NGHIEN CUTU-TRAODdl
CONG NGHE HAN CHE TAO C H I TIET MAU CO KHUYET TAT NGAM X I SlT DUNG
PHU'QNG PHAP HAN SMAW
RESEARCH AND PROPOSAL ON WELDING TECHNIQUE FOR GENERATING SLAG INCLUSION DEFECT
Dang Thien Ngon, Le Chi Cu-ong Truong Dai hoc Su pham Ky thuat TP. H6 Chi Minh
TOM TAT
Chi tiet mau moi ghep hdn cd khuyet tat ngdm xi da vd dang duoc su dung rong rat trong cong tdc nghien cuu cdc khuyet tat hdn vd phuc vu cho cdng tdc ddo tgo ky thuat vien kiem tra khuyet tat moi hdn bdng phuong phdp kiem tra khong phd huy (NDT). Viec chi tgo chi tiSt mdu vai khuyit tat ngdm xi chi CO the phat hien duoc bdng phuong phdp kiem tra NDT Id mot cdng viec kho khan, yeu cdu phucmg phdp dieu khien cdc thong so hdn. Bdi bdo trinh bay cdc ket qud nghien ciru, thu nghiem cong nghe che tao chi mdu moi ghep hdn cd khuyet tat ngdm xi bdng phucmg phdp SMAW. Cong nghe de xudt vd ky thuat hdn duac thuc hien theo tieu chuan A WS, khuyet tdt ngdm xi cua chi tiet mdu duac kiem tra, danh gid bdng phuong phdp kiem tra sieu dm vd X-quang.
Tir khoa: Xi; Nggm xi; Sieu dm; X-quang; SMAW; GTAW.
ABSTRACT
The weld sample having slag defect is used widely in device sampling and training technician in weld inspection using NDT techniques. Producing the weld sample with slag inclusion that may be detected by NDT techniques has difficulties and requires method of controlling welding parameters.
This research presents the technology of generating slag in SMA W method. The welding parameters are based on A WS and the sample having slag inclusion will be measured and verified by using ultra- sonic and X-ray radiographic method.
Keywords: Slag; Ultrasonic; Radiographic method; SMAW; GTAW.
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1. DAT VAN DE
M6i han c6 khuyet tat ngam xi c6 the dupe sir dung rong rai trong cac cong viec nhu:
dao tao, danh gia nang luc nghi nghiep ky thuat vien NDT, nghien ciiu phat trien ky thuat NDT, nghien ciiu tinh chat co hpc cua moi han,...Chi tiet mau c6 khuyet tat ngam xi duac che tao phai dam bao cac tinh chit ca ly tuong tu nhu khuyet tat ngam xi tu nhien [9].
Viec nghien cim, che tao cac chi tiet man CO khuyit tat ngam xi la mpt cong viec kh6 va dang dupe quan tam nghien cim. Hien tai, cac khuyit tat ngam xi co thi duoc che tao bang each chen xi vao duong ban hoac bang each thay doi chi dp ban [9,12].
Bai bao dl xuit cong nghe che tao chi tiet man co khuyet tat ngam xi dupe thuc hi^n theo tieu chuan AWS [13]. Cac chi tiet mau che tao se dupe kiem tra bang phuong phap sieu am va chup anh phong xa.
2. KHUYET TAT NGAM XI
Moi han bi khuyet tat ngam xi la moi han ma xi han bi ket 6 ben trong duong han (khong the nhin thay true tiep dupe bang mat - hinh I) hay 0 tren duong ban (c6 the nhin thiy true tilp bing mit, hinh 2) [9, 15].
Hinh 2: Ngdm xi hc» nvn duong h
Khuylt tat ng|m xi duoc chia thanh 3 dang: Ngam xi tir thu6c bpc que han (ban SMAW), ngam xi tir thufic han (FCAW, SAW,...) va ngam xi tic vat Hen ban [8, 15].
Bai bao nay se giai thieu cac ket qua nghien ciiu, dl xuit c6ng nghe han tao khuyet tat ngam xi tir thudc bpc que han ttieo dang duong voi ky thuat "tao hdc bay xi" su dyng phuong phap han SMAW [11].
