Nghiên cứu xác định độ cứng thép tôi và RAM bằng nhiễu xạ x quang

NGHIEN cflu - TRAO DPi NGHIEN CtfU XAC DINH D p ClJtNG THEP TOI VA RAM BANG NHIEU XA X QUANG DETERMINATION OF HARDNESS OF QUENCHED AND TEMPERED STEEL USING X-RAY DIFFRACTION TS Le Chi CiiOng Tracing Dai hoc SU pham Ky thuat Thanh Ho Chi Minh TOM TAT Do cdng Id mgt chi tieu cO tinh quan trgng cda vdt lieu ca khi, vd thudng dUdc xdc dinh b phuang phdp phd huy truyen thong dung mui dam Bdi bdo ndy, trinh bdy nghien cdu moi lien he g cdng cua thep C50 toi-ram d nhieu nhiet va be rgng cua dudng nhiiu xa, the hien thong qua d cua dudng cong Gauss Ket qud cho thdy mgt moi lien he tuyen gida be rgng trung binh cua dddn xa, td dd md khd ndng xdc dinh dg cdng cda vat lieu tinh the bang phddng phdp nhieu xa X quan "Vii khoa; Nhiiu xa X quang, cdng, thep toi, be rgng trung binh, dudng cgng Gauss ABSTRACT The hardness is a significant issue of mechanical materials, and usually determined by destructive methods using pointers This paper studied on the relation between the hardness of qu and temperred steel C50 and the broadness of the diffraction line, represented by the width of the G curve method The experimental result has determined a proportional relation to the line half-wid showing a posibility of evaluating the hardness of crystalline materials using X-ray diffraction Keywords: X-ray diffraction Hardness, Quenched Steel, Half-width, Gaussian curve I GIOI THIEU tien hanh tai hien tnJdng {insitu) Dp Cling la kha nang chong lai bien dang deo cue bp, la mot co tinh quan cua vat lieu CO khi, diioc xac dinh bang each miJc dp chong lai bien dang miii dam co dang chuan len be mat vat lieu [1,2] Nhin chung, cac philong phap xac dinh dp cilng tren (Brinel, Vicker, Rockwell) deu la cac phuong phap pha huy, giiy hii hai be mat chi tiet may Mot so trudng hpp khong the Phuong phap nhieu xa tia X dxiac sii dung de xac dinh iJng suat dii, tinh ilng suat moi, A dinh pha tinh the, ma khong pha huy chi tiel mau Nhieu nghien cilu trildc day cho thay, bit ciS sU thay d6i nao cau true cia vat lieu tint the (nhii bien dang deo, xvl ly nhiet, qua trulh Ulf kim hoa, ) deu dan den mpt anh hiidng d&c^ dac trUng cua dUdng nhilu xa X quang, bao g^rt I Q TAP CHi CO KHi V I £ T NAM • So (Thang nam 2013) NGHIEN C U T U - T R A O D O I ba thdng so quan trpng Id vi tri dinh nhieu xa, hinh dang vd dp ldn cua dfldng nhieu xa, [3,4,5] Bdi bao nay, nham xac dinh mdi lien he sfl thay ddi pha cua thep C50 tdi vd ram, the hien qua dp cflng, vdi be rpng trung binh cua dudng nhieu xa tia X, tU dd de xuat phflong phdp dp cflng cho cdc vat lieu tinh the dp chinh xdc cao hon cdc phflong phdp khde vd cd the tinh dflpc dp lap lai {reproducibility), dac biet la phflpng phdp sd dUpc sfl dung rat thdng dung hien tren todn the gidi Do dd, bdi nghien cUu xdc dinh be rdng trung binh cua thep tdi va ram dung phUPng phdp dUdng cong Gauss Mdt each tdng qudt, ham mat dp xdc xuat ngau nhien (Gauss) cd cdng thflc BE RQNG Dl/CJNG NHIEU XA BANG PHl/CfNG P H A P GAUSS gix) = -T^l^-M)' (1) •Jl/ra Cd hai loai dp rdng dfldng nhieu xa Id: - Dp rpng Laue {integral breadth ^) Id ty so cfla cUdng dd tich phan vd cUdng dp nhieu xa toi da Tuy nhien, cUdng dp tich phdn phu thupc rat manh vdo pham vi gdc nhilu xa, nen cd dp chinh xdc rat thap Trong [t la gid tri (mean) hdm Gauss, vd o la sai lech chuan, cho thay mflc dp phdn tdn cua hdm TrUdng hpp chuyen true tung ve gid trj p, g(x) - Ae ' - Dp rdng Scherrer {Full Width at Half Maximum-FWHM gpi tat Id be rdng trung binh) Id dp rpng cua dUdng nhieu xa tai vi tri 50% cua chi^u cao cUdng dp cflc dai (sau dd hieu chinh nln) (2) Trong cac