Study on Welding Inherent Deformations in Welded Structural Materials

Transcription

1 Transactions o JWRI, Vol. 37 (8), No. 1 Study on lding Inerent Deormations in lded Structural Materials WANG Rui *, RASHED Seri **, SERIZAWA Hisasi***, MURAKAWA Hidekazu**** and Jianxun ZHANG ***** Abstract It is meaningul to predict welding deormation in practical time and to apply tese data in welding industry. In tis paper, te inerent deormations o beading on plate welding and illet welding are studied. A 3D termal-elastic-plastic FEM based on interactive substructure metod (ISM) is used to predict te welding deormations. Experiments are carried out to veriy te computation results. Based on te computation results, te inverse analysis metod is proposed to estimate te inerent deormations. Using inerent deormations, welding deormation can be accurately reproduced by elastic FEM wic is muc more practical and eicient. Finally, a database o inerent deormations on bead on plate welding and illet welding including 8 dierent materials is developed. Meanwile, te relationsip o welding eat input and inerent deormations is discussed. Te eectiveness o tis metod is also conirmed by experimental results. KEY WORDS: (FEM) (lding distortion) (Inerent deormation) (Inverse analysis) (Inerent deormation database) 1. Introduction lding is widely used in sipbuilding, aerospace and automotive industries or assembling various products. However, welding distortion is one o inevitable problems during welding. lding distortion as an adverse eect on abrication precision, structures unction, productivity and increase abrication costs. Tereore, an analysis metod to estimate welding distortion avoiding welding distortion problems at industrial production is essential. Finite element tecniques ave been used in te prediction o welding residual stress and distortion or more tan tree decades 1~6). Some useul simpliied ormulae and eecting actors or predicting welding distortion ave been presented. However, most o tem just discuss te speciied welding problem. So it is important to create te database about welding distortion or typical welding joints tat is useul or predicting te welding distortion in practical welding industry. Generally, te welding deormations are classiied into our undamental types, transverse srinkage, longitudinal srinkage, transverse bending, and longitudinal bending. Tese our types o deormations can be regarded as undamental components o te inerent deormations due to welding. Assuming te inerent strain is te initial strain, welding deormation can be easily predicted by elastic inite element analysis, Received on July 11, 8 * Foreign Visiting Researcer, Xi an Jiaotong University ** Specially Appointed Proessor *** Associate proessor omitting te complicated termal elastic-plastic inite element analysis. Te inerent strain metod is more 7, 8) practical and eicient. Ueda et al. studied te caracteristic distributions o inerent strains in typical weld joints and employed inerent strains to predict te welding residual stress. Murakawa et al. 9~11) used a simpliied analysis model to obtain inerent strain. Tey represented te inerent strain as a unction o te igest temperature and degree o restraint. Based on te inerent strain metod, welding deormation and residual stress were investigated. Jang et al. 1, 13) estimated te inerent strain region and investigated te inerent strain as a unction o te mecanical melting temperature and te degree o restraint, at te same time welding deormations in large structures were predicted. Liang et al. 14, 15) using an inverse analysis metod studied te caracteristic distributions o inerent strains in bead on plate welding and used tem to predict te welding deormations. Deng et al. 16) using te inerent strain metod combined wit termal elastic-plastic inite element analysis predicted te welding distortion in large structures. In tis study, a database o inerent deormations according to 8 dierent materials and 144 computation cased is created and te welding parametric eects on inerent deormations are also discussed. First tree-dimension termal-elastic-plastic inite element *** * Proessor ***** Proessor, Xi an Jiaotong University Transactions o JWRI is publised by Joining and lding Researc Institute, Osaka University, Ibaraki, Osaka , Japan 91