3. DE XUAT CONG NGHE
Cong nghe chd tao chi tiet mau voi khuyet tat ngam xi sii dung phuong phap han SMAW dupe dl xuit dua tren cac tieu chi:
- Cdng nghe han dupe xay dung dya theo tieu chuin AWS Dl.l [13, 14];
- Khuyet tat khdng the phat hien dupe bang cac phuong phap ngoai quan;
- Khuyet tat c6 the phat hien duoc bang cac phuong phap kiem tra khdng pha huy [4-7,12];
- Vipc trien khai va ling dung cdng nghe thuan tien, ti le thanh cdng lan;
- Yeu cau tay nghe ngu6i thp dat chiing chi han SMAW 3G theo chuan AWS hoac cac chung chi, bang cap tuong duong [2, 10, 13].
Tren co sd cac tieu chi tren, cong nghe dl xuit sii dung phuang phap han SMAW g6m 3 buoc:
- Budc I; Lira chpn vat lieu;
- Buac 2; Thilt kl mdi ghep;
- Budc 3: Tao khuyit tat.
3.1. Lijra chon vat lieu
Viec lira chpn vat lieu co anh hudng lan den cac phuang phap kilm tra khuyit tat mdi han. Do do vat lieu dupe chpn lua theo cac nguyen tic sau:
- Vat lieu ca ban duac lira chpn khong gay bat ky tro ngai nao den phuang phap kilm tra du ki6n (sieu am va X quang) [12].
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NGHIEN CUfU-TRAO OCl
- Vat lieu che tao m l u thir phai khdng dupe phan lap, khong lan tap chit phi kim loai va cac tap chat khac [6].
- Viec lua chpn vat lieu co ban can xet den muc dich cua ngudi sir dung san phim.
- Cac vat lieu c a ban va vat lieu han dupe lira chpnphai tuan theo tieu chuin AWS D l . l [13].
3.2. Thi^t k^ moi ghep
Ve CO ban, kich thudc hinh hpc cua mdi ghep han khdng anh hudng nhieu den viec phat hien cac khuyet tat. Phuang phap tao khuyet tat n g ^ xi CO the dupe thuc hien tren moi han nhieu lop, cac mdi han c6 the la mdi ban goc hoac mdi han giap mi [15]. Phuang phap kiem tra bang sieu am yeu cau mau co khuyet tat nam trong khoang 10% - 90% chieu day cua chi tiet ban; Phuang phap X quang yeu cau trong khoang 25% - 75%
[12]. C) day, de co the su dung ca 2 phuang phap d l kilm chiing, chi tiet mau duoc che tao se c6 khuyit tat nam trong khoang 25% - 75% chieu day cua chi tilt han. Dung sai kich thuoc chi tiet theo chilu dai, rong, day va duong kinh la 10%
[12]. Bai nghien cuu trinh bay khuyet tat mdi ban ngam xi tren mdi ghep kieu V don (single V) cd thilt k l mdi ghep nhu d hinh 3 vdi cac thdng sd dupe can cii theo tieu chuan AWS [13].
- Han lop I6t (I) bing GTAW (hinh 4);
- Han lap (2) d i n lap (n-2), tao khuyit tat ngam xi bang SMAW tai vi tri can cay khuyet tat. Chieu dai khuyet tat mong muon dupe thuc hien bing each dieu chinh gdc dp que han sao cho mdi ban chi ngau mpt canh vat ban ma khdng lam ndng chay canh mdi ban con lai. Chieu cao cua khuyet tat phu thudc vao sd luong cac lop han.
-Hai lap (n-I) va lap (n) dupe ban bang phuang phap SMAW, yeu cau mdi ban khdng gay anh huong hay de lai bat ki dau vet nao tren be mat phoi ban tai vj tri cd khuyet tat (hinh 4).
Tl-Chieu day chi tiet hdn, R-Khehdddy, f-Mdt phdng ddy; a-Gdc vat
Hinh 3: Thiet ki mdi ghep kieu V don 3.3. Ky thuft tao khuyet tat
Khuyit tat ngam xi cd thi duoc thuc hien bing ky thuat "tao hdc b i y xl" tai mpt vi tri da dinh trudc. Ky thuat nay duoc thuc hien bang each didu chinh gdc dp que han va thay ddi sd lap mdi han k i t hop vdi viec cd y khdng lam sach xi tai hdc xi. Ky thuat tao khuyet tat ngam xi dupe d l nghi nhu sau:
Hinh 4: Ky thugt tgo khuyet tdt ngdm xi 4. THI/C NGHIEM
De kiem nghiem va danh gia cdng nghe tao khuyet tat mdi ban ngam xi da de xuat, 5 thi nghiem [1] che tao chi tiet mau dupe tien hanh cho mdi ghep V dan.
