Cdc kit qud dat duac ldm ca sa toi uu qud trinh thuc nghiem vd tiet kiem thai gian kiem tra cheo cdc tinh todn bang phuang phdp so, tir do di ldm tien de cho viec phdt triin cong nghi
Trang 1NGHIEN CUfU-TRAO Ddi
U'NG DUNG P H A N M £ M C O M S O L M 6 PHdNG QUA TRJNH NUNG
C A M U'NG D^N TRANG T H A I B A N L 6 N G C O A PHOI HE
HOP KIM NHOM TRONG CONG NGHE TAO HJNH THIXOFORMING
THE APPLICATION COMSOL SOFTWARE TO SIMULATE THE INDUCTION
HEATING PROCESS TO ALUMINIUM ALLOY'S SEMISOLID STATE IN
THIXOFORMING PROCESS
NguySn Vinh DyS Trinh VSn Quoc^ Luu Phwong Minh'
'Sd Khoa hpc va Cdng nghe TR Hd Chi Minh
^Trudng Dai hgc Su pham Ky thuat TP Ho Chi Minh
'Trudng Dai hgc Bach Khoa TPHd Chi Minh
Ky thudt Thixoformingyeu cdu gia nhiet phdi din trgng thdi bdn long truac khi tao hinh
sao cho nhiet do duac phdn bo dong deu trin todn bg thi tich cua vgt nung Td chuc ti vi cua phoi
CO dgng cdu vd co ti le pha ran- long theo mong mudnphdn bd deu Trong qud trinh nung, mgt sd
hien tuang vgt ly se ldm dnh huong den tinh chdt bdn long cua phdi Trong nghiin cicu ndy, nhom
tdc gid su dung phuang phdp ly thuyet truyin nhiet, phuang phdp so kit hgp vai phuong phdp mo
phong bdng phdn mem comsol di xdc dinh chiin lugc nung din trgng thdi bdn long Cdc kit qud
dat duac ldm ca sa toi uu qud trinh thuc nghiem vd tiet kiem thai gian kiem tra cheo cdc tinh todn
bang phuang phdp so, tir do di ldm tien de cho viec phdt triin cong nghi a mice do cong nghiep vd
tdi lieu tham khao cho viic ndng cao hieu qud phuc vu cho cdc nghien cim trong linh vuc nung cdm
ung noi chung vd tao hinh vgt lieu a trgng thdi bdn long noi rieng
Tfr khoa: Ky thudt thixoforming, nung cdm img, phuang phdp so, phdn mem mo phong
comsol
ABSTRACT
Thixoforming technique requires casting metal alloys when they are partial liquid and partial
solid before the material flow into the die cavity under pressure, the temperature distribution must
be uniform within the billet at the end of heating, in order to obtain a good microstrucre In this
papers, the authors use theoretical heat transfer, numerical method and combine with the Comsol
software simulating method to confirm and suggest strategies for practical process aiming to save
re-inspecting time of the calculation process by numerical method This is the basis to develop
technology at industrial level and create basic premises in raising the application effects for studies
of induction heating (in general) and thixoforming techique (in particular)
Keywords: Thixoforming technique, induction heating, numericalmethod; the Comsolsimulating
software ^
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Trang 2NGHIEN CUfU-TRAOD6I
1 G I O ! THIEU
Ky thuat tao hinh vat lieu mdi eo ten la
tao hinh vat lieu d trang thai ban long da dugc
bit diu va phat triin bdi Giao su Merton C
Flemings ~ Vien Ky thuat Masasuchet, Hoa Ky
Trong nhilng nam gin day, ky thuat tao hinh nay
da dugc bit diu thuong mai hda dua vao san
xuit cong nghiep So vdi cac phuong phap tao
hinh truyin thdng d hang thai chay Idng hoan
toan, thi kim loai trong tao hinh d hang thai ban
long dugc dieu khien den hang thai nua dac va
nua Idng nham cho ddng chay cd dp nhdt cao