2 Study on lding Inerent Deormations in lded Structural Materials simulation o interactive substructure metod (ISM) is used to predict te welding deormations o typical welding joints, bead on plate welding joints and illet welding joints. Meanwile, based on te inverse analysis metod, te inerent deormations are estimated by termal-elastic-plastic FEM computation results. Furter, using inerent deormations, te elastic FEM is employed as te orward analysis to reproduce te welding distortions. By comparing wit te experiment results, te eectiveness o te simulation result is conirmed.. Experiment procedure Experiments are conducted to veriy te eectiveness o te numerical results. Two typical welding joints, namely bead on plate welding joint and illet welding joint are abricated and teir welding temperature and deormations are measured. Te welding metod used in te experiment is CO gas metal arc welding. Te base metals are carbon steel and stainless steel. Te iller materials are MGS-5 and GFW38L, respectively. For bead on plate welding, experimental set up is sown in Fig.1. Te plate sizes are mm mm. For illet welding, te size o lange is mm mm and tat o web is mm 5mm, and te experimental set up is sown in Fig.. Te plate tickness and welding conditions or bead on plate welding and illet welding are given in Table 1. Fig.1. Experiment set up o bead on plate welding Fig.. Experiment set up o illet welding Table 1 lding condition. Case No. Joint Material Plate tickness (mm) Current (A) Voltage (V) Speed (cm/min) Wire eed rate (mm/s) 1 Bead on plate welding Bead on plate welding Fillet welding (pass 1) (pass ) Fillet welding (pass 1) (pass ) Prediction o welding deormation In general, two metods can be used to obtain te inerent deormations. One is te experimental metod and te oter is numerical simulation using termal elastic plastic FEM. In tis section, two metods o termal elastic plastic FEM and elastic FEM are used to estimate te welding distortion, respectively. First, welding deormations are analyzed by tree-dimension (3D) termal elastic plastic FEM using interactive substructure metod (ISM) 17). Meanwile, te distribution o inerent deormations or bead on plate welding and illet welding can be computed by inverse analysis metod 14). Ten, using inerent deormations as initial deormation, elastic sell FEM can be used to reproduce te welding deormation D termal elastic plastic inite element model In tis investigation, te 3D uncoupled termal-mecanical analysis is adopted. First, termal analysis is computed. Ten, te temperature istory is employed as a termal load in te subsequent mecanical analysis. Temperature dependent material properties are incorporated in te termal and mecanical analysis. Fig.3 sows te inite element mes models o bead on plate welding and illet welding wicere used in te simulation. For te bead on plate model, te lengt o te plate is uniormly divided into 5 and 4 elements in te welding and tickness direction. It results in 946 nodes and 6968 elements. It as a iner mes grid in te welding zone. For illet welding model, te mes metod is te same as or bead on plate welding. Te FEM model as 1839 nodes and 144 elements. Te dimensions o te inite element model and te boundary conditions (sown in Fig.3 by arrows on specimens) are te same as tose o used in te experimental specimens. 9

3 Transactions o JWRI, Vol. 37 (8), No. 1 Z X Y (c) Z X Y (d) Fig.3. Finite element model: bead on plate welding o case 1, and illet welding o case Computation results o ISM lding temperature and distortions including, transverse srinkage, angular distortion, and longitudinal srinkage are predicted or bead on plate welding and illet welding. Fig.4 sows te comparison o usion boundaries between experiment results and computation results rom case1 to case 4. Te predictions capture te overall dimensions o te usion boundaries. From tese igures it can be concluded tat te overall macrosection sapes o computational and experimental results are identical. Te comparison results validate te eectiveness o termal analysis. Fig.4. Temperature results: case 1, case, (c) case 3, and (d) case 4 Fig.5~ Fig.7 sow te comparison results o welding distortion between experiment and computation. Troug te comparison o computation wit experimental results, it can be observed tat te computation results are in excellent agreement wit experiment results. Te welding distortions can be accurately predicted by ISM. Te distortion results sow tat tere are not large dierences o welding deormations along te welding direction. Tereore, te deormations can be assumed to distribute uniormly along te weld line. Transverse srinkage (mm) Experimental result o case 1 Computational result o case 1 Experimental result o case Computational result o case X-Coordinate (mm) 93

