti S ype c ys t r ans f o rmedi n t o Ti４C２S２ byi s omo r t i t u Ｇ phoussubs t i on．Be c aus eTi SandTi４C２S２ haveas imi l a rc r t a l ys s t ruc t ur e, a t omo c cupa t i onandl a t t i c epa r ame t e r, a
Fg ９． Fo rma t i ono fTi n i tc e l lf r om Ti SandTi C． ４C ２S ２u
４ ２．The rmodynami c ana l i sof t i t an i um i nc l u Ｇ ys s i on si nTi Ｇ b ear i ng X８０pipe l i nes t e e l
Theso l ub i l i t t ao fTiC, TiN, MnS, Ti Sand yda Ti４C２S２f r omso l u t eTi, Mn, S, andCi nt heFe ＧCＧ [ ] S ＧMn ＧTia l l oysys t ema r er e r e s e n t e di nT ab l e４２２Ｇ２５ , p andt hee s t ima t edt empe r a t ur e dependenc eo ft he so l ub i l i t r oduc t sf o r TiC, TiN, MnS, Ti S and yp Ti４C２S２i sp l o t t edi nF i １０．Theso l ub i l i t oduc t s g ypr o ft he s e compoundsf o l l ow t he o rde ra s TiN ＜ TiC０５S０５ ＜ Ti S＜ MnS＜ TiC be l ow １２４５ K．The t r ans i t i ont empe r a t ur e so f MnSt o Ti Sand Ti St o Ti４C２S２a r e１５５０and１２４５K,r e s e c t i v e l Th i sa r e e s p y． g wi t ht he p r e c i i t a t i on s equenc eo fsu l f i de si n Ti Ｇ p [ ] be a r i ngs t e e l s２６ ． I so t he rma ls e c t i onso fs u l f i d ep r e c i i t a t e sa t１４７３K p i nt heFe Ｇ ０ ００２５CＧ ０ ００３NＧ １ ５Mn ＧS ＧTis t em a r e ys showni nF i １ １． T h ec a l c u l a t e dr e s u l t sa r e e w e l l g g wi t ht heobs e r vedp r e c i i t a t e t e s ． Wh e n t h e s u l f u r p yp cont enti nX８０p i l i nes t e e lwa s００１５％ , a l lsu l Ｇ pe
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
Tab l e４ Func t i ono fp r e c i i t a t e ss o l ub i l i t ns t e e l p yi Compound TiN
MnS
Pha s e
L i i d qu γ
α, δ
L i i d qu
So l ub i l i t oduc t ypr
l ogK TiN ＝l ogw [Ti]w [N] ＝ －１４０００/T ＋４ ７ l ogK TiN ＝l ogw [Ti]w [N] ＝ －１３８６０/T ＋３ ７５ l ogK TiN ＝l ogw [Ti]w [N] ＝ －１６６５０/T ＋４ ８ ogw [ Mn]w [S] ＝ －６０５０/T ＋３ ４ l ogK MnS＝l
α, δ
l ogK MnS＝l １ ogw [ Mn]w [S] ＝ －１１２００/T ＋５ l ogK MnS＝l ogw [ Mn]w [S] ＝ －１２０００/T ＋４ ９
γ
Ti S
L i i d qu γ
l ogK TiS＝l ogw [Ti]w [S] ＝ －１６５５０/T ＋６ ７５
Ti ４C２S２
L i i d qu α, δ
－ l ogK TiC０５S０５ ＝l ogw [Ti]w [C]０５w [S]０５＝ －１５３１０/T ＋６ ０３ －
γ
l ogK TiC ＝l ogw [Ti]w [C] ＝ －７０００/T ＋２ ７５
Ti C
α, δ γ
L i i d qu α, δ
－
－
－
l ogK TiC ＝l ogw [Ti]w [C] ＝ －９５７５/T ＋４ ４
F i １０． Tempe r a t u r edependenc eo fs o l ub i l i t r oduc t sf o r yp g Ti S, Ti C０５S０５ , TiN, Ti C, and MnS．
F i １１． Ca l cu l a t edpha s ed i ag r amo fsu l f i dep r e c i i t a t e sa t p g １４７３Ki nFe Ｇ ０ ００２５CＧ ０ ００３NＧ １ ５Mn ＧS ＧTisy s t em us i ng s o l ub i l i t r oduc t s． yp