han trong suot qua hinh tao hinh do do chat
luang vat due cung cao hon vi vay khac phuc
dugc tinh hang quan khi hong vat due Cdng
nghe naycho chat lugng be mat vat due tdt, kha
nang chiu keo cao, rd be mat d miic thap, vat diic
CO td chuc te vi tot, tiet kiem dugc nang lugng
hong qua trinh tao hinh, dac biet doi vdi nhiing
san pham doi hdi dung sai kich thudc nho [1-6]
Ky thuat tao hinh vat lieu d trang thai ban
long CO hai hudng eong nghe: Rheoforming va
thixoforming Khae vdi phuang phap rheofomiing
la di tir trang thai long xudng trang thai ban long,
phuang phap thixoforming dl tii hang thai ran
den ban long Ky thuat tao hinh theo thixoforming
ddi hdi nung phdi ban dau trudc nham tao ra mdt
cau tnic tot vdi ti le phan ham pha Idng khoang
40-50% Nhiet do nung phai dugc kiem soat
mdt each chinh xac nham dat den sy dong deu
ve nhiet do hen toan bd the rich vat lieu Trong
pham vi nghien eiiu eiia bai bao nay, nhdm tac
gia sir dyng phuang phap nung cam ung phyc
vu cho qua hinh chuan bj phdi ban dau, day la
phuang phap duge sir dung phd biln, dac biet la
hong quy trinh tao vat lieu d trang thai ban long
vi phoi dugc nung khdng tiep xiic tryc tilp vdi
nguon nhiet Nung cam ling cd uu dilm sach,
thdi gian nung nhanh va dac biet nguin nang
lugng dau vao dugc kiem soat de dang Tuy
nhien, nung cam ung co nhuge dilm co hmi la
nhiet do hen toan bg thi tieh vat lieu khdng ddng
d i u do hieu ling be mat, hieu ung dau cudi (hieu ling ket thiic xay ra d giai doan cudi qua trinh nung), hieu ling dien hi, mgt hong nhihig yiu
td anh hudng den qua trinh nung Muc tieu ciia nghien eiiu la de ra chien lupc nung hgp ly va mgt trong nhilng cdng cy hd h g giup cho ket qua nghien ciiu kha thi la ket hgp phuang phap tinh toan qua hinh nung bang phuang phap s6 va kiem tra cheo bang phuang phap mo phdng sir dung phan mem comsol - day la phuang phap duge cac nha nghien ciiu sii dung phd bien, do ciing la ly do ma md hinh hoa va md phdng so qua trinh nung cam ling duge cae chuyen gia quan tam va phat trien [6-7]
Hinh 1.1: Phdi nung 6 trgng thai hdn long
2 NOI DUNG NGHIEN CUtJ
Trong nung cam ling, gia tri eua mat do dong dien tdi da la d tren b l mat eua ehi tiet va
se giam mdt each nhanh chdng khi nd di sau vao ben hong tam Hien tugng nay dugc gpi la hieu ung be mat Do hieu ling be mat nen nen hau het ngudn nhiet deu tap trung len be mat cua chi tiet Khoang 86% nhiet lugng duge eung cap d lop
be mat va dupe ggi la chieu sau thim, chieu sau nay se giam khi tan sd tang do dd de dam bao dp chenh nhiet dp trong toan bp thi tich cua phoi nung, vl the de giam thilu tii da hieu dng be mat
va tdi uu thdi gian nung, nhom tac gia su dung chien lugc nung viia gia nhiet va vua lam nguoi dong thdi tren be mat cua phdi nung va su dung tin sd nung 20 KHz de khao sat su thay ddi nhiet
dp giiia tam va be mat phdi
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Trang 3NGHIEN CUfU-TRAO B 6 I
Trong qua hinh tim ra chien
lugc tren, nhdm tac gia su dung
phuang phap sd dl tinh toan, uu diem
cua phuang phap sd la phan rich toan
hpc dl tim ldi giai ciia qua trinh la rit
chat che, khai niem vat ly va logic suy
luan rat rd rang, nghiem dugc bieu diln