4 Study on lding Inerent Deormations in lded Structural Materials Transverse srinkage (mm) Experimental result o case 3 Computational result o case 3 Experimental result o case 4 Computational result o case X-Coordinate (mm) Longitudinal srinkage( 1 3 ) (mm) Y-Coordinate (mm) Experimental result o case 3 Computational result o case 3 Experimental result o case 4 Computational result o case 4 Fig.5. Transverse srinkage: bead on plate welding, and illet welding Angular deormation (deg) Angular deormation (deg) Fig Longitudinal srinkage( 1 3 ) (mm) Experimental result o case 1 Computational result o case 1 Experimental result o case Computational result o case X-Coordinate (mm) Experimental result o case 3 Computational result o case 3 Experimental result o case 4 Computational result o case X-Coordinate (mm) Angular distortion: bead on plate welding, and illet welding Y-Coordinate (mm) Experimental result o case 1 Computational result o case 1 Experimental result o case Computational result o case Fig.7. Longitudinal srinkage: bead on plate welding, illet welding 3. Elastic FEM analysis o welding deormation Te welding deormation is assumed to be caused by our components o inerent deormation, namely longitudinal srinkage (δ i x ), transverse srinkage (δ i y ), longitudinal bending (θ i x ), and transverse bending (θ i y ). Tese our components are deined by te ollowing equations: i i δ x = ε xdydz / (1) i i δ y = ε ydydz/ () θ i i 3 x = ε x ( z / ) /( /1) dydz (3) θ i i 3 y = ε y ( z / ) /( /1) dydz (4) Were x is welding direction, y is te direction vertical to welding direction, is te tickness o plate, ε i x is te inerent strain in te X direction, and ε i y is te inerent strain in te Y direction. use te inerent deormation metod, in wic te inerent deormations are introduced into te elastic FE analysis, to predict te welding distortion. On te contrary, i te welding deormations are given rom experimental measurements or termal elastic plastic FE analysis, te inerent deormation can be calculated by te metod o inverse analysis 14). In tis section, two computation cases, case and case 3 (as sown in table1) are taken as examples to describe te prediction results o welding distortion using inerent deormation metod. Fig.8 and sow te sell models o case and case 3, respectively. Te areas were te inerent deormations are introduced are sown in large mes size. Te mes o te sell model is te same as 3-D termal elastic plastic inite element model. 94

5 Transactions o JWRI, Vol. 37 (8), No. 1 Zone o inerent strain Fig.9 Prediction o welding deormation by elastic FEM: bead on plate welding o case, and illet welding o case 3 Zone o inerent strain Fig.8. Te sell model or elastic analysis: bead on plate welding o case, and illet welding o case Computation results o elastic FEM As one o te computation results, te angular deormation distributions are sown in Fig.9. Meanwile, te computational results o angular deormation distributions by termal elastic plastic FE analysis are sown in Fig.1. Te comparison o deormations accuracy o experiment and tose calculated rom te elastic FE analysis are compared in Fig.11. As seen rom Figs 9-11, te prediction results o welding deormation by inerent deormation metod coincide airly well wit tose by termal elastic plastic FE analysis. Tese results indicate tat inerent deormations metod is eective or predicting welding distortion. Using tis metod, an elastic sell model is used to accurately predict te welding deormations. Te computational time by elastic FEM is muc sorter tan termal-elastic-plastic FEM. Fig.1. Prediction o welding deormation by elastic-plastic FEM: bead on plate welding o case, and illet welding o case 3 Deormation (mm) Experiment Inverse analysis Number o deormation components 95

