(1) J = DC. Vol.31 No Journal of Chinese Society for Corrosion and Protection Jun Æ ¼ : TG457 Ó«Ç : A ¼ :

Transcription

1 31 3 ¾ Ðß Vol.31 No Journal of Chinese Society for Corrosion and Protection Jun ÐÂÐ ² λ (ƽÀ«ÔÞß ÆÀÍÞ Æ½ Ø «Þ : µ¹í Ë»Ó¹Í ¹ Á Ý Ç µ¹í ¹ ³»ÝÄĐ¼Ëà ¹ ÎÝ ÏÂۻݼËà м ¹ Î ÝĐ½³ ² µ ½ ÅÀ Í µ Ñ ßĐ Á µ Á ÔĐ Î Ô Đ«Õ Đ Á Å ¼Á ĐËÃ Đ± Û Æ Á ½«Õ ¼Á ĐËÃÂÐ ³ ÂÛ ³Đ¼ ½ ÏÂÛ»Ý ³Đ¼ ĐÅÅ ³Đ¼ ÆÔ½ÏÂÛ»Ý Đ¼ «Õ Ø ³¼ Ô Ê ³ ÂÛ ¼ËÃб ¹»Æ Õ Đ ¼   : ¼ËÃ Æ ¼ : TG457 Ó«Ç : A ¼ : ÌÝ Æ Ê Û ÎÌ ¼ Ù ¹ ¹ Í ĐÛ ±Æ ¼ ±Æ Ô ĐÆ Ï Ì ¼ ±Æ Ù» Û» ÑÑ Æ Ð Ë [1] ÅÅ Æ ¼ È Đµ» ½ ÔÓ» º Ü ÝÔ Òº»» ÔÚ» Ó Ú Ð» ÒÞ«Öµ Í ÄÜ [2 4] ³»À ÊÂĐ ¾ÍÜ» ÑĐÙ»» Ê Â ÌÇ [4]» ÀÏ Đ Ñ»Ê [5,6] À Æ Ì ÀÏÓ ¾ ÏÈ [7 9] ¼ ¾»À Ê Рл Ü» Ï Ò Ä Ë : ÙÉ : ØÕ º Þ (06-D-035 Á Ò Ú Â È Ý Å ÔÞ (BM ØÑ : ½ Å Å1986 Ź ÅĐ ² Ü Ð ½ Ò Ü : Ä Å gongjm@hjut.edu.cn ÀÏ ¾ Å [10] Ø Ó Í̾ À¼» Æ À Ú¼ Ú Ö Æ¾»Ê Šµå ± Æ Û¼Ó ÐÐ ¼¹ ÀϾ Ô ÖÓ ÅÔ Ð Ó ÅÔ Ü Ñ Ç Ñ Ë Ä»Ú»»À ³ Ê ÂÔ ² ÅÔ Ð Ü»À Û ÊÂÁ ³ ÄÓ [11 13] Ó ¹¹Î ÀÁÚ¾»ÊÂ Æ ÁÚ¾ÅÔ»ÊÂ ß Ï É ¼ Ì ABAQUS Æ Ì ¾ ¾ÍÜ ² Á ¾»ÊÂ Ì Ì Æ ºÜ»ÊÂ Æ Ã Ã Æ» Đ ¾ÍÜ 2 Ã Å Ï ÀÆ Àµ ÒÝ ² ÁÚÅÔ Ð»ÊÂ Æ±Ì J = DC µ = DC (µ RT RT 0 + RT ln CKS (1

2 3 ¼ : ¼Ëà Íб 203 K S ³ Ù σ h ε p È [14] «( VH K S = K Sε (ε p exp RT σ h (2 Ö (1 { [ ( VH σ h J = D(ε p, T C C T RT + TK ]} Sε(εp,T K Sε (ε p, T»ÀÊÂ Ì ÐÞ Ø Ü t (2 (3 = divj (4 (3 Ö (4 ¼ÁÚ { D (ε p C t = [D (ε p C] [ VH σ h RT + K Sε (ε p K Sε (ε p ]} (5 Å À¼Áڻʠ(5 ÆÒ ¾«Fick Ü ¼ÁÚ Ê (5 ÆÒ Å ºÜʱ̫( t = D C V HC RT σ h ÆÞ D» ÊÂÁ m 2 /s σ h Đ σ h = (σ 11 + σ 22 + σ 33 /3 MPa ε p ÅÔ V H»À Å Hirth [15] V H = m 3 /mol R Å J/(mol K T K 3 ³ à ŠÖÅ Ñ 3.1 Õ ÈÚ µ¾ ÙÛ X ÊÎ Ê ± Ä ¾ ¼ Æ ¼ Ì Đ² À ÓÎ Ï Ê ºÒÛ Ó [16] º Ⱦ Ô Í ± ƾ ºÒ Ñ ± Ó Æ Ù X ÊÎ Ê ¾ Ö ± Í ± ÔÅÉ Í± Ô [17,18] «Æ ±Æ 1 ÀÍÆ Ã Æ ÏÅÔ Ð Ã ³ÒÚ Å¾ ß Æ Ú ÆË Ç ÎºÒ ß Æ Ì Ì 12 mm Æ Ì 10 mm Æ 3.5 mm Í 7.68 ¼ Æ Ü 120 mm ÁÚÞ±Æ ÊÔ Ê Ò ÙÔ Ò 600 GPa Æ ³ Ì ¾Ñ 2 ÅÑ 30( 600 ( CAX4R 3.2 ÄÆ ÒÝË (mass% : C 0.85 Mn 0.60 Si 0.26 P 1 S 30 È ÈÁ ¼ J.Toribio [19] ÍÌ ± Ramberg-Osgood ±Ì ε = σ/e + σ(a/p n, P=2100 MPa n=4.9 ÍÆ Ô «ÀÍ σ b =1151 MPa ¼ σ s =600 MPa Ó E=199 GPa º ν=0.3 À Æ Ã Æ ¼ÁÚ ÆÜ Ô Á ÚÞÈÖ Á Þ É À 250 à ǼÁÚÅ ÀÏ Ò Ô Á Õ Ð Å ABAQUS Ì ÍÆ Ì ÆÌÙ» ÆË µ À Í Ë ÍÆ (Ë 2 m/s Æ Ð Ð Ö Æ Í ÆË ÀÅ À Ì Å Á À Fig.1 Schematic diagram of cold drawing process (unit:mm Fig.2 Two-dimensional axi-symmetric FE model and meshing

