Xác định sự phân bố ứng suất dư theo chiều sâu bằng phương pháp cắt lớp

NGHISN cCru-TRAO D I XAC DINH SU PHAN B UNG S U A T DU THEO CHI^U SAU BANG PHUONG PHAP CAT LOP DETERMINATION OF IN-DEPTH RESIDUAL STRESS DISTRIBUTION BY LAYER REMOVAL METHOD Tran Minh Tiln, Le Chi Cmmg Truong Dai hoc Su phjm Ky thuat TP H6 Chi Minh T6M TAT IJ'ng sudt du tren bi mdi vgt lieu tinh thi cd Ihi gay bien dgng hope phd huy vgt ligu; do, vigc xde dinh img sudt du cd vai trd quan trgng qud trinh xu ly vd cdi thign dieu kign ldm vigc cua chi tiit mdy Nghien cieu ndy se gi&i thigu phuang phdp cdt l&p de xdc djnh sv ptid bd img sudt cbt qua chiiu ddy cita mdu thu Phuang phdp thich hpp dilng decdt l&p md khong sin them img suat du m&i tren bi mat mau thie Id ddnh bdng dign hda Sau cat l&p, Ong sudt dit bi mgt mdu dupc bdng nhiiu xg X-quang Vigc xdc dinh sit phdn bd irng sudt du theo ehieu sdu duge thuc hign Iren mau Ihep €45 Ket qud cho thdy, ung sudt du phdn bd khdng dong nhdt theo chieu sdu cua mdu thie Tir kh6a: f/ng sudt du, phucmg phdp cdt l&p, nhieu xg X-quang, ddnh bdng dign hda ABSTRACT Residual stress in the surface layer of crystalline materials may cause deformation or damage o materials, determination of residual stress plays an important role in treatment and improvemen process of the working conditions of machine components This paper will present the techniqu using layer removal method lo determine the residual stress distribution through the thickness ofi specimen The appropriate method uses for removing layer that does not introduce Ihe new residu stress in the surface layer ofihe specimen is the eleetropolishing technique Ttie residual stress the surface ofihe specimen is measured by X-ray diffraction for removing layer Determination o the in-depth residual stress distribution was carried out on steel €45 specimen The result shows that the residual stress distribution is the inhomogeneous in the direction of the thickness Keywords: Residual stress Layer removal method X-ray diffraction, Eleetropolishing GIOI THIfU Ung suat du U Uang thai ung suit ton tai phan Ion ben vat li^u khong c6 tac dung cua ngojii luc lfng suit du co thi phit sinh hau hit qua trinh san xuit nhu xii ly nhi?t, hojc gia cong co ITng suit du la nguyen nhan gay phd hiiy chi tilt vJ c6 inh hudng tnre tilp din dp bin moi cua chi till, Nhilu phuong phap da dugc phit triln dl xic dinh umg suit du, chiing dugc chia lam ISSN 0866-7056 TAP CHf CO KHl V I £ T NAM, S6 nam 2016 NGHIEN CCrU-TRAO D O I hai lo^i Phuang phap phi huy (destructive techniques DT), bao gom: Phuang phap khoan lo, phuang phip vong loi, phuong phip cit lop va phuong phip cSt tilt dien Phuong phip khong phi huy (nondestructive techniques NDT), bao gom: Phuang phap nhilu xa X-quang (XRD), nhilu xa Neutron, phuang phip sieu am va phuong phip dien tit [2-3] U'ng suit du phan bl ben vat lieu c6 anh huang den tinh chat va cuong mon ciia chi tiet may, do, viec xic dinh ling suit du theo chieu sau dong vai tro quan trpng vi^ cii thi$n dilu ki?n lam viec cua chi tilt Tiong trudng hpp nay, phuang phip cit lap dupc kit hpp vcri nhilu