dudi dang ham sd nen thi hien rd rang
mue dg anh hudng cac nhan td din su
phan bd ciia trudng nhiet dp
Ngoai ra, uu diem cua phuang
phap sd la chd nd ed the giai quyet
dugc cae van de truyen nhiet trong thyc
te ma cac phuang phap khac khdng lam
dugc, ddng thdi tuy theo dung lugng
cua may tinh, tdc do tinh toan tang cao
thi pham vi ung dung phuong phap sd,
quy md; Toe do va dp chinh xac tien
trien rat nhanh nen no da trd thanh mdt
phuong phap hihi hieu de giai cac bai
toan dan nhiet phuc tap hong ky thuat
Va de giai bai toan truyen nhiet
hen, nhdm tac gia su dung phuong
phap sai phan hiiu ban, su dung tri nhiet
dp gan dung tai cac diem nut (ling vdi
khong gian va thdi gian xet) cua phan
tl (phin td) dl thay the cho su phan bd
nhiet dp lien tuc thyc te trong vat the,
dem nghiem ham sd phan bd nhiet dp
lien tyc chuyen hda thanh nghiem ciia
tri nhiet dp t^i cac diem nut, thdng qua
each nay se dem vin dl giai phuong
trinh vi phan din nhiet chuyen thanh
giai he phuang trinh dai sd tai cac diem
mit cua phan to Do dd, phai chia nhd
vimg xem xet bai toan, thiet lap he
phuong trinh dai s6 nhiet dp t^i cac
phan td va giai, do la ndi dung chii yeu
eua phuang phap sd [8]
3 MO HINH HOA VA MO PHONG SO V^T LY CUA QUA TRINH NUNG CAM ITNG
3.1 Md hiuh hoa va giai bai toan toi ini b^ng phirong phap C G M (Coujuntion Gradient Method) Chi tiet dugc nung bdi cum thiet bi cd dae tinh ky thuat: Dien ap vao 220V, cdng suat 3Kw, tan sd nung dao dgngtul5KHz-25KHz
« Mo hinh vat ly cua qud trinh nung cam ung
- Phdi nung la hgp kim nhom A356, hinh try cd dudng kinh 80 mm, chieu cao la 50 mm, dupe dat theo phuang thang dung (Hinh 3.1), ngudn nhiet ben hong dupe tao ra nhd su cam ling dien tir de dam bao dupe ty
le pha ran va pha Idng la 45 - 50% thi phdi nung dugc gia nhiet din 585°C
Hinh 3.1: Md hinh vgt ly sit dung cho qud trinh nghien cuu
b Hffp kim A356
Do tinh chat vat ly ciia phoi nhom A356 cd khoang nhiet dp chuyin trang thai tii dong dac sang long hoan toan tuong ddi Idn, khoang 65*'C nen rat ling dung de tao hinh phoi nung d hang thai ban Idng do dd hong nghien ciiu nay hap kim Nhom A356 dupe sir dung de tien hanh cac nghien ciiu va hgp kim nay cd thanh phan hoa hge nhu sau:
g- 3.1 Thdnh phdn hod hgc ciia hgp kim Nhdm A356 [11]
Si
6,59
Fe
0,01
Cu 0,12
Mn 0,005
Mg 0,39
Zn 0,005
Ti 0,005
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Nhiet do ma phdi hpp kim Nhdm A356 dat
din trang thai ban Idng f = 50% la khoang 583^
585°C theo nghien ciiu cua nhieu tac gia [11]
Bdng 3.2: Tinh chat vat ly cm hgp kim NhdmA356 [H]
Nhiet dp Dong chay, "C
Nhiet dp dong dac, °C
Nhiet dung rieng cua vat
lieu (J/kg°C)
Dp dan nhi?t ciia vat
lieu (W/m °C)
Khoi luong rieng ciia
chi tijt (kg/m')
615
555
0,454.T(»C) +904,6
0,04.T("C)+153,1
-0,20ST ("O + 2680
c Mo hinh todn cua qud trinh nung cam ung
Mo hinh toan eiia qua trinh nung cam
ling kim loai ban Idng gdm 3 phin:
- Phuang trinh truyin nhiet
- Cac dieu kien bien: Day la su phdi hgp
gida phuong trinh truyin nhiet, phuong trinh
huyen nhipt ddi luu va phuang trinh biic xa
nhiet
- Cac dieu kign ban dau
0 Dieu kifn bien:
• Tair=0: k — = 0
dr
Tair=R: k ^ = qbic«.i+ qii„,„4,(t)