Vat lieu: Chpn la thep cac-bon thap ASTM A36 [13] day 12 mm.
Thilt k l mdi ghep: Duoc thuc hien theo diing tieu chuin AWS va cd kich thudc nhu 6 hinh 5 a.
\ L
^
a) Mdi ghep V don b) Vi tri khuyet tdt du kien Hmh 5: Thiet ke moi ghep kieu V don
vd vi tri khuyet tdt du kien
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Trong thiet ke dy kien tao khuyet tat ngam xi hinh thanh giiia kim loai mdi ban (weld metal) tai lap thii 2 din thir 4 va canh mep vat (hinh 4, 5). Tit ca cac lap ban dupe thuc hien 6 vi tri ban b i n g ( l G ) .
Ky tiiuat ban dupe thuc hien nhu sau:
- Han lap thii nhit su dung GTAW vdi cac thdng s6: May han GTAW Daihen OTC Accutig 300P; Que dip phu AWS ER70S-6 Kiswel 0)3,2 mm; cue tinh DCEN, cuong dp d6ng han 125- 140A.
- Han lop thir 2 bang phuong phap SMAW vdi cac thdng so ban: May han SMAW Hero Power Tech 400A; Que ban AWS E6013-Kiswel 03,2 mm; Cue tinh DCEP; Cuong dp ddng dien ban 125 - 130A. Khi ban cac doan dien day (1) va (2) thi que ban hop vdi canh mep vat khoang 30" theo hinh chieu dimg, nghieng theo hudng han mpt gdc tu 70-80" va cho que ban dao dpng ngang [2, 3]. Khi ban doan ngam xi (tao hdc bay xi) que ban can hop vdi canh mep vat (canh tao xi) mpt goc khoang 0 - 1 5 " theo hinh chilu diing va nghieng theo hudng ban tir 70" - 80" va cho que ban dao dpng ngang vdi tdc dp di chuyen que ban nhanh hon tdc dp ban khi han cac doan diln diy.
L u u y :
+ Khi chuyen tir han doan dien day (1) sang ban doan ngam xi khdng tat hd quang ma chi thay ddi gdc dp que ban (0 - 15") va chii y chi cho mdi ban ngau mpt canh vat ban.
+ Khi chuyen tir han doan ngam xi sang ban doan dien day (2) cung khdng tit hd quang ma chi thay ddi gdc dp que han (30").
+ Go xi lam sach mpt phan xi ban khdi hdc b^y xi sao cho phan xi con lai khdng cao hon mdi ban (hinh 6 va hinh 7).
- Han tir 3 d i n 4 lap d l tao chilu cao ng^m xi vdi chi dp ban tuong tu nhu han lop thii 2.
- Sir dung phuang phap SMAW han cac lap 5 va 6 vdi cac thdng sd: May han SMAW Hero Power Tech 400A, que ban AWS E6013- Kiswel 'I»3,2 mm, cue tinh DCEP, cudng dp d6ng dien ban 125 - 130A. Chii y tai Idp 4 cho que ban dao dpng de dap day hdc b i y xi va tao bd mat moi han bing phang hd trp Idp thir 5.
a) Gdc do que hdn theo hudng nhin doc true moi hdn
b) Gdc do que hdn theo huang nhin ngang Hinh 7: Gdc do khi hdn SMAW Thi nghiem: kiem dinh danh gia cdng nghe de xuit dupe tiln hanh tren 5 chi tilt. Hinh 8 la cac chi tiet cd khuyet tat ngam xi sau khi che tao. Hinh 9 gidi thieu kit qua kilm tra khuyit tat ng^m xi bang phuang phap X-quang, sieu am da chin tii (hinh 10).
IIHMII
Hinh 6: Hdn Idp thir 2 Hinh 8: Cdc chi tiet thi nghiem
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NGHIEN CUfU-TRAO Ddi
Hinh 9: Kiem tra chi tiet cd khuyet tdt ngdm xi . X-quang
Hinh 10: Kiem tra chi tiet cd khuyet tdt ngdm xi bdng sieu dm da chdn tir
Bang 1 cho thay kich thUdc khuyet tat ciia cac chi tiet thi nghiem dupe xac dinh bang phuong phap X-quang va sieu am da chan t^i.