6 Study on lding Inerent Deormations in lded Structural Materials Deormation (mm) Experiment Inverse analysis Number o deormation components Fig.11. Te comparison o deormation measurement and orward analysis: bead on plate welding o case, and illet welding o case 3 4 Te database o inerent deormation on dierent materials Te inerent deormations are mainly determined by te welding eat input, te tickness o members and te type o welding joint 18~). Base on te above analysis, te inerent deormations can be accurately estimated by inverse analysis. Once te relation between inerent deormation and welding parameter is created, te welding deormation o welded structure can be predicted by elastic FEM. Tus, te idea o building up a database o inerent deormation is important in predicting welding distortions, especially or large welding structures. Using te results o inerent deormation database, it can easily demonstrate ow muc deormation will be produced in a given welding eat input condition. 4.1 Computation cases Te database o inerent deormation as been built up or 8 dierent materials. Te range o parameters used in te computation is according to table. Table Range o parameters or computation cases lding joint Bead on plate joint Plate tickness (mm) 3, 3., 3.6, 4, 4.5, 5 lding current (A) lding voltage (V) lding speed (mm/s) Fillet joint 4.5, 5, 6, Material,,,,,,, 4. Computation results o bead on plate welding Te inerent deormations are closely related wit welding eat input (Q), te tickness o members () and te type o welding joint. In case o bead on plate welding, all o te welding eat input is given to te welding plate as sown in Fig.1. Te relationsip o inerent deormations wit bead on plate welding can be deined as te relationsip o inerent deormations wit parameter Q total/. Q Total wit Q total/or bead on plate welding are sown in Fig.13. Te researc results in paper 18) and in tis study are sown in Fig.13 and, respectively. For Fig.13, te dierent symbols designate dierent materials and te plots indicate te trend lines. It can be seen rom te results tat transverse srinkage (TS/) linearly increases wit Q total/. Because o dierent material properties, te magnitude and tendency o transverse srinkages sow some dierences or dierent materials. Te researc results in tis study sow a good agreement wit experiment results in paper 18). Fig.1. Heat input distribution in bead on plate welding joint 4..1 Transverse srinkage Te relation o transverse srinkage witelding eat input in bead on plate welding as been studied by 18, 19). Te transverse srinkage (TS) can be expressed in te ollowing equation: Q TS / = (5) Were, Q is welding eat input, is plate tickness. Te variation caracteristics o transverse srinkage 96

7 Transactions o JWRI, Vol. 37 (8), No. 1 TS/ Fig.13. Te relation o transverse srinkage witelding eat input or bead on plate welding: experiment result o transverse srinkage 18), and computation result o transverse srinkage 4.. Transverse bending Transverse bending (TB) on bead on plate welding can be teoretically predicted by te ollowing equation 18) : * 61Q TB = * ( Q 6.16) (6) Were, Q* is Q/, Q is welding eat input, is plate tickness. Te variation caracteristics o transverse bending wit Q total/or bead on plate welding are sown in Fig.14. Te researc results in paper 18) and in tis study are sown in Fig.14 and, respectively. From Fig.14, it can be seen tat transverse bending (TB) appears a contrary caracteristic compared wit transverse srinkage wen Q total/ is during 1~3 (J/mm 3 ). Te transverse bending decreases wit Q total/ increasing. Te maximum transverse bending (TB) obtained wen Q total/ kept at almost 1 (J/mm 3 ). Comparing wit Fig.14, wen welding eat input is smaller tan 1 (J/mm 3 ), te transverse bending is increasing wit Q total/. Te transverse bending is decreasing wit Q total/en Q total/ is larger tan 1 (J/mm 3 ). Te expected researc results in tis study coincide wit experiment results in paper 18) Q total / (J/mm 3 ) TB (radian) Q total / (J/mm 3 ) Fig.14. Te relation o transverse bending witelding eat input or bead on plate welding: experiment result o transverse bending 18), and computation result o transverse bending 4..3 Longitudinal srinkage For longitudinal srinkage, irst Tendon Force (F) is calculated by te ollowing ormula (Res, 1, ): F =. Q (7) Were, Q is welding eat input. Ten te Tendon Force (F) is converted to equivalent longitudinal srinkage (LS) expressed by te ollowing equation: F = ELS (8) Were, E is Young s Modulus, is plate tickness. For a given welding eat input, according to equations (7) and (8), te approximate expression or LS can be described as: Q LS / = ( ) E (9) Fig.15 sows te researc results o longitudinal srinkage in tis study. As seen rom te igure, te longitudinal srinkage (LS/) linearly increases wit Q total/. Te researc results coincide wit te teoretical prediction equation. Te magnitude o longitudinal srinkage is muc smaller tan transverse srinkage wen Q total/ canges rom 1 (J/mm 3 ) to 4 (J/mm 3 ). LS/ Q total / (J/mm 3 ) Fig.15. Te relation o longitudinal srinkage witelding eat input in bead on plate welding 4..4 Longitudinal bending 97