*" <W,n = 5,67x10-' X D,05x [(Ts+273)'+
(T.«„»„+273)a[W/m^]
> qi„^,('):,'=hi6n lugc nung c4n tinh toan trong
timg thoi diem nung, [W/m^]
o Dieu ki^n ban dau:
Tai zH): k— = 0
dz Taiz=H: k £ = qaii,„j,^i„ + q^,^^
Chung ta se tien hanh toi uu hoa ca hai bai toan gia nhiet va lam nguoi thong qua vi$c xac dinh G(t) va q{t) Ca hai ham dSu phai thoa man dieu kien sau:
q ( t ) < 0 G(t) > 0
Phuang trinh truyen nhiet 2 chiSu theo r B^ g'*i quySt bai toan tdi uu tren thi
phuong phap CGM la mot phurnig phap duoc nhom tac gia dS xuit, phuong phap CGM la mgt
- mt- P^"™? phap lap thuooig Suae cac nha nghi6n
"' 'SI CUU ling dung boi vi no khong chi CO tinh hi?u Hay: q^^ cao ma con do dac trung tu hieu chinh cua
1 8 / W\ a / aTx ST ''^""'™ phuang phap ma hudng lap g6m gradi .-.^k(r).r.-j+ ^.[k(I).r.-j + Qjj,„^ = p(T).Cj(D.- ent cua ham muc tieu theo biSn s6, cong them
va theo z (r, z: la bien):
Vai:
Q MrmnB- *^S"™ •*>?' bcH ttong do thict
bi tao ra, [W/m=]
Qbi.>„.g = GCt) X e-^<«-)/«
mgt dai lugng dieu chinh dua tren huong lap truoc, Cu th^:
G""(t)=G«(t)+P"P"(t)
Voi P^ (t) la huong lap, fi^ la kich thuoc
buoc hay he s6 diSu chinh do 1cm ciia bugc, P" (t)
la lien hgp ciia gradient J" (t) tai buoc lap n va huong giam P°' (t) tai bugc lap n-1:
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Thuat toan lap CGM d l giai quyet bai
toan toi uu tren g6m cac buoc sau:
1) Bat gia t h u y a ban dau 0 ° = G„(t), q„ = q„(t),
n = 0;
2) Giai bai toan true tidp vgi G" va q" dd tim T°;
3) Giai bai toan tiem can dd tim gia tri ham nhan
tii Lagrange X.(x,y,z,t);
4) Thay gia tri X(x,y,z,t) vao Gradient cua ham
sai so theo huong G va q;
5) Xac dinh hieu sd T'(x, t,) - T^;
6) Tinh P," va P^" theo cdng thuc sau:
Pi° = - I „[G(t)l +
-LfeWl+rt.Pz"-'
phan hiiu han theo cac budc sau:
- Can eii vao binh dang hinh hgc, tinh chat vat ly cua bai toan dan nhiet thuc te, hen hanh phan rich, thuc hien viec don gian hda mdt each hgp ly d l thilt lap md hmh vat ly phii hop vdi thuc te
- Can eii md hinh vat ly thiet lap md hinh toan hoc hoan chinh, nic dua ra phuong trinh vi phan din nhiet va dieu kien dan vi
- Chia ludi: Dem khdng gian va thdi gian cua bai toan dan nluet dang xet phan thanh cac phan hi hiiu ban (hoac cdn ggi la phan td) theo yeu cau nhat dinh, dung nhiet do d tam nhan td (diem nut) dac trung cho nhiet do cua phan to
- Thiet lap he phuang hinh dai so tai cac diem mit
^ = r'r,
joi)„(Qrdt
/o"D„-.(t)]'dt
- Giai phuang hinh dai so nhiet do cho cac diem nut ta tim dugc tri nhiet dp d tat ca cac diem nut
- Tien hanh phan tich ket qua tinh toan tim dugc
7) Tinh hep tuc cho G"'^'(t) va q"^'(t) theo cdng
thuc sau:
C n - M f t ) = G " ( t ) + P " P " ( t )
q n * i ( t ) = q " ( t ) + P " P " C t )
8) Dat n = n + 1 , h d lai budc thu 2, lap lai cho
tdi khi J"<£
3.2 Ket qua tinh toan
Trong qua trinh tdi uu hoa qua trinh nung
cam ung theo thuat toan CGM; De giai phuong
trinh tniyin nhiet phai kit hgp phuang phap sai
- De viec tinh toan dugc h d nen nhanh chdng
va chinh xac; Viec rinh toan vong lap theo phuong phap CGM va giai bai toan truyen nhiet dugc lap trinh hen phan mem Matlab vdi ket qua tinh toan eu the nhu sau:
