TOM TAT Dd sd diing phdn mem DEFORMTM 2D vdi thuat todn phdn td hdu han Finite Element Meth-od, FEM de mo phong sd 2D qud trinh ep dim hen ttic bdng ma sdt trong kenh gdp khuc tiet die
Trang 1NGHIEN Cflu - TRAO D 6 | PHAN TiCH BANG PHLCONG PHAP PHAN TLC H & U HAN (FEM) A N H HU-dNG CLIA TRANG THAI LfNG S U A T B i N QUA T R I N H BlfeN DANG TRONG KY THUAT
EP DUN LIEN TUC BANG MA SAT QUA KENH GAP KHUC CO TI^T DIEN KHONG B 6 |
FINITE ELEMENT ANALYSIS OF STRESS EFFECT ON DEFORIVIATION IN CONTINUOUS
FRICTIONAL ANGULAR EXTRUSION (CFAE) PROCESS
Pham Quang', Nguyen Thi Hoang Canh', D i o Minh Ngirng', Nguyen Dang Khoa^
'Vien Khoa hgc va Ky thuat Vat lieu, TrUdng Dai hoc Bach khoa Ha Ndi
'Khoa Cdng nghe Vat lieu, Trudng Dai hoc Bich khoa - Dai hgc Qudc gia Thinh phd Hd Chi Minh
TOM TAT
Dd sd diing phdn mem DEFORMTM 2D vdi thuat todn phdn td hdu han (Finite Element
Meth-od, FEM) de mo phong sd 2D qud trinh ep dim hen ttic bdng ma sdt trong kenh gdp khuc tiet dien khong doi (Continuous Frictional Angular Extrusion, CFAE) nham tao cdu true sieu min cho vat lieu nhd hinh
;i hi Ti-Ni Phdn tich ket qud tinh todn dng sudt keo-nen theo chieu XvdY tdc dong len cdc phdn td khi di j qua goc kenh cho phep gidi thich cOchetrUOt vdxoay trong qua trinh bien dang deo ddn tdi cdu truchqt
^ gid tiidng bi keo ddi tdi 65% vd bi nen lai tdi 43% Qua do cung ldm sdng to st^phdn bovd bi^n thien bien dang tren cdc phdn cua mdu trong ky thuat CFAE
ABTRACT
_ The DEFORMTM 2D commercial software package using finite element method (FEM) to simu-late the continuous frictional angular pressing (CFAE) process was applied for bulk ultra-fine grained , (UFG) Nitinol alloy system (Ti-Ni) The sliding and rotation mechanisms of the plastic deformation lead-ing to a 65% elongation and a 43% shrinkage of simulated grains were explained by analyzlead-ing calculated tensile and compression stresses acting on Nitinol workpiece in X and Y directions Thus the deformation distribution and evolution in CFAE-ed workpiece parts were also clarified
Keywords: SPD, ECAP CFAE, FEM, UFG, Nitinol, Tini
1 GlOl THIEU CHUNG true hinh thanh thudng cd dang hat Idn, phan Idn
l i bien hat djnh hudng gdc nhd, trong khi phuong , PhilOng p h i p bien dang deo m i n h Uet phip SPD cd can true dang hjt min vdi bien hat (Severe Plastic Deformation, SPD) l i qua trinh gdc Idn Cau true cua vat heu nhan duoc sau q u i e! t}o hinh kun loai vdi mdc do bien dang Idn, i p ItJc trinh SPD cd dac diem nhU: i) kich thitdc tinh the dat Ien miu djng khdi d i n den thay doi cau true cua hat giam den cap dd nand; ii) mat do lech tU S' vi md trong toin bd the tich cua mau d nhiet dd do thap; iii) cac hat cd dinh hudng gdc Idn, nang thap vi lam nhd min hat trong q u i trinh gia cdng lUOng v i tr?ng thii m i t cin bang cua bien hat cao
Cac ky thuit bien dang manh nhu can v i keo cd [2] Cau triic nay dan den ting dang ki do ben, do
thf lam min hat d nhiet do thap [ 1 ], tuy nhien cau deo, do ehdng m i i mdn v i tdc do bien dang deo
