Nghiên cứu ứng dụng phương pháp siêu âm trong kiểm tra khuyết tật vật liệu kim loại

Tap chi KHOA HOC DHSP TPHCM So 36 nam 2012 NGHIEN CUU ilNG DVNG PHUONG PHAP SIEU AM TRONG KIEM TRA KHUYET TAT VAT LIEU KIM LOAI NGUYEN VAN HUNG' TOM TAT Hien co nhiiu phuang phdp khong phd hiiy (NDT) de kiem tra cdc khuyit tat ben vat lieu kim logi img dl/ng cong nghifp Bdi bdo ndy trinh bdy ling dung ciia phuang phdp sieu dm (UT) vdi viec sir dimg mdy Tokimec de xdc djnh cdc khuyet IQI v,il lieu kim logi nhiim vd thep Kit qud thuc nghiem vdi mdu nhom TC4 (xdc dinh duac khuyit tat) vd mdu thep SA4 (xdc dinh duftc khuyit tdi co so sdnh vdi ket qua xac dinh biing phuang phap chup dnh phiing xa tia-X RT) cho thiiy phuang phdp sieu am rat lien lai vii co ich viec kiim tru khuyit tat vat li(U Nghien cuu ndy rdt co ich cho vi(c ddo tao kt thuat vien vi linh vuc kiim tra khuyit tdt vdt lieu kim loai bdng phuang phdp sieu dm Tie khoa: kiim tra khong pha huy (NDT), ki jm tra bing sieu am (UT), kiSm tra bang chup anh phong xa (RT) ABSTRACT Applied research in ultrasonic methodfor examination of defects in metallic materials There are many methods on none-destructive testing (NDT) for examination of defects in metallic material applied in industry today This paper presents the application of ultrasonic method (UT) with using Tokimec device for determination of defects in metallic materials of aluminum and steel The experimental results with aluminum sample ofTC4 (5 defects were determined) and steel sample ofSA4 (8 defects it ere determined, in comparison with the resuh determined by method of X-ray radiographic testing, RT) show that the ultrasonic method is very convenient and useful for examination of defects in materials This research is very useful to train technicians in the field of examining defects in metallic materials Keywords: non-destructive testing (NDT), ultrasonic testing (UT), radiographic testing (RT) Mff dau Hien tren the giai cung nhu nuoc, phuang phap kiem tra khong pha huy (NDT) dong mgt vai tro quan trgng ki jm tra chit lugng san pham cong nghiep (ung dung rgng rai cac nganh cong nghiep co khi, xay dung, tau ' TS, Trung tam Hgt nhan TPHCM thiiy, hang khong, 16 phan img va nha may di?n hat nhan, ), phuong phap sieu am (UT) co nhieu im viet va bi jn U'u diem cua phucmg phap la co the phat hien cac khuyit tat nho, cho phep kiem tra cac chi tiSt day, co 48 chinh xac cao viec xac dinh vi tri va kich thuac khuyet t^t ciing nhu chieu day vat lieu, va chi can tiep xuc tit mot phta ciia vat lieu Tap chi KHOA HOC DHSP TPHCM Nguyen Vdn Hdng Co sd li thuySt ciia phuong phap la sit dung song sieu am (la mgt dang dao' dpng ca hgc) co dai tin s6 tir 0,5 MHz dSn 10 MHz Song sieu am-dugc phat tit dau do, den mat phan giai giira hai moi truang thi chii yeu se phan xa ngugc tra lai va mgt phan se khuc xa Xung phat ^^3^ Xung khu\ et tgt —^ (phan khuc xa rat nho, nhit la mat phan gioi giiia vat lieu va khong khi, nai co khuyet tat hoJie mat phan each) Mot nguyen li ca ban ciia phuang phap UT di kiem tra vat lieu duac trinh bay tren hinh 1[1,2] Xung da> ^ Vat lieu kiem tra Hinh Mot nguyen li cua phucmg phdp UT kiem tra khuyet tat vat lieu dung de hien thi cac xung phan xa tu day Tuy Iheo dang, huong va vi tri va tir khuyet lat, tu ta co the tinh duac khuyet tai ma nguai ta sii dung loai dau vi tri va kich thuac cua khuyet tat [5] thang (Normal probe) hay dau goc (Angle probe) de phai sdng sieu am Trong phucmg phap UT co mot so kT thual Ihirc nghiem de xac dinh kich Ihuac ciia khuyet tat, nhu sii dung duong cong DAC (Distance Amplitute Correction), bieu dd DCS (Distance Gain Size), giam 20dBhay6dB[l,3] Thirc nghiem 2.1 Thih bi, dung cu thuc nghiem May sieu am va cac dau (dau Ihang va dau goc), mau chuan va mau can kiim tra co tai Trung tam dao lao (Vien Nghien cuu hat nhan) duac sii dung thirc nghiem a) May phat sieu am dang Analog TOKIMEC, Series SM-101 va cac d4u Hinh Cdc loai ddu dd vd mdy sieu dm Nhat Ban san xu§t (hinh 2) Man hinh khuyet tat TOKIMEC CRT (Cathode Ray Tube) cua may dugc S6 36 ndm 2011 Tap chi KHOA HOC DHSP TPHCM b) Mau chuan nhom TCI vit mau kiem tra nhom TC4: Chiing d^ing hinh khoi chir nhgt, co moi h^n dgng chit V viVi ciing kich thudc (16x196x200 mm') nhu chi tren hinh ?> Mau chuan C'."? co cdc khuyet tat nhan tao (co 16 each 12 va mm so v6i be mat phia tren), diing de XB dung dudng cong DAC Duong cong na dugc sir dyng de kiSm tra khuyet tat tron miu TC4 [5] L 1% Si S; s< Ss S^ 200 ^ w Hinh Kich thuac, khuyet tdt nhdn tao, vi tri ddt ddu (tuang dng vai cdc vi tri ddnh so) doi vai mdu chuan TC3 (Hinh tren Id mat nhin tir tren xuong, hinh duai la mat nhin phia ben) c) Mau kiem tra thep SA4: Dang hinh khoi chii nhal, kich thuac 18xl80x200mm^ co cac khuyet tat nhan tao nam a ben Irong khoi mau [5] Mau dugc kiem tra khuyet tat va dugc so sanh voi phuong phap chup anh phong xa tia-X (RT) vai viec sii dyng may Radioflex-200EGM co tai Trung tam dao tao 2.2 Ket qud thuc nghiem Trong thuc nghiem da su dyng hai phuang phap dl xac dinh khuyit tat: phuang phap duang cong DAC va phuong ph^p giam dB Phuang phdp Hudng cong DAC Tren hinh 4, vi tri danh s6 1, 2, va tuomg ung vdi dp sau 3T/4, 5T/4, 7T/4 82 va 1OT/4 (T la be day mau kiem tra) Dai mieng plastic mong len man hinh, dat vi quet dau goc tai S|, dieu chinh niim dc Igi cho bien xung co dp cao WA man hinh (Full Scale Heigh - FSH) Danli dau len man hinh vi tri cua dinh xung Thuc hien lai viec danh dau vi tri dinli xung tren man hinh vdi cac duong S2, S3, S4 S5 Noi cac diem tren lai vdi ta xay di^g dugc dudng cong DAC (Hinh 4) Dudng cong bieu diln bien cua cac xung phan xa tir nhirng khuyet tat CO cung kich thuac nhung nam o cac sau khac Miic dp cao xung (chpn la 80% dp cao man hinh) dupc gpi la mu^ so sanh co ban (Primary Reference Level - PRE) [3, 4] T9P chi KHOA HOC DHSP TPHCM Nguyen Van Hiing DAC for 56,5 S 80 ^^S ^ ^ I 60 Al,45dB Ranee: 100 mm 32 ~ 1 l l l 1 A.Q^ cao mdn hinh Hinh Duang cong thuc nghiem DAC (True tung la cWiiu lay bdng 100%; true hodnh la chieu ddi, tinh bdng cm) Kiem tra mau nhom TC4 Su dung dau goc 56.5", tan s6 MHz de quel kiem tra mau TC4 De dam bao chum tia song am chieu vao mol vung the tich toi da eua \at nham khong bo sol khuyet tat can phai tinh loan qua trinh dich chuyen ciia dau Vai mau TC4 Ihi can xac dinh dudng trung tam L cua moi han, be rpng mu gia cudng cua moi han (W = 28 mm), khoang each mpt buoc quet (S = 48,4 mm) Do do, viing quet ciia dau tren mau la tir S/2 (24,2 mm) din S+W/2 (62,4 mm) Ket qua quet: De phat hien mgi khuyet tat, ta dat dp nhay ciia may cao han miic dp nhay danh gia PRE, b4ng each tang niim lpi (Gain) ciia may Ien dB (tang dp khuech dai cua may len g§p doi) Qua trinh quet phat hien khuyel tai ling vai vi iri ciia dau do, co khoang each lu bi tri ciia dau den duang trung tam da dugc nhu Iren hinh (3 khuyet tat cho xung tren man hinh CRT co bien dp vugt qua dudng cong DAC) -7^ Viing hin Hinh Viing quel cua ddu dd vd vi tri dau ung vdi cdc khuyet tatA.BvaC (Hinh tren Id mat nhin tic tren xudng, hinh dual la mat nhin phia ben) 83 Tap chi KHOA HQC DHSP TPHCM So 36 nam 2012 Giam niim dg Igi cua may di dB de quay ve mire dp nhay danh gia thi thay co khuyet tat co bien dp xung vin c6n vu0 qua dutmg cong DAC, chimg to khuyjt lat CO kich thuac 16n hon khuyjt tjt nhan tjo miu chuan nen khuyjt tat phai bj loai bo Vj tri vk so d6 cac khuyet t^t niy dugc xac djnh nhu tren hinh va hinh ^ Di/6nii irunji ii'im mAi liiin .S/2+W/2 ZL Hinh Vj tri cdc khuyit tdt KTI (fiinh tren) va KT2 (hinh duai) Hinh Vi tri vd kich thuac cdc khuyet tdt mdu kiem tra nhom TC4 (Hinh tren la mat nhin tic tren xuong, hinh du&i Id mgt nhin phia ben) 84 Tap chi KHOA HOC OHSP TPHCM Kiem tra mdu Ihep SA4 Sir dung diu thing va phuang phap giam dB &i xac dinh kich thuoc khuyet tat nhu sau: Xac dinh vj tri diu cho thu dugc bien xung cue dai tir khuyet tat; dieu chinh bien xung khuySt tat d6n mgt dg cao thich hgp (ching ban bing 80% FSH): djch chuySn dau sang mpt phia cho bien dg ciia xung khuyet tat giam xu6ng mgt nira tuc la bien xung chi bing 40% FSH Ghi lai vi tri ciia tam diu tren bi mat ciia miu kiem tra; djch chuy& diu 'fei D< Nguyin Van Hung theo chieu ngugc lai, bien xung khuyet tat lai tang din len, dat gia trj eye dai roi lai giam xudng, cho djn bien dg xung bing 40% FSH thi dimg Iji Ghi lai vi tri moi cua diu a tren mau Khoang each giua diSm danh diu o tren chinh la kich thuoc ciia khuySt tat theo phucmg Tir xk: dinh dugc vj tri va kich thudc cac khuyet tat mau kiem tra SA4 (hinh 8) Kft qua dugc so sanh vol kk qua sir dung phuong