Hinh 3.2: Bieu do chien lugc gia nhiet phdi
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Hinh 3.3- Bieu do chien lugc ldm ngudi
Hmh 3.4: Phdn bd nhiet do giUa diem ddu vd diim
cudi cua qud trinh nung cdm irng
TIUI|tD
a) Qud trinh gia nhiet: Ta thiy qua trinh nay
diln ra hong khoang thdi gian tu 0 - 150 giay Luc nay, phdi nung dugc nang nhiet theo dudng cong parabol (hinh 3.2); Ddng thdi vdi qua hinh nay ta cimg tien hanh lam ngudi bl mat chi tilt theo dudng thing tuyIn tinh (hinh 3.3) vdi cudng do ngay cang giam Do hieu ling bl mat nen nhiet do d tam se cao ban d bl mat, tuy vay, nhiet do hong toan phdi nung vin tang diu
Va hong khoang thdi gian nay ta vin phai duy
hi qua trinh lam ngudi bdi vi do chenh nhiSt dp hong phdi nung hong giai doan dang tang va Idn hon lO^C
b) Qud trinh gia nhiet: Qua hinh nay bit diu
dien ra tir 150 - 300 giay phdi nung vin dupe gia nhiet theo dudng eong parabol (hinh 3.2), ddng thdi, ket hgp viec tang cudng do lam ngudi; Tuy vay, theo hinh 3.3 ta nhan thiy nhiSt
do hong khoang thdi gian nay thay ddi va eo xu hudng giam din Do day la qua trinh giu nhiet nen ta thay ro hong khoang thdi gian nay nhiet
do hong phdi nung hd nen ddng diu hon va
dp chenh nhiet dp ngay cang giam den khoang
200 giay thi dp ehenh nhiet dp da nhd han lO^C (hinh 3.5)
3.3 Mo phdng b5ng phan mIm Comsol
a Gi&i thieu phan men Comsol
Hinh 3.5: Bg chenh nhiel do trong qud trinh nung
Nhan x6t:
TCr cae dd thi hinh 3.2, 3.3, 3.4 va 3.5 ta
nhan thiy qua trinh nung hgp kim Nhdm A356
COMSOL Multiphysics la mdt trong nhdng phan mem ndi tieng trong ITnh vuc mo phdng da vat ly Vdi kha nang lien kit cac dang bai toan md phdng khac nhau, COMSOL
CO kha nang ling dung trong cae ITnh vuc nhu:
din hang thai ban long dien ra theo hai giai doan ^'^^ ~ ^ trudng; ca khi; nhiet, luu chit va hda
chinh nhu sau: hpc Cac chiic nang nay dugc trinh bay chi tilt
nhu hinh 3.6.[9]
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MKlw-oMoi* UgU, hdUkUMt
•sa?
SB
"^VT"
1
^-r:;:in—,
1 t ^ - " 1 1 •**'• 1
Hinh 3.7: Qui trinh md phdng gia nhiet hdng tit truang trong phdn mem COMSOL
c Mgt so kit qud tinh todn bang phan mem Comsol
Hinh 3.6: Cdc chiec ndng chinh cda phdn mim
COMSOL
Vdi kha nang md phdng nhu hen, COMSOL
dae biet thich hgp hong cac nghien eiiu chuyen
sau, giup cac nghien ciiu nay tiet kiem chi phi
cung nhu thdi gian thii sai Cac ling dung ndi
bac cua COMSOL hong ITnh vuc co khi nhu
sau:
- Md phdng trao ddi nhiet giiia tudng rin
va chat Idng ben hong, giiia hai hay nhieu chat
Idng khac nhau
- Md phdng ddng chay hong he thdng
ong, cd hay khdng cd hao ddi nhiet hdn lan chat
long
Qua qui trinh md phong nhu hinh 3.7, ket qua gia nhiet dugc thu thap va phan tieh nhu hinh 3.8,3.9, va 3.10
Hinh 3.8: So sdnh nhiet do tgi hi mat phoi giira mo phdng bdng COMSOL vd tinh todn s6
b Cdc bir&c th^c hien tren phdn mem Comsol
Trong nghien eiiu nay, module truyen
nhiet va tii trudng se dugc ling dung nhim md
phdng qua trinh gia nhiet bing tir trudng ed tin
sd cao cho vat due Qui trinh md phdng dugc
trinh bay nhu hinh 3.7
Hinh 3.9: Phdn bd nhiet do cua phoi tai cudi thdi
diim gia nhiet
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' % !