Trang 2Mdt trong eic phfldng phap SPD thdng
dung nhat la ky thuat Ip trong k i n h gap khue tiet
di?n khdng ddi (Equal Channel Angular
Press-ing, ECAP) 13] Ky thuat niy dUa vio nguyen ly
biln dang trUpt nhieu lan dan ldi kich thUdc hat
trong khdi kim loai giam Qua trinh ep lap di lap
lai nhieu lan gay ra bien dang deo Idn eua mau
lim i n h hUdng ldi d i e dicm eau true vi md cua
vit li^u Khi dd cau true vi md eua mau hinh
thanb cie hat dang hUdng vdi kich thfldc dfldi
micrdmet Trong q u i trinh ECAP, mau dflpe quay
90 o hoac 180 o tuy theo Ip trinh ep A, B hay C
gifla mdi lan Ip Cau true dii hinh t h i n h trong lan
ep trflde dd se tao ra thinh cie hat ed kich tbflde
nhd hpn de tao thinh eic hat sieu min Qua trinh
ehe tao tfldng ddi ddn gian va hi|u q u i vdi nhieu
loai vat li?u nhU kim loai, hpp kim hda b i n p h i n
tan, lien kim [4] va compozit nl'n kim loai [8]
Mdt vii nam trd lai day, Trfldng Dai hpc
Bich khoa H i Ndi da nghien cflu ky thuat ECAP
de che tao vat lieu (Ti v i Al) cd cau true silu min
trong chfldng trinh hpp tic nghiln cflu qudc te
gifla TTNC Vat lieu hpc vdi Vien KIMS eua Hin
Qudc (Korea Institute of Materials Science) vi d i
cd nhflng ket qua cdng bd trin eic tap chi khoa
hpc ehuyen nginh [11] Tuy nhien, ky thuat ECAP
van edn ban che trong quy md phdng thi nghiem
do: i) sfl dung nhilu thao tie thu cdng trong q u i
trinh van hanh cung nhfl vile di ehuyen phdi gifla
mdi lin ep; ii) chieu d i i phdi tfldng ddi ngan n i n
chi flng dung cho cac chi tiet ed kich thfldc gidi
han; iii) phan dau va cudi mau thfldng cd cau true
khdng ddng nhat, xuat hien vet nflt rdng, phai cit
bd lim ling phi mpt Iflpng Idn vit li|u Nhflng
van de niy dan tdi gii thinh eua vat li?u sieu mjn
che tao bang phfldng p h i p ECAP cao, khdng hieu
qua
De khae phue cic ban che tren, ky thuat ep
liln tue tren be mat (Continuous Confined Strip
Shearing, C2S2) 114] dang dflpc eic n h i khoa hpc
tren the gidi tap trung nghiln cflu v i phat tril'n de
cd the d i p flng dflpc quy md sin xuat Idn Ky thuat
n i y l i sU ket hpp cua ECAP vdi qua trinh day ep
lien tuc bang cic phUPng phap khic nhau Trong
do, ky thuat ep dun lien tuc bang ma sit
(Contin-uous Frictional Angular Extrusion CFAE) [17] li ddi tflpng md phdng edng ngh? trong cdng trinh niy (hinh 1) Ky thuat CFAE la sfl ket hpp cua ECAP vdi q u i trinh ep dun lien tuc vat li|u bang cich sfl dpng ma sil eua true cin qua Iflc ep len be mat mau
Hinh 1 - Sdsddd ky thudt Continuous Frictional Angular Extrusion (CFAE)
Ke tfl gifla the ky 20, phfldng phap mo phdng sd tren cd sd thuat loan p h i n tfl hflu ban (Finite Element Method, FEM) la mdt trong nhflng each tiep can nghiln cflu dflpc i p dyng tren nhieu ITnh vUe khoa hpc v i cdng nghe Phfldng
p h i p n i y ed the md phdng tUPng ddi chinh xac cac q u i trinh vat ly xiy ra trong vat rin Cich tiep can niy d i dan tdi nhieu ket q u i trong nghien cflu