3 204 Ͻ ³ Ý 31 Ë Atienza [17] Í ± Å Á Ë À ¾ à ¼Ó Å Coulomb Å Å Á 3 Ú Í Æ ¼ Ú» À¾ 4 Ã Å Ò ÏÊ 4.1 Í Õ Ì Ñ ÅÖ Å Ï ±Ì ±Ì ±Ì ĐÏ µ ÂÒ ±ÌÏÖ Í Æ ¾ Æ Ð ¾ ϼ Ç Ê ÀÐгà (5 ( D t = r r + C ( D 2 r 2 + D C D r r + D r ( VH σ RT r + 1 K [ Sε VH DC K Sε r RT 1 ( 2 K Sε K Sε r 2 + K Sε r ( 2 σ r 2 + σ r 2 ] ( 1 K Sε K Sε r + (6 Ó Ê ßÅÔ»ÊÂÁ ³ ¼ Ë É±Æ ¼² ±  V.Kharin [20] Àܱ ± Ü Æ Ã¼ à «D (ε p = D 0 exp( ηε p (7 K Sε (ε p = 1 + βε p (8 η = 2.9; β = 4; D 0 à ( Æ»À ÊÂÁ m 2 /s (6 σ h ε p r r r t t = C i,j+1 C i,j t r = C i+1,j C i 1,j 2 r (9 (10 2 C r 2 = C i+1,j + C i 1,j 2C i,j ( r 2 (11 σ h r = σ h i+1 σ hi 1 2 r (12 2 σ h r 2 = σ h i+1 + σ hi 1 2σ hi ( r 2 (13 ε p r = ε p i+1 ε pi 1 2 r (14 2 ε p r 2 = ε p i+1 + ε pi 1 2ε pi ( r 2 (15 σ h ε p Í Ì Æ± Þ (7 (15 Ö (6 ± µ Ä Åû» ¾ ¼ ÅÖ À ºº Ì ÀÏ É ¼ ÄÓ ±Ì (6 ØÐÞ Ô [21] «t r ½»À ÊÂÑ» Ç Ì S(r = R 0 R 0 ÍÆ»µ Ó Ë»ÒÝÐÏ À«Ã Ã Ó Ë» C 0 eq ÃÀ Ãà (2» C S ( C S = Ceq 0 K VH Sε (ε p (R 0 exp RT σ (R 0 µ C (r = R 0, t > 0 = C S (16 «Ó ¼» à 5 ¹ Æ C (0 r R 0, t = 0 = 0 ( Á Õ ÀÍÆ Ì ¾ 3 Æ Ì Đ Æ±ß ¾ 3 ³ Ù Path 1 ¾ ¾ÍÜ 4 4 Ä ¾ Ñ Á à À È Ð À» È Í ¾»Íß Å ÑÔ ßÓ ßÓ; Ò 609 MPa ßÓо Ò MPa 4 Å ¾ ¾ Ð Ê [17,18] ± 5 Ù Path 1 ¾ Đ ÅÔ ¾¾É Ä ÅÔ ÏÚÓ À Ë Ó ÅÔ Ð Ü É±Æ Ò Ä»Ë»À ÊÂÔ

4 3 ¼ : ¼Ëà Íб 205 À 4 5 Ô Æ Ì (axial stress-drawing Đ (hydrostatic stress-drawing ¾ÍÜ ÆÀ ÍÆ Ì ¼¹ÎÚ Æ Å Ð ÔÎÚ ÍÆ Đ 4 Ò 1130 MPa À Ï À ¼ Ì Đ Î» ÍÆ Ì ÀÏ º»À Ð Ü ÀÍ Æ Ï Ñ [22] Ä º» Ð ³Ò ÀÍÆ Ì Ï» Ñ 5.2 Û ß± Í º Đ Ü¼ÆÞ (6 (15 µ (16 Đ (17»ÊÂ Ì ÌÙ Áڻʻ ¾ 6 Ä Ö Ä»Î Í Ï Ó Fig.3 Axial stresses distribution in the wire during/after Stress /MPa cold drawing process Radial stress Axial stress Hoop stress Axial stress-drawing Fig.4 Plot of distributions of the residual stresses in cold Hydrostatic stress /MPa drawn steel wire Hydrostatic stress s h Hydrostatic stress-drawing Plastic strain p Plastic strain p Fig.5 Distributions of the residual hydrostatic stress and plastic strain in cold drawn wire À 2000 h ¼ ¼ 7 ² ºÜÊ (stress-only ¾«Fick Ê (stress-strain unaffected» ¾ Ä ¾ À»À Ê л Ï» ÅÓ¼ Fick Ê» À ² ² ÁÚ¾ ÅÔ» ÎÁÚ Ê» Ó Ä ÅԻʠº ÏÚÅ 8 ¼² Í» Ò¾É Ä Þ À h 50 h 100 h 200 h 600 h 1000 h 2000 h Fig.6 Plot of normalized hydrogen concentration