8 Study on lding Inerent Deormations in lded Structural Materials Fig.16 sows te researc results o longitudinal bending. From te igure, it is seen tat te longitudinal bending (LB) decreases a little wit Q total/ increasing. Because o dierent material properties, te canging extent o longitudinal bending sows a little dierence. However, te magnitude o longitudinal bending is muc smaller tan transverse bending or all cases Transverse srinkage Te relation o transverse srinkage (TS) wit Q/ on lange and web o illet welding is sown in Fig.18 and. It is seen rom te results tat transverse srinkage (TS) bot on lange and web linearly increase wit Q/. Comparing between Fig.18 and Fig.18, te transverse srinkage (TS) o te lange is larger tan tat o te web. LB (radian) TS/ -1 Q total / (J/mm 3 ) Fig.16. Te relation o longitudinal bending witelding eat input in bead on plate welding 4.3 Computation results o illet welding In te case o illet welding, as sown in Fig.17, te welding eat input is given to bot te lange and web. Te distribution o eat input in te lange and te web are deined by te ollowing equations 15) : w w Q web = Qtotal = ( QL + Q + + w w R ) (1) Q lange = Qtotal = ( QL + QR ) + w + w (11) Were, Q total is total eat input, QL and QR are eat input in let side and rigt side, respectively, and are te tickness o web and lange, respectively. b Fig.17. Heat input distribution in illet welding joint TS/ Q lange / (J/mm 3 ) Q web / (J/mm 3 ) Fig.18. Te relation o transverse srinkage witelding eat input in illet welding: transverse srinkage on lange, and transverse srinkage on web 4.3. Transverse bending Fig.19 and sow te relationsip o transverse bending (TB) o lange and web wit Q/ on illet welding. From Fig.19, it is seen tat transverse bending linearly increases wit Q/ increasing wen Q/ is larger tan 1 (J/mm 3 ). Comparing between Fig.19 and Fig.19 sows tat transverse bending in te web canges slowly wit Q/ increasing. Te magnitudes o transverse bending in te web almost keep constant wit Q/ increasing. It can be concluded tat Q/ as less inluence on transverse bending in te web o illet welding. According to equation (1) and (11), te eat input or te lange and te web o illet welding are dierent. So te illet welding joint will be divided into te lange and te web or discussion, respectively. Te relationsip o welding inerent deormation witillet welding can also be deined as te relationsip o welding inerent deormation wit Q/. 98