v i phit trien phUdng phap bien dang deo minh lilt tai nhieu phdng thi n g h i | m tren the gidi, giiip cie n h i khoa hpc p h i n tich, d i n h gii mdt each tfldng minh qua trinh cd-nhi?t xay ra trong loan
bp the tich cua khdi vit li|u cung nhfl qui trinh cdng nghi SPD
Trdng cdng trinh nay da bfldc dau thiet lip md hinh cdng n g h | 2D q u i trinh ep dun lien tuc bing ma sit trong kenh gap khuc tiet dien khdng ddi (CFAE) Da flng dung phan mem
DE-FORM™ 2D [20] tren ca sd thuat toin phan tiS
hflu ban (FEM) de md phdng qua trinh cdng nghe 2D CFAE Cae thanh phan flng suit (theo phfldng
X v i Y) tic dpng len mau khi qua gdc kinh ECAP dflpc p h i n tich Anh hfldng cua cic thanh phan flng suit nay trong q u i trinh keo-nen cac phin to h^it gia tfldng da dflpc md hinh hda Nhd viy da lim sing td sfl phan bd cung nhfl bien thiln bi^n dang tren tflng phan v i tai cac diem da l\ia chon
Trang 3NGHIEN cflu - TRAO 06l
cua mau nham giai thich cP ehe lim nhd hat trong
qua trinh CFAE
2 M O H I N H H O A V A M O P H O N G SO QUA
TRINH CFAE
Hinh 2 l i md hinh ddng hpc cho ky thuat
CFAE trong bai toin md phdng 2D dflpc thiet ke
tren chfldng trinh DEFORM'" 2D Mau l i md
hinh vat lieu bien dang deo ed dang thanh, kich
thfldc (255 X 10) mm dflpc chia Ifldi vudng vdi
2000 phan tfl
Hinh 2 l i md hinh hinh hpc cho ky thuat
CFAE trong bai toan md phdng hai chieu (2D)
dupc thiet ke trin chflpng trinh DEFORM'"
Mau li thanh dai vdi md hinh vit lieu bien dang
deo CO kich thfldc (10 x 255) mm va dfldc chia
ludi vuong vdi 2000 phan tfl
Hinh 2: Md hinh cdng nghe CFAE; 1- true cdn,
2- khudn tren, 3- khudn dUdi, 4- phdi ep kich thUdc
(255x10) mm
Kinh 3: Dd thi dng sudt - bien dang cda hdp kim
Nitinol
True can v i khudn dflpe Ifla ehpn vdi md hinh vit lieu tuyet doi cflng Khudn trin v i khudn dfldi tao thinh kinh vio v i kenh ra eua ky thuat ECAP vdi khe hd khdng ddi la 10 mm, cd gdc kenh chinh cD = 120" v i gde Iflpn Y = 0" True cin
cd ban kinh R = 70 mm ddng vai trd ep tao ap Iflc day mau vio kinh ECAP
H i n h trinh cua true ein gdm hai giai doan:
- Giai doan 1: giai doan tinh tien de ep
mau vdi tdc dp v = 1 mm/s
- Giai doan 2: giai doan xoay de day mau
vdi tdc dp V = 0,10472 rad/s (1 vdng/phut) Trong nghiln cflu niy, vat lieu dflde Ifla chon l i hpp kim Nitinol (51% Ti - 49%Ni) ed dang thanh vdi mddun d i n hoi l i 83 GPa, he sd Poatxdng l i 0,33; ma sit gifla true cin vdi mau l i
1, gifla mau vdi khudn l i 0,05 (gan nhfl ly tfldng)
v i dflpe ep tai nhiet d6 25''C Dfldng cong flng suat-bien dang eua m i u trin dd thi eua hinh 3 Cae thdng sd cua vat lieu dflpc trieh d i n trong sach "Smithells Metals Reference" 121]
3 KET QUA VA THAO L U A N
3.1 Phan bo flng suat Hinh 4 la ket q u i phan bd cua flng suat trong phflpng X (a) va phfldng Y (b) tai 5 dilm tren mau d gde kinh 120° nham giai thich qua trinh biln dang khdng dn dinh v i thay doi hinh ding, kich thfldc cua cie md hinh phin to trong bii toin md phdng Thanh phan Ung suat theo phfldng Y l i keo ddn v i xap xi bang gidi han chay cua vat Heu Day ehinh l i thanh phan tao nen flng suit tiep tdi ban d l vat lieu cd the biln dang deo Hdp kim Nitinol cd cau true da tinh the gdm nhieu hat tinh the da canh, mdi hat d i u cd mdt dinh hfldng rilng Dfldi tie dung cua Iflc ep dun tfl phia true ein, khdng phii tat ca eac hat deu cd the tham gia q u i trinh trfldt ma chi cd h a t ' ^