tham so A (ddc trUng cho gid tri cUc dai) vd o dac trflng cho dp md rdng cua dfldng nhieu xa, Ian Iflpt dflpc xdc dinh bdng: (3) (4) a) Do rgng Laue D f rfnft MiHivrrvwiu&a^ Lay logarithm cdng thflc (1) tai tflng diem dfl lieu thflc nghiem ta bien doi hdm Gauss thdnh mdt ham bdc hai (parabola) = h\ly^ = - a InA x(5) Trong dd 1^ la sd nghich ddo cua he sd Lorentz-phan cflc vd hap thu LPA 17I nham hieu chinh dat dflpc cfldng dp nhieu xa chinh xdc b) Do rgng Scherrer Hinh 1: Do rgng dUdng nhiiu xa Cd nhieu phflong phdp cd the xdc dinh bl rpng trung binh nhU phUPng phdp be rdng trung binh (tinh toan tfl ba diem dfl lieu xuang quanh vi tri trung binh), phflpng phdp Gauss vd phupng phdp parabola (npi suy tU cdc diem thUc nghi?m bdng cdc dUdng cong tUPng flng) Tuy nhien, phUong phdp Gauss dflpc xdc dinh Id cd Hinh 2- Dudng nhieu xaX quang dugi not >,u^ bdng dudng cong Gauss TAP C H i C O KHi VIET NAM Sd (Thang nam 2013) NGHIEN CUU - TRAO DPi Tham so a dflpc xdc dinh bdng phflong phdp binh phflong nhd nhat tfl n diem dfl lieu thflc nghiem (x^y) (i=l n) each deu bUdc nhieu xa c, dUpc xac dinh bang [5] Trong do: dd mUdi mau dflpc tdi nfldc d nhiet 830''C Sau mau sd 10 mdu dUpc ram d nhiet dp 250^ 300", 350°, 400", 450°, 500", 550" 600", 650" thdi gian 45 phut Cudi cung todn bp mau dflpc mdi bang giay nhdm be mat vd ddnh bdng tren may mdi Ii tam vdi vai nhung Dieu kien bdng nhieu xa dflpc cho Bang Ddng thdi de ddi chieu vdi phflpng phdp nhieu xa, cdc mau dflpc dp ciing ba Ian theo thang HRC vd lay gia tri trung binh Bdng 1: Dieu kien thi nghiem bdng nhiiu xa X quang Z^, Z^? Z^' (7) I.K z^,' I.-: Trien khai cong thUc (6) va (7), ta co: >?(«'-l)(«''-4) -iO'^T,hl,y, (8) Phupng phap Kieu O CO dinh ri Mat nhieu xa (211) mang lap phUdng the tdm Gdc Bragg 29 = 82.3" Pham vi gdc nhilu xa 80-85" Bfldc nhilu xa 0.04" Trong do: T = 12tf -n'- + 1; t = i-(n-l)/2 Thdi gian Hoanh dp tai chieu cao 50% cUdng dp nhieu xa Ong phdng cao nhat la; Tam lpc 5s CuKa, budc song l.SA" Tdm Ni Do dd, be rdng trung binh dflpc tinh tfl phflpng phap Gauss la: = 2,360- (10) Mat khac, be rdng tich phdn phflpng phdp dfldng cong Gauss dflpc dflpc tinh bdng: Hinh 3: Ihiet bi nhilu xa Panalitical X'Pert KET QUA VA KHAO SAT \si^)dr -^/2^(T-2,5I(T (11) Hinh cho thay du6ng nhieu xa X quang cua mau thep toi, dupc npi suy bang dUcing cong Gauss TU cac tham so A va a cua ham Gauss, sai Trong dd, tdng tich phan cua hdm mdt lech chuan cua ham Gauss a va be rpng B ciia ham Gauss duac xac dinh tU cac cong thilc (8) va (10), ]g(x)dx= va dupc the hien Bang Mat khac dp alng trung binh HRC cua ba lan ciia cac mau thep ciing dupc trinh bay Bang Tii gia tri tinh TRiNH TLT THi NGHIEM toan dupc ta thay be rpng trung binh giam dan til mau thep toi den ram nhiet dp cao 650°C v4 nhJ Mfldi mdt mau thep C50 dflpc gia cdng nhat la mau thep nguyen thuy khong qua nhift bdng phay dat kich thflde 10 x 10 x 20 mm, luyen A A TAP CHi CO KHi VIET NAM V SP (Thang nam 2013) NGHIEN C U T U - T R A O D O I Hinh bieu dien mdi quan he gifla dp cflng HRC va be rdng cua dfldng nhieu xa, bao gdm b l rpng trung binh B, vd be rpng tich phan Bj dupc xdc dinh tii cong thiic (10) va (11) Cdc diem dfl lieu dupc phan bd tfldng doi deu vd dUpc ndi suy tuyen tinh bdng phUong phap binh phuong nhd nhat PhUPng trinh moi quan he HRC-B dflpc xdc dinh tfl thflc nghiem la: HRC =101,458-39,89 (12) Hinh 4: DUdng nhiiu xq cua mdu thep toi dUdc ngi suy bdng hdm Gauss Bdng 2: Kit qud tinh todn be rgng trung binh vd cdng Rockwell cua cdc mdu thep Mau toi va ram ("C) Dp Cling HRC T6i 250 300 350 400 58.0 53.2 52.8 51.2 450 500 550 600 650 Khong nhiet luyen 46.3 39.8 38.5 31.5 26.5 21.5 