xa X-quang dl xic dinh chinh xic su phan bl iing suit du theo chilu s^u ciia v$t li^u Phuong phip nhilu xa X-quang li phuang phip khong phi huy ciu tnic vjt li$u, cho ket qui chinh xic vl ting suit du vi kha ning tu d$ng h6a de dang, d6 dupc ling dyng tren nhieu loai vit li?u khic Tuy nhien, phuang phip c6n gip han chl truong hpp xic djnh trang thii iing suit du phin bl theo chilu day cua vit li$u, vi ning xuyen thiu cua tia X ky thuit vjt lifu li tuong dli nhd (khoing vii micrd) Vi$c xic djnh va lu6ng iing suit du theo chilu siu ddi hoi phii cit timg lop bl m§t tii mau thii, vi viy phuong phip cit lop la phuong phap thuong dupc iing dung Phucmg phip cat ldp la phuang phip don gian, dl ding xic djnh ling suit du theo chilu siu tii bl mit raau bing cich liy di timg ldp vit li$u mong Vdi phucmg phip cit lop bing cic phucmg phip CO khi, hojc phucmg phip gia cong bing tia lira di?n (electro-discharge machining - EDM) dupc sir dung de cit timg ldp vit lieu cua miu thit se sinh them img suit du mdi nhiet dp cao ttong qui trinh gia cong, tit dd lam thay dli ttirdng iing suit ban dau ciia bl rait [9] Phuang phip cit lap bing cong nghe dinh bong dien hoa la mot nhung phuang phip thich hop nhit, vi phuang phip niy dung de lay di timg lop vit lieu tu miu thii ma khong sinh them bit Cli mpt phin ung suit du moi tai be mat mau va CO the dat dirpc dp bong cao [6,10,12] Nghien ciiu niy da irng dung phuang phip cit lop bing danh bong di^n hoa va ket hpp ling stmt du bing nhieu xa X-quang de xic dinh su phan bo ling suit du theo chieu sau ciia vat lieu XAC BINH iTNG SUAT DlT B A N G PHU'ONG P H A P N H I E U XA X-QUANG vACATLdP 2.1 Dinh bing difn h6a Dinh bdng di?n hda la m0t nhGng phuong phip ciia dinh bdng kim loai va hpp kim, theo dd, lop vat li?u dupc liy di tir be mit bing cich ndi mau thu vdi anot bl di^n phin (hinh 1) Dinh bdng dien hda cd thi dupc irng dungtt-enhiu het cic chi tilt cd hinh d?ing va kich thudc khic [5] ^ ^ ^ Hinh Sa ddnh bdng dipn hda: t) Dung dfch danh bong; 2) Caidi 3) Anoi 4) Nguon ISSN 0866-7056 TAP C H ! CO KHl V I £ T NAM Sd nam www.coichivietnam.vn 2016 NGHieN curu-TRAO OOl Quy Dinh dinh bdng dien hoa gdm budc: - Chuin bi: Loai bd diu, ma, oxit hoac cic tap chit khic bira tren bl mit miu mi chiing cd the lim giim chit lupng hoic gay su khong ddng nhat cho dinh bdng dien hda - Dinh bdng di?n hda: Thuc hien dinh bdng bl mit hoic tien hanh liy di mpt ldp vat lifu de thu dupc dp diy mong mudn Trong dd: J, li budc sdng tia X, e 14 gdc Bragg, dyj li khoang cich tinh thi ciia mit phing nhilu x;! (hkl) Khi xuat bifn iing suit du ti^n Idp bl mit thi khoing cich d^^ giila cic mit nguyen tii sS thay ddi so vdri khoang cich ban dau d^ Bing vifc tinh toin vj tri dinh ctia dudng nhieu x^ thi biln d ^ g cua mau thii dupc xic dinh thong qua khoing cich d^^ Tit biln dang, ta cd thi xic dinh dupc uong suit du dl ding thdng qua moi quan hf iing suit biln d^g theo phuong trinh sau: - Xu ly sau dinh bdng: Muc dich cua xu ly sau danh bdng li de xu ly cic hda chat cdn sdt l^i tten be mit va lam khd bl mit nham phye vy cho quy trinh iing suit du E (cr,, cos^