C/C eq vs normalized distance r/r 0 from the center of the cold drawn steel wire as result of stress-strain assisted diffusion (a unaffected (b unaffected Fig.7 Hydrogen concentration distributions in cold drawn steel wire at indicated diffusion time (a10 h, (b600 h as results of stress-strain assisted diffusion, stress-only assisted diffusion, and stressstrain unaffected diffusion

5 206 Ͻ ³ Ý (a unaffected t /h 0.8 (b unaffected t /h Fig.8 Hydrogen concentration distributions in cold drawn steel wire at indicated depths (a r/r 0 =; (b r/r 0 =0.9 as results of stress-strain assisted diffusion, stress-only assisted diffusion, and stressstrain unaffected diffusion ²» ¼¹» Ö Ä º» Ð È Ï ÇÑ ÅԻʠ± ± ÅÔ Ó Ñ Ñ» Ë ÊÂÁ à (7 Õ» Ê РÀ È» Ð ± ¼ÅÔ Ä»À ³ (8 Ö Æ ³ Ä È Ï ß ²» Ð Ó¼ÎÁÚ¾ ºÜ» л 8 ÔÄ»ÊÂÒÞ Å Æ 6 Æ (1 Ì ABAQUS Æ Ì Æ¾ Ì ÆÌÙ Þ Æ¾ ¾ÍÜ ¼ Æ Ì Ð Þ Æ À ÀÏ Ó ¾Í Ó ÅÔ Ð ±ÆÀ ÔÓ Ã À» Ñ ÀÏ À Æ Ì Đ ²»À Ð ³Ò À Æ Ì Ñ (2 ÀÛ ÁÚ¾»ÊÂ Ì Æ ºÜ»ÊÂ Ì ÌÙ Þ Æ Ã» ¾Í Ü ¼¾ À º» Ê РÅÔ»ÊÂÔ Ó À Æ» ÑĐÙ» Ð ¼ Õ À Ó» ÁÚ¾ÅÔ»ÊÂ Ï É (3 À ¼ÅÔ»À ÊÂÁ ² ÁÚ¾ ²» ÐĐ ¼ÎÁÚ ºÜ ²» ÐĐ Ö Ä ²» Ð ÅÓ¼ÎÁÚ ºÜ» Ð Ô [1] Schupack M, Suarez M G. Some recent corrosion embrittlement failures of prestressing system in the United States [J]. J. Prestress. Concr. Inst., 1982, 27(2: [2] Toribio J, Lancha A M. Effect of cold drawing on susceptibility to hydrogen embrittlement of prestressing steel [J]. Mater. Struct., 1993, 26: [3] American Concrete Institute, ACI R-01, Corrosion of Prestressing Steels [M]. Detroit MI, [4] Klodt D T. Studies of electrochemical corrosion and brittle fracture susceptibility of prestressing steel in relation to prestressed concrete bridges [A]. Proceedings of 25th Conference of National Association of Corrosion Engineers [C]. Houston, Texas, 1969: [5] Toribio J. Role of hydrostatic stress in hydrogen diffusion in pearlitic steel [J]. J. Mater. Sci., 1993, 28(9: [6] Lin B. Study of effect of stresses on the fracture behavior and corrosion of prestressing steel wires [D]. Shanghai: Shanghai Jiaotong Univ., 2007: (Õ. ÒÖ ² Đ [D]. È : È ±Õ. 2007: [7] Elices M, Ruiz J, Atienza J M. Influence of residual stresses on hydrogen embrittlement of cold drawn wires [J]. Mater. Struct., 