f i de si nt hes t e e lc ou l d bec onve r t edi n t o Ti４C２S２ wi t hat i t an i umc on t en to fmo r et han０ ０２％．Wi t h t hei nc r e a s ei nsu l f u randt i t an i um c on t en t si n X８０ i l i nes t e e l, t hesu l f i dei ns t e e lwa sde t e rmi neda s p pe
６５９
Ti４C２S２ ． Fa c t Sa ec a l c u l a t i onr e s u l t sf o rsu l f i dep r e c i i t a t e s g p i nTi Ｇbe a r i ngX８０p i l i nes t e e la r eshowni nF i １２． pe g Duet ot hes t r ong a f f i n i t f Tiand N, TiN and yo MnSp r e c i i t a t eddur i ngt hee a r l t ageo fso l i d i f i c a Ｇ p ys t i oni nTi Ｇbe a r i ngX８０p i l i nes t e e l．Ast het empe r Ｇ pe a t ur ede c r e a s edt o１６２３and１２０３ K, pa r to f MnS i nc l us i onschangedt oTi Sandt hent oTi４C２S２ , r e Ｇ spe c t i ve l ． T h em a x i m u m r e c i i t a t i o n u a n t i t a n d y p p q y r e c i i t a t i ont imef o r MnSand Ti４C２S２ dependon p p t hesu l f urandn i t r ogencon t en t si nt hes t e e l．Ti Sand Ti４C２S２ begant op r e c i i t a t eon l f t e rt hef o rma t i on p ya o fTiN．Thet r ans f o rma t i ont empe r a t ur e so fMnSt o Ti SandTi St oTi４C２S２ we r e１６２３and１２０３ K, r e Ｇ spe c t i ve l i chapp r ox ima t e l r e edwi t ht heex Ｇ y, wh yag r imen t a lr e su l t s． pe
F i １２． Ca l cu l a t edma s sf r a c t i ono fsu l f i dep r e c i i t a t e si n p g Ti Ｇbe a r i ngX８０p i l i nes t e e l． pe
５．Conc l u s i on s (１) Ast het empe r a t ur ede c r e a s e sf r om １８７３ K t o１０７３ K dur i ngso l i d i f i c a t i on, su l f i de si nt heX８０ : s t e e lchangeda l ongt hepa t h MnS→Ti S→Ti４C２S２ andt hes i z eo fsu l f i de sde c r e a s edg r adua l l y． (２) Ti SandTi４C２S２ haveas imi l a rc r t a ls t ruc Ｇ ys t ur eanda t om oc cupa t i on, wh i ch, i nt heo r Ｇ y, con t r i bu t edt ot het r ans f o rma t i ono fTi Si n t o Ti４C２S２ byi somo r t i t u t i on． phoussubs (３) Whent hesu l f urandt i t an i umcon t en t si nt he X８０ p i l i nes t e e l we r eh i rt han ０ ０１５％ and pe ghe ０ ０２％ , r e spe c t i ve l hesu l f i dei ns t e e lwa sde t e r Ｇ y, t mi neda st heTi４C２S２ ． (４) Thet r ans f o rma t i ont empe r a t ur e so fMnSt o Ti SandTi St oTi４C２S２ we r e１６２３and１２０３ K, r e Ｇ spe c t i ve l i chapp r ox ima t e l r e edwi t ht heex Ｇ y, wh yag r imen t a lr e su l t s． pe
Acknowl e dgmen t
Th i sr e s e a r c hwa ss uppo r t e dbyt heNa t i on a lNa t u r a l S c i e n c eFound a t i ono fCh i n a (Gr an tNo． ５１６０４２０１)．
６６０
Z A ． Lve ta l．/Journa lofI r onandSt e e lRe s ear ch, In t e rna t i ona l２４ (２０１７) ６５４－６６０