Trang 4NGHIEN CUfU TRAOD(!)l
n i o CO mat trflpt vi phflpng trflpt thuan Ipi nhit
(thfldng la mat trflpt vi phfldng trflpt tao vdi iflc
mpt gde 45" th&o dd flng suit tilp Idn nhat) mdi
cd the trflpt dflpc
Dudi tic dpng cua Ung suit klo khdng
diu cae phan id bj xoay di mdt gdc nhit dinh theo
phfldng Y Su dinh hUdng khdc nhau cua cae mat
trflpt, phflpng trflpt so vdi phfldng tii eUa eae
hat can ke dan den sU tic ddng tUdng hd gifla cdc
hat O mpt phan trin be mil eua hat, Ung suit tde
dpng tang len da hd trp t h i m cho sfl hinh thinh
va ehuyen ddng cua lech Mat khic, flng lUe dd cd
the tao thinh mpt ngau Iflc, lim quay hat Kit q u i
l i dinh hudng cua m i l vi phfldng trflpt thay ddi
ed Ipi cho qua trinh bien dang deo
t o i n md phdng can xac djnh ti le keo-nen tren cac
p h i n td hinh trdn nham t h i y dd0c hinh thai bien dang khi di qua gdc k i n h , tfl do cd thi phin tich
dflpc cd che lim nhd min hat eCia vat lilu trong ky ihuilCFAE
TU kit q u i md phdng, khi mau dflpc ep qua gde kinh cic phan td hinh trdn hi bien d^g, keo dii t h i n h cic hinh clip v i da xoay di mpt goc nhit dinh (hinh 5) Khi di qua gdc kinh 150", vung (1), cic p h i n td hinh trdn ban dau dflpc k^o dai vi xoay di mpt gdc, kit q u i cho thay cie phan
td bi keo dii 21 %, nen 15% Tiep tue qua gdc kenh 120", vung (2), p h i n td biln dang manh hdn va bi keo dii do tie dpng eua Ung suit theo phUdngY
t h i n h eac hinh elip ddng true
(b| \Jng suit Iheo phaong
Nhu da trinh biy d trin, tai gdc kinh 120°,
do sU ehuyen hudng dot ngdt, t h i n h phan ilng suit theo phuong Y tic dpng lam cic mat tinh the bj xd lech, kit q u i l i cac hat tinh the bi keo dii (bien dang) theo phUdng trUdt tdi 65% Tren hinh 4a Ung suat theo phfldng X bao gom ca hai
t h i n h p h i n keo (= 100 MPa) v i nen (= 600 MPa) Thinh phan flng suit kid khdng dang ke dan id! eic p h i n td bi nen lai theo phfldng X Nhfl viy khi
di qua kenh 120", p h i n td bi keo dai tdi 65%vibi nen lai tdi 43%
Hinh 4 - Phan hd vd hien thien dng sudt qua 5 diem tai
gdc kenh theo phUdng X (a) vd phUdng Y (b)
Ngoii ra sfl quay eua hat dan den vile hinh
thanh to chUe textua, phfldng mang cua kim loai
cd xu hudng song song vdi nhau de tao eac hat
ddng true Kha nang biln dang deo tang lin lam
vit lieu tang dp deo do sU khae biet theo phfldng
mang eua hat giim
3.2 Cd che b i l n dang trong CFAE
De lam rd them tic dpng eua cac t h i n h
phan flng suat keo-nen ddi vdi cd ehe bien dang
cung nhfl sfl thay ddi cau true v i kich thfldc hat
trong qua trinh CFAE, cic hat ban dau eua vat l i | u
dflpc gia thiet l i cae p h i n td hinh trdn Trong bai
%
\ , \
/ ^ ^
VliV«r
Hinh 5 - Tile keo-nen theo cdc chieu do khi mdu di qua cdc gdc kenh sau mgt lan ep