2004, 37: [8] Toribio J, Elices M. Influence of residual stresses on hydrogen embrittlement susceptibility of prestressing steels [J]. Int. J. Solids. Struct., 1991, 28(6: [9] Kharin V, Toribio J. Effect of residual stress profile on hydrogen embrittlement susceptibility of prestressing steel [J]. Anales De Mecánica De La Fractura, 2005, 22: [10] Elices M. Influence of residual stresses in the performance of cold-drawn pearlitic wires [J]. J. Mater Sci., 2004, 39(12: [11] Brass A M, Chene J. Influence of deformation on the hydrogen behavior in iron and nickel base alloys: a review of experimental data [J]. Mater. Sci. Eng. 1998, A242: [12] Nagumo M, Takai K, Okuda N. Nature of hydrogen trapping sites in steels induced by plastic deformation [J]. J. Alloy Compd, 1999, :

6 3 ¼ : ¼Ëà Íб 207 [13] Zhang X H, Chen P Y, Tan C Y. Effect of stress and plastic strain on hydrogen diffusion in welded joint of implant test [J]. Trans. China Weld. Inst., 2002, 23(2: 9-12 (ÆÇÖ, É, ÇĐ. / ±Ä µ½ ÌÄ ² [J]., 2002, 23(2: 9-12 [14] Toribio J, Kharin V. A hydrogen diffusion model for applications in fusion nuclear technology [J]. Fusion Eng. Des., 2000, 51-52: [15] Hirth J P. Effects of hydrogen on the properties of iron and steel [J]. Metall. Trans., 1980, 11A: [16] Van Acker K, Root J, Van Houtte P, et al. Neutron diffraction measurement of the residual stress in the cementite and ferrite phases of cold-drawn steel wires [J]. Acta Mater., 1996, 44(10: [17] Atienza J M, Martinez-Perez M L, Ruiz-Hervias J. Residual stresses in cold drawn ferritic rods [J]. Scr. Mater., 2005, 52: [18] Atienza J M, Ruiz-Hervias J. Residual stresses in cold drawn pearlitic rods [J]. Scr. Mater., 2005, 52: [19] Toribio J, Toledano M. A fracture criterion for prestressing steel cracked wires [A]. Advances in Steel Structures(ICASS 99 [C]. Pergamon, 1999: [20] Kharin V, Blanco J A, et al. Influence of cold drawing on residual stresses and hydrogen embrittlement of prestressing steels [A]. 10 th Portuguese Conference on Fracture [C]. 