18.7 Gia tri cUc dai A (phptpns) 332.76 342.62 384.61 406.37 Tham sp a Be rpng trung binh 1.1282 1.1626 1.2003 1.2339 1.2403 1.2802 0.3928 0.3699 0.3470 0.3284 0.3250 0.3051 0.2903 0.2788 0.2593 0.2381 0.927 0.873 0.819 0.775 0.767 0.720 0.685 0.658 0.612 0.562 0.551 Be rong tich phanB/O) /(«) 419.50 408.25 456.57 481.59 512.00 1,3125 1.3391 1.3886 1.4490 1.4634 532.80 589.84 10 Sai lech chuan o ( ) 20 30 0.2335 40 50 0.986 0.928 0,871 0.824 0.816 0.766 0.729 0.700 0.651 0.598 0.586 60 B^ rOng duong nhieii x?, deg Hinh 5: Moi quan hi giUa cdng Rockwell vd bi rgng dUdng nhieu xq TAP C H i c a KHi V I £ T N A M ••• Sd (Thang ndm 2013) NGHIEN CUU - TRAO DPi KET LUAN Bai bao trinh bay nghien cUu da xac dinh be rpng cua dudng nhieu xa X quang bang phiiong phap npi suy dUdng cong Gauss Ket qua thUc nghiem cho cac m l u thep C50 t6i va ram chp thay cUng va be rpng trung binh co moi lien he tuyen tinh nhu cong thilc (12), cho thay nhiSu xa X quang CO kha nang xac dinh dp cUng cua thep toi bang phuong phap khong pha h u y Day la mpt ket qua thii vi va CP y nghia ldn viec Ung dung cac phuong phap khong pha huy de danh gia co tmh cua vat lieu CO Tuy nhien, de co the ap dung rpng rai chp nhieu loai vat Ueu, can md rpng danh gia va kiem nghiem phuang phap cho nhieu loai vat lieu, lap he thong dii lieu nhilu xa cho m6i nhom vat lieu nhieu trang thai khac nhu nhiet luyen, bien dang deo, hop kim hoa, khac • Ngay nhan bai: 05/3/2013 Ngay phan bien: 05/4/2013 NgUtii phan bi6n: PGS.TS Dang Thien Ngon, TrUdng Dai hoc SU pham Ky thuat TP Ho Chi Minh Tai lieu tham khao: [ ] Img Shi and C, Richard Liu, Decomposition of Thermal and Mechanical Effects on Microstructure and Hardness of Hard Turned Surfaces, School of Industrial Engineering, Purdue University, West Lafayette, IN 47907, pp, 32-56 [2] Victor Hauk, Structural And Residual Stress Analysic By Nondestructive Methods, Elsevier, 1997, pp 85-111 [3], D.J.Hornbach, et.al., X-ray Diffraction Chacracterization of the Residual Stress and Hardness Distributions, First Int Conf on Induction Hardened Gears and Critical Components, May 15-17, Indianapolis Gear Research Institute, 1995, pp 69-76 [4], Le Chi Cuong, Structural Analysis for Nano Ceria Using Fourier Analysis for X-Ray Diffraction Line, The 2012 International Conference on Green Technology and Sustainable Development, VNU Publishing House, 2012, pp 255-259, [5] Ting Huang, et.al,, Advances in X-Ray Analysis, University of Denver-Department of Engneering and ICPDS-International Center for Diffraction Data, 2005 [6] Kunta, M., X-Ray Stress Measurement By The Gaussian Curve Method, X-Ray Diffraction Studies On The Deformation And Fracture Of Solids, Current Japanese Materials Research, Vol.10, pp 135-151,1993 [7] L C Cuong and M Kurita, Absorption Factor And Influence of LPA Factor On Stress And Diffraction Line Width In X-Ray Stress Measurement With And WUhout Restricsion Of X-Ray Diffraction Area, The Japanese Society for Experimental Mechanics, 2004, pp 7-14 I VP C H i CO KHl VIET NAM V So (Thang nam 2013) ... nghien cUu xdc dinh be rdng trung binh cua thep tdi va ram dung phUPng phdp dUdng cong Gauss Mdt each tdng qudt, ham mat dp xdc xuat ngau nhien (Gauss) cd cdng thflc BE RQNG Dl/CJNG NHIEU XA BANG... Gauss dflpc xdc dinh Id cd Hinh 2- Dudng nhieu xaX quang dugi not >,u^ bdng dudng cong Gauss TAP C H i C O KHi VIET NAM Sd (Thang nam 2013) NGHIEN CUU - TRAO DPi Tham so a dflpc xdc dinh bdng... nhieu xa dflpc cho Bang Ddng thdi de ddi chieu vdi phflpng phdp nhieu xa, cdc mau dflpc dp ciing ba Ian theo thang HRC vd lay gia tri trung binh Bdng 1: Dieu kien thi nghiem bdng nhiiu xa X quang