phap RT, dugc neu bang [4] ^"^KTZJL.IU^ Hinh Vi tri vd kich thuac cdc khuyet tdt mdu kiem tra SA4 (Hinh tren Id mat nhin tir tren xuong, hinh duai la mat nhin phia ben) Bdng So sdnh ket qud ditng phuong phdp sieu dm (UT) vai chup dnh phdng xa tia-X (RT) Diem UT (mm) RT (mm) Sai so (%) 20,0 19,0 5,0 72,0 70,0 2,8 31,0 34,0 8,8 30,0 32,0 6,3 KSt luan Nhu vay, sii dung phuang phap UT CO the xac djnh dugc cac khuyet tat cac vat lieu: d6i vai mau nhom TC4 xac djnh dugc khuyet tat (trong co 10 81,0 26,4 - 11,0 15,0 2,0 12,0 15,0 80,0 26,0 1,0 1,5 1,2 - 8,3 0,0 khuyet tat qua to va bj loai bo theo tieu chuan chat lugng ve khuyet t^t) va mau thep SA4 x4c dinh dugc khuyfa tat (rieng di8m va thi chi phat hien dugc khuyit tat nhung khong xac djnh 85 Tap chi KHOA HQC DHSP TPHCM dugc kich thudc ciia chiing dieu ki?n A12 = mm, \6\ k Xk bu6c s6ng sieu Sm ciia d4u ph^t) Tren co s6 dya theo cac tieu chuan dinh gi^ chat lugng san pham de dua ket lu^n san pham d6 co dugc chap nhan khong hay phai bj logi bo ho^c phai gia cong Igi Ve ket qud ciia hai phuong ph^p kh^ giong v6i sai so pham vi cho phep (nho han 9%) Phuang phap RT c6 uu diem la co the xac dinh dupc dudng kinh ciia cdc 16 khuyet tat, c6n phuang phdp UT lai co the xdc dinh chinh xac vj tri khuyit tat cung nhu chieu day vat li|u Tom lai, tren thuc tl nhilu trudng hgp can co sir bo sung ciia cdc phuang phdp khdc de dat kel qua kiem tra cao han Ngoai ra, kit qua nghien ciiu ndy c6 the giiip ich cho cong tdc ddo tao kT ihuat vien ve kiem tra khuyel tat vat li?u kim loai ling dung cong nghiep [1,3, 4] TAILipU IIIAMKHAO Cong ti Ung dyng va phat trien cong nghe "NHAD" (2002), Phuang phdp sieu dm kiem tra vdt lieu - cdp 11 (Bdn d'fch tir nguyen bdn IAEA), Vien Nang lugng nguyen tu Viet Nam Truang Quang NghTa (1997), Gido trinh ki thudt kiem tra khong hiiy thi bdng phucmg phdp sieu dm, Truang Dai hpc Khoa hpc Tu nhien TP.I ICM, IAEA (1988), Ultrasonic testing of materials at level 2, IAEA-TECDOC-462, Vienna, Austria I.I.W (1977), Handbook on the ultrasonic examination of Welds The Welding Institute, England Tokimec Inc (2006), Portable ultrasonic flaw detector - Operation manual Series SMlOlJapan (Ng^y Tda so$n nh$n du^ 86 So 36 nam 2012 bdi 27-12-2011 ngdy chSp nh$n dSng- 24-4-2012) ... li ca ban ciia phuang phap UT di kiem tra vat lieu duac trinh bay tren hinh 1[1,2] Xung da> ^ Vat lieu kiem tra Hinh Mot nguyen li cua phucmg phdp UT kiem tra khuyet tat vat lieu dung de hien... phdp khdc de dat kel qua kiem tra cao han Ngoai ra, kit qua nghien ciiu ndy c6 the giiip ich cho cong tdc ddo tao kT ihuat vien ve kiem tra khuyel tat vat li?u kim loai ling dung cong nghiep... (1988), Ultrasonic testing of materials at level 2, IAEA-TECDOC-462, Vienna, Austria I.I.W (1977), Handbook on the ultrasonic examination of Welds The Welding Institute, England Tokimec Inc (2006),