Qua trinh bien dang nay l i m eac hat thay doi hinh dang, kich thfldc va p h i vd cau triic ban dau nen td chflc hat nhan dflpe thudng co to chiJc sdi sau khi bien d^ng m a n h (nhfl trdng ky thu^t ECAP) Qua trinh ep khdi vat lieu nhilu lanvcli eae 10 trinh k h i c nhau, vdi mflc bidn dang rSt Idn
Trang 5se lam cho to ehUe sdi n i y de xay ra cd ehe song
tinh, gop phan lim tang sd lUpng hat, nghia la
giam kieh thUdc hat ban dau Day ehinh l i ed sd
ciaa eP ehe tao thanh eic hat cd eau true silu min
trong ky thuat ECAP
3.3 Phin bd va bien thiln bien dang
Hinh 6(a,b) l i kit q u i md phdng bil'n
dang eua mau tai thdi dil'm eudi eung eua mdt
lan ep vdi toe dp quay cua true e i n khdng ddi v =
0,10472 (rad/s) TU kit qua nhan thay cd ba vung
mau di qua lim tang bien d^ng:
Vung 1: vung true cin I p xudng m i u de tao ma
sit gay bien dang d i n hdi
Vung II: vung gdc kenh thfl nhi't vdi O = 150°
Vung III: vung gdc kenh thfl hai vdi O = 120"
Kit qui md phdng cdn cho thay mau bat
dau bien dang tai vung thfl nhat (1), tang t h i m
biln dang khi qua vung gdc kinh 150" (II) v i
tiep tue bien dang manh khi di qua gde kenh
120o (III) Bien dang eua mau dat dflpc sau khi
di qua goc kenh niy l i tdng hpp bien dang cua e i
ba vung trin Gia tri bien dang dat cao nhat l i =
1,13 (113%) (tren hinh 6a bieu thi bang vung m i u
do), kit qua niy hoin toin phu thudc vio die tinh
hinh hpe eua khuon chpn ban dau
Biln dang tinh dflpc bang each thay eac
gia tri gdc kenh va gdc Iflpn v i sd lan I p N = 1 vio
phfldng trinh dac trflng cua ky thuit ECAP [3]:
Cng vdi gdc kenh ® = 150°, gdc lUdn Y =
Oo se tinh duoc ket qua bien dang e V 0,3 (30%)
Vdi gdc kenh <D = 120°, gdc Iiion Y = 0° cd ket qua
Men dang £ * 0,6 (60%)
Nhu vay qua cic vimg II v i III, tong bien
dang cua m i u dat duoc e^ = 0,6 + 0,3 = 0,9 Ket
qua bien dang trong tinh t o i n bang phUcfng phip
md phdng cao nhat dat dtloc = 1,13 Do chenh
lech nay mdt phan do sai s6 bdi phuong p h i p sd
vi do biSn dang (= 0,13) khi true cin ep Ien miu
Ket q u i hien thi mau dd tuong dng phan bd bien dang Idn nhat cho thiy ket qua md phdng h o i n toin phii hop vdi ket q u i tinh toan Til ket qua
md phdng nhin thiy bien dang tai phan phia tren cua mau Idn hon phan phia d i y mau, sU sai khic niy ngoii yeu td ma sit gid m i u va thinh khudn thi cung cd i n h hudng cua gdc kenh 0 va gdc luon Y [231
Effective SIrain, imWmm
Strain inmitant
Hinh 6 - Phdn bd vd bien thien bien dang cua mdu
sau mpt lan ep CFAE
Kit qua md phdng edn cho thay bien dang cua mau dat dUde tUdng ddi ddng deu dpc theo chilu d i i cua miu, bien dang cd gia tri tfl 0,8 den 1,15 trU phan phia dau cua miu Do vung dau mau ed chfla mat tfl do v i khdng di qua ba vung bien dang da n l u trin, n i n biln dang dat dflde khdng ddng deu va dat gii tri thap nhat = 0,15
Hinh 6b la do thi bil'u dien qua trinh bien thien bien dang cua mau Nitinol khio sat tai 5 diem doe theo chilu d i i cua mau Nhfl da bilt, cd