Hinh 3.10: Phdn hd nhiet do tgi mat cat cua phdi
d Sai so giira kit qua tinh toan b i n g p h i n m I m
Comsol va phvong phap sd
Dua vao cac kit qua d hen, ta nhan M y
viee kit hgp ea 2 phuong phap: Md phong so va
md phdng bang phan mem Comsol ho h g dac
luc cho nhdm nghien ciiu dua ra chien lugc nung
phoi: Vira gia nhiet, vira lam ngudi cimg luc, bang
thiet bi nung cam ung se cho ket qua tdt han hong
trudng hgp nay Ngoai ra, hong san xuat thuc te
cac thilt bi tao hmh vat lieu d trang thai ban long
thudng cd dang xoay hdn va thanh billet dugc d|t
diing len theo md hinh thi nghiem vi vay viec ket
hgp qua trinh lam ngudi se lam giam hien tugng
"chSn voi"
Kit qua md phdng bang phan mem
Com-sol cho phep chiing ta quan sat true quan ve trudng
nhiet do ciia phoi hong suot qua trinh nung
4 KET LUAN
Trong bai bao nay, qua trinh gia nhiet eho
phoi hong qui trinh nung ban long da dugc thuc
hien Vdi phuong phap so, ket qua giai bang
Mat-lab va phan mem COMSOL rat phu hgp Khi so
sanh ket qua giiia hai phuang phap nay, gia tri
nhiet dp Idn nhat va nhd nhat tai mat cat cua phdi,
nhiet dp chenh lech khdng qua 30 "C nhu hinh 3.8
Ngoai ra, phuong phap sd eiing eho thay vdi 200
s gia nhiet, nhiet do cua phdi se tang tii 30 "C den
450 "C
Trong cdng nghe tao hinh vat lieu d trang
thai ban Idng thixoforming thi viec kiem soat nhiet
do hong toan bg the tich ciia phdi nung la het sue
quan hpng va cd y nghTa quyet dmh din chit lugng
vat due Chinh vi le do, viec ket hgp giiia tinh toan,
mo phdng sd va mo phong bang phan mIm chuyen
dung Comsol la giai phai phap va la phuang phap kha thi de xac dinh tmh dung din va hpp ly cua
eo sd ly thuyet tdi uu hda qua hdr hinh nung cam ling hgp khn nhdm d trang diai ban long theo cong nghe Thixoforming Trong nghien eiiu nay, cac ket qua tir md phdng bang phan mem Comsol va phuang phap sd giiip chung ta danh gia tinh xac thuc Cling nhu dp tin cay cua chiing, qua do lam
CO sd cho viec trien khai thyc nghiSm duge nhanh chdng va mang lai ket qua mong mudn Phin mIm Comsol cdn giiip cac nhom nghien cdu hong ITnh vuc tao hinh vat lieu, co th§ ling dung nhu la mdt cdng eu md phdng so hpc
da vat ly, gdp phan cung phuang phap so, phucmg phap thue nghiem giai quyet cac van de lien quan khac nhu: Trao ddi nhiet hong ddng chay, sji khuylch tan, day la nhiing van de anh hudng ral Idn den chat lugng vat due.«>
Ngay nhan bai: 12/02/2015 Ngay phan bien: 20/3/2015 Tai lieu tham khao:
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a status report, Modem Casling 41 -3 [2], Midson S, Rudnev V and Gallik R 1999 Semi-solid processing of alu-mmum alloys Industnal Healing 37-41
[3] Jung H K and Kang C G 2002 induction heating process ofanAlSi
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[5] Ko D-C, Mm G-S, Kim B-M and Choi J-C 2000 Finite element analysis
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[6] Flemings M C 1991 Behavior of metal alloys in the semi-solid slatt Met Trans.A22 957-81
[7] Nguyen K T and Bendada A 2000 An mverse approach for the pre-solid casting billet Modelling Simul, Maler Sci Eng.8 857-70
[i].l^piyen'Than]\Hio Phutmgphap sai phan liSvhgn ung dyng im^
CO hpc lini chdl linh loan va Iruyin nhi^l Dai hgc quoc gia Thanh pw
H6 Chi M i n h ' 2 0 0 9
[9] Dang Thanh Tnmg Comsol nen tdng va ung difng irong md phait s6 Dai hoc Qu6c gia Thanh ph6 H6 Chi Minh - 2014
[10] Midson S va Brissing K.Semi-sohd casimg of aluminum alloysii status repor Modem Casting - 1997
[ I I ] MaoWei-min, Zheng Qiu, Zhu Da-pmg Rheo-squeeze casting p( semi-sohd A356 alurmnium alloy sluny Eisevie Press/trans Non ferroiB Met Soc China 20 (2010) (1769-1773)
ISSN 0 8 6 6 - 7 0 5 6
TAP CHi CO KHI VIET NAM, S6 3 nam 2015