Re f e r enc e s [１] A．Takaha sh i, T．Ha r a, H．Ogawa, I S I JI n t． ３６ (２００７) ２２９ Ｇ ２３４． [２] J．So ka, M． J é r ôme, M．So z ańska, P．Váňová, L．Ry t í r ová, j P． J onš t a, Ma t e r． Sc i．Eng．A４８０ (２００８) ２３７ Ｇ ２４３． [３] E．Mi sh i, T．Tanaka, F．Te r a s ak i, A． I keda, J．Eng． I ndus． yo ９８ (１９７６) ８８ Ｇ ８９． [４] HF． Lópe z, R． Raghuna t h, J L．Al ba r r an, L．Ma r t i ne z, Me t Ｇ a l l．Ma t e r．Tr ans．A２７ (１９９６) ３６０１ Ｇ ３６１１． [５] G．Domi z z i, G．An t e r i, J．Ov e e r o ＧGa r c í a, Co r r o s． S c i． ４３ (２００１) j ３２５ Ｇ ３３９． [６] Q． Sha, D．L i, Ma t e r． Sc i．Eng．A５８５ (２０１３) ２１４ Ｇ ２２１． [７] MT． Sheha t a, M．El bou da i n i, R W．Rev i e, Na t oSe cur．Sc i． j ６２ (２００８) １１５ Ｇ １２９． [８] J．Moon, S J．Kim, C． Le e, Me t．Ma t e r． I n t． １９ (２０１３) ４５ Ｇ ４８． [９] J F．Xu, F．Hu a ng, X．Wa ng, J． I r onS t e e lRe s． I n t． ２３ (２０１６) ７８４ Ｇ ７９１． [１０] W．Re e, A M． J o r e, O． Ba l a n c i n, S c r i t aMa t e r． ４８ (２００３) gon g p ７７３ Ｇ ７７８． [１１] E J．Sh i n, B S．Seong, YS．Han, KP．Hong, C H．Le e, l．Cr t a l l og r． ３６ (２００３) ６２４ Ｇ ６２８． HJ．Kang, J．App ys [１２] F． J i e, HJ．Wu, YC．L i u, Y．Kang, Sc i．Ch i na．Se r．E５０ (２００７) １６６ Ｇ １７６． [１３] C I．Ga r c i a, C．To rka z, C．Gr aham, AJ．De a r do, I r onmak． S t e e lmak． ３２ (２００５) ３１４ Ｇ ３１８．
[１４] Q L．Yong, MT．Ma, B R．Wu, Mi c r o a l l o e dS t e e l s—Phy s i c a l y a ndMe c h a n i c a lMe t a l l u r i n aMa ch i nePr e s s, Be i i ng, １９８９ gy, Ch j (i nCh i ne s e) ． [１５] T N． Bak e r, Y． L i, J A．Wi l s on, A J． Cr a v e n, D N． Cr owt h e r, Ma t e r． Sc i．Te chno l． ２０ (２００４) ７２０ Ｇ ７３０． [１６] Y．Kang, H．Yu, J． Fu, K．Wang, Z．Wang, Ma t e r． Sc i． Eng． A３５１ (２００３) ２６５ Ｇ ２７１． [１７] K．Oi kawa, H．Mi t su i, K． I sh i da, Ma t e r． Sc i． Fo r um５００ Ｇ ５０１ (２００５) ７１１ Ｇ ７１８． [１８] B．Pr ede l, S ＧTi (Su l f ur ＧTi t an i um), Sp r i nge r, Be r l i n He i de l Ｇ be r g, １９９８． [１９] P． Ska r ve l i s, A．Rokanopou l ou, GD．Papad imi t r i ou, Tr i bo l． I n t． ６６ (２０１３) ４４ Ｇ ４８． [２０] C J．Ba l l, Me t． Sc i． １８ (１９８４) ５７７ Ｇ ５７９． [２１] A．Bouh ema dou, R．Kh e n a t a, Phy s．Le t t．A３７２ (２００９) ６４４８ Ｇ ６４５２． [２２] J H． Swi she r, Tr ans．Me t a l l．So c．AIME． ２４２ (１９６８) ２４３３ Ｇ ２４３９． [２３] D．Al aoua, S．La r t i r e r e, L．Pr i e s t e r, Ma t e r．Sc i． gue, A．La Eng．A１８９ (１９９４) １５５ Ｇ １６３． [２４] KA．Tay l o r, Sc r i t a Me t a l．Ma t e r． ３２ (１９９４) ７ Ｇ １２． p [２５] M．Hi d no, K． I t o, The rmodynami cDa t af o rS t e e lmak i ng, ３r , TohokuUn ed． i ve r s i t e s s, Senda i, ２０１１． yPr [２６] L．Meye Lau t e r bo r n, Fe r r ousCommi t Ｇ r, F．He i s t e rkamp, D． t e eo fTMS ＧAIME, So c i e t fAu t omo t i veEng i ne e r s, Wa r Ｇ yo r enda l e, １９７３, pp． ２９３ Ｇ ３２１．