Sy phu hop ve kich cd khuyet tat cd dypc til hai phuong phap va kich thUdc thiet ke (hinh 5b) cho thay rang ky thuat "tao hoc bay xi" si£ dyng philang phap han SMAW cd kha nang lap lai cao va chinh xac de che tao cac chi tiet mSu cd khuyet tat ngam xi. Mat khac, ky thuat sieu am da chan til cd loi the so vdi phuong phap X-quang trong viec xac dinh kich thUdc 2 chieu va vi tri chinh xac cua cac khuyet tat.
Bdng 1: Ket qud do kiem cdc chi tiet thi nghiem
Mau 1 2 3 4 5
'2) Uiel bt
Ngoai quan
X-ijuang: taxm sieu tim: Olymp
Moi lian CO khuyet tat (chieu dai, nun) PP X-quang*"
60 60 70 50 55
t>nCP-160CahinelX-Ra a OmniScnn MX
PP sieu am da chan tu*-'
62x4,6 49x5,5 46x5,7 52x5,9 57x4,2
diaior System
5. KET LUAN
1) Cong nghe ban vdi ky thuat "tao hdc bay xi" sii dung phupng phap ban SMAW da dUpc de xuat de che tao cac chi tiet mau co khuyet tat ngam xi. Khuyet tat ngam xi cd the phat hien dupe bang phuong phap X-quang, nhiing se cho ket qua rd rang va chinh xac hOn khi kiem tra bang phuong phap sieu am da chan tii. Ket qua cho thay rang, cac khuyet tat ngam xi dUpc tao ra tUPng tu nhu cac khuyet tat ty nhi^n.
2) Su phu hpp ve kich thUdc, vi tri cua khuyet tat ngam xi tren cac chi tiet thi nghiem so vdi thiet ke cho thay qui trinh cdng nghe de xuat cd kha nang lap lai cao.
3. Cong nghe de xuat dap ling cac yeu cau theo chuan AWS va cd hieu qua trong viec che tao cac chi tiet mSu co khuyet tat ngam xi phuc vu dao tao va nghien cifu.
Ldi cam dn:
Nhdm tac gia xin chan thanh cam an Cong ty TNHH Giai phap Kiem dinh Viet Nam (VISCO) da ho trp thyc hien nghien ciiu nay.'t*
Ngay nhan bai: 02/4/2014 Ngay phan bien: 09/5/2014 Tai lieu tham khao:
l\]. Phin HieuiGen (2001), PhUdngphap bo tri tlii nghiem vdxCtly so lieu (thSng ki tbUc nghiem). NXB. Nong nghiep.
|2] Trim Van Nien, Tran The San (2001), Thiic hinh ky thua! Han - Gd.
NXB-DaN^ng.
[3| Hoang Tiing (1999). Cam nang hdn. NXB. Khoa hoc Ky thu4l [4] TCVN 4395 (1986), Kiem tra khongphd huy - kiem tra mdi hdn kim loai bdng tia rdnghen vd gamma..
[5] TCVN 1548 1987. Kiem tra khongphd huy moi hdn - Phiidngphdp
[6]. TCVN 165.1988. Kiem tra khongphd huy-Ki6m tra chat iMng moi hdn ong thep bdng phiidngphdp sieu dm
[7]. TCVN 5113 (1990). Kiem tra khdng phd h&y - Cap chat liiOng moi hdn
|8]. TCXDVN 314:2005. Han kim loai - Thuat ngfl va Dinh nghia,
|9] MaitelloConsonni. Chen Fun Wee and Charles Schneider (2011), Paper presented at NDT 2011 - 50th annual conference of the British Institute of Non-Destructive Testing. 13-15 Sepi. Telford, UK
[10], CWB Group - Industry Services (2008), Welding procedure guide, CWB Group.
[ 11 ] ENIQ DOC(95)2 (1998). Development of ENIQ termmology lakuig into account new standards. Glossary of terms used in qualification, EC, Jomt Research Centre, Institute for Advanced Materials, Petten Establishment [12] International Atomic E n e t ^ Agency (2001), Guidebook for the Fabrication of Non-Destructive Testing (NDT) Test Specimens - Training Course Series No, 13. IAEA
[13]. Standard codes AWS D l . l 2010. AWS A3 0, AWS A5 1, AWS AS.18.
[14]. Standard codes ASME 1X2010. ASME B31 8-2010 [15]. World centre for materials joining technology (2006). Welding inspection Rev., T W i Hd.
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