2006: 1-9 [21] Morton K W, Mayers D F. Numerical Solution of Partial Differential Equations [M]. UK: Cambridge University Press, 2005, [22] Zou T. Hydrogen brittleness phenomena brought by steel wire pickling and its settling measure [J]. Steel Wire Prod., 2007, 33(4: (Ý. À ½ É ± Ð [J]. Ü, 2007, 33(4: INFLUENCE OF RESIDUAL STRESS AND STRAIN GENERATED BY COLD DRAWING ON HYDROGEN DIFFUSION PROFILES OF STEEL WIRES WANG Yanfei, GONG Jianming, TANG Jianqun, JIANG Wang, JIANG Yingjie College of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing Abstract: High strength steel wires are susceptible to hydrogen induced fracture. It is generally considered that fracture will occur when a critical hydrogen concentration at the location of the stress peak was reached by accumulation, and that the time to fracture was related to the stress assisted hydrogen diffusion process. Residual stresses generated by cold drawing play an important role in hydrogen accumulation. However, plastic strain also has significant effect on the hydrogen diffusion process. In this paper, a numerical model was developed for calculating the accumulated hydrogen concentration in cold drawn steel wires, taking into account the driving effect of both the residual stress and strain generated by cold drawing on hydrogen transport. First, a finite element model, using the code ABAQUS, was developed to reproduce the drawing process, and to determine the residual stress and strain profiles. The results showed that the drawing process generated a residual stress state in the wire with significant tensile stresses at the surface in the axial and hoop directions. Finite difference method was used to solve the stress-strain assisted and stress-only assisted hydrogen diffusion equations. The hydrogen concentration accumulated in stress-strain assisted case is lower than that in stressonly assisted case in shorter time, that was slowed down by plastic strain due to diffusion. However, after long exposure time, the hydrogen concentration was much higher than that in stress-only affected case. The results in this paper prove the relevant role of residual plastic strain in hydrogen diffusion in cold drawn wires, as well as the residual stress. Key words: cold drawing, residual stress, strain, hydrogen diffusion, steel wires