ba giai doan (1,11 v i III) lim tang bien dang eua mau, dieu n i y dfldc the hiln ro tren dd thi vdi ba mflc flng vdi ba giai doan trong qua trinh CFAE
Giai doan I khi m i u bi nen nhe, mfle dp bien dang dat dflpc £, = 0,08 Giai doan II l i khi mau di qua gdc kinh 150o, ket qua trin do thi la £„ = 0,36 (thay rd d c i 4 die'm 1, 2, 3 v i 4 Giai do^n 111 l i khi mau di qua gdc kenh 120°, g i i tri biln dang dat £|,| = 1 (rd nhat d hai dil'm 2 v i 3) Gia tri bien dang dat cflc dai la = 1,13 va gifl nguyen din khi ket thue q u i trinh Ip I"
Trang 6NGHIEN Cflu - TRAO OOl
Cung tren hinh 6b, kel q u i bien thiln bien
dang tai dil'm 1 ed sfl k h i c bi|t Gii tri bien dgng
cua nd dat dflpc Idn nhat li ~ 0,4 so vdi 1,13d cae
diem khao sit khae nhfl diem 2 v i 3 Dilu n i y ed
t h i giai thich r i n g dicm 1 khdng di qua goe kenh
150 o v i en mpt m$t tfl do nen ngoii vi^e bien
dgng dan hdi d i m i t , cae m$t trflpt eung dflpe
thoit de d i n g tao ra edc b i e ehiy lien m i t Ifl do
lim giim sfl biln dang v i tang tinh khdng đng
n h i t cua vat li^u tiji vung niy cua maụ
4 KET LUAN
Phin tich Irang thai flng suit keo-nen
theo chieu X v i Y t i c dpng l i n cac p h i n id khi
di qua gdc k i n h cho phep giii thich cd e b l trflpt
dan tdi eau true hat gii tfldng bj keo d i i v i xoay
di mpt gde nhat dinh trong qua trinh CFAẸ
Ket q u i md phdng mpt lin ep cho bill
mflc dp k l o va nen (keo dai ldi 65% v i bi nen lai
tdi 43%) p h i n td hgt (cau true) gii tfldng l i eae
hat ban d i u eua vat lieu da giai thich dflpe phan
nao ed ehe tao t h i n h eic hat vat lieu silu min
trong ky thuat ECAR
Ket q u i cung d i dfla ra sfl p h i n bd v i
bien thien bien dang cua mau nham danh gii anh
hfldng cua cic thdng sd hinh hpc v i ma sit den
mflc dp bien dang n i y trong q u i trinh CFAẸ •
Ldi cdm dn
Bai toan md phdng thfle hien bdi Nguyen
Trfldng Minh va Dd Thi Hai Yen tai Phdng Thi
nghiem Cdng n g h | kim loai, Trfldng Dai hpc
Bich khoa H i Ndị Phan mem DEFORMTM 2D
Ver.9.1 dflde hd trp bdi Phdng Thi nghiem Vat lieu
nand (Structural Nano-Material Processing Lab.),
Trfldng Dai hpe POSTECH, H i n Qudc v i kinh
phi do Quy p h i t trien Khoa hpe 8f Cdng nghe
Qudc gia (NAFOSTED) ma sd: 107.02.2010.11
cap •
Ngiy nhan bai: 04/6/2012
Ngiy phan biln: 04/7/2012
Ngfldi phan bien: GS.TS D o Minh Nghiep
Tai lieu tham khao:
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|.T| Y Iwahashi, ) Wang, Z Horn.ị M Nemoto and X G l ingdon, Scripta Mater 35 (1996) 143-146
|4|, Ị Olejnik and Ạ Rosochowskị Bulletin of the Polish Academy of Scientc-s and Technical Sciences 53,4 (2005)
|5] D H Shin I- Kim, J Kim, Ỵ S Kim and S Ị, Semiatin, Ặla Malcriaiia 51 (2003) 983-996
[6] Ị Kim, J Kim, D H Shin, C S Lee and S K Hwang, Materials Science and Eng A342 (2003) 302-310 Ỉ] S C Yoon, S Ị Hong, M H Sec, P Quang and H.S Kim, Journal of Korean Powder Metallurgy Institutẹ 11(2) (2004) 87-94
[8| P Quang Ỵ G Jcong S H Hong and H S Kim Key ling Materials, 326-328 (2006) 325-328
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