9 Transactions o JWRI, Vol. 37 (8), No. 1 TB(radian) TB(radian) Fig.19. Te relation o transverse bending witelding eat input in illet welding: transverse bending on lange, and transverse bending on web Longitudinal srinkage Te teoretical calculation o longitudinal srinkage or illet welding is te same as or bead on plate welding. Te longitudinal srinkage can be calculated rom te Tendon Force 1). In tis study, te relation o longitudinal srinkage (LS) wit Q/ in illet welding is sown in Fig.. From Fig. and, it is seen tat longitudinal srinkage linearly increases wit Q/. Comparing between Fig. and, it can be seen tat te magnitudes o longitudinal srinkage in te lange are a little larger tan tose in te web. LS/ Q lange / (J/mm 3 ) Q web / w (J/mm 3 ) Q lange / (J/mm 3 ) LS/ Q web / w (J/mm 3 ) Fig.. Te relation o longitudinal srinkage witelding eat input in illet welding: longitudinal srinkage on lange, and longitudinal srinkage on web Longitudinal bending Te relation o longitudinal bending (LB) o lange and web wit Q/ in illet welding is sown in Fig.1 and. From Fig.1, it is seen tat longitudinal bending linearly increases wit Q/ wen Q/ is larger tan 1 (J/mm 3 ). Comparing te computation results between Fig.1 and Fig.1 sow tat longitudinal bending in te web canges slowly wit te Q/ increasing. LB (radian) LB (radian) Q lange / (J/mm 3 ) b QR Q web / (J/mm 3 ) Fig.1. Te relation o longitudinal bending witelding eat input in illet welding: longitudinal bending on lange, and longitudinal bending on web 6 Conclusions According to te researc results in te present work, te conclusions are summarized as ollowing: (1) Using ISM, te welding deormation can be numerically predicted in typical welding joints. Te 99

10 Study on lding Inerent Deormations in lded Structural Materials prediction results are in good agreement wit experiment results. () Inerent deormations can be estimated by inverse analysis. Furtermore, welding deormation can be estimated by elastic FEM based on inerent deormations results. Te complicated termal elastic plastic problem is translated into a simple elastic problem. Te elastic FEM can save muc computation time. Te comparison between computation and experiment results concludes tat te elastic FEM result is validated. (3) Te approac and model used in tis study are sown to be eective and eicient to estimate te inerent deormations o typical welding joints. A database o inerent deormations based on 8 dierent materials is developed based on te computation results in tis study. (4) Te eect o Q/ or inerent deormations on bead on plate welding is investigated. Te analysis results sow tat or bead on plate welding, te transverse srinkage is linearly increasing wit Q/. Te transverse bending is decreasing wit Q/ wen Q/ canges rom 1 to 4 (J/mm 3 ). Te maximum transverse bending obtained wen te Q/ is kept at 1 (J/mm 3 ). Te longitudinal srinkage is linearly increasing wit Q/. Te magnitude o longitudinal srinkage is muc smaller tan transverse srinkage. Te longitudinal bending decreases a little wit Q/ increasing. Te magnitude o longitudinal bending is smaller tan transverse bending. (5) Te eect o Q/ on inerent deormations o illet welding is also investigated in tis study. Te researc results indicate tat wen eat input canges rom 1 to 4 (J/mm 3 ), te inerent deormations linearly increase wit te increasing o Q/ on illet welding. Comparing te computation results o inerent deormations between te lange and te web o illet welding, te results sow tat te magnitudes o inerent deormations on te web cange little wit Q/ increasing. Te Q/ as less eect on te inerent deormations in te web o illet welding wen Q/ canges rom 1 to 4 (J/mm 3 ). Acknowledgements Tis researcas te results o Survey and researc on building welding inerent deormation database and data generation, wicas supported by te New Energy and Industrial Tecnology Development Organization (NEDO). Reerences 1) V. J. Papazoglou and K.Masubuci. ld. J. 57(9): 51 6, ) W. Woo, H. Coo, D. W. Brown, Z. Feng, P. K. Liaw. Mater. Sci. Eng. A. 437: 64-69, 6. 3) C.L.Tsai, S.C.Park, W.T.Ceng. ld. J. 78(5): , ) A.K.Dingra, C.L.Murpy. Sci. Tecnol. ld. Join. 1(5): , 5. 5) M. A. Zaeem, M.R.Nami, M.H.Kadivar. Sci. Forum : , 6. 6) P.Dong. Sci. Tecnol. ld. Join. 1(4): , 5. 7) Y. Ueda, M.G.Yuan. J. Engrg. Mater. Tecnol. 115 (1): , ) M.G.Yuan, Y.Ueda. J. Engrg. Mater. Tecnol. 118 (4):9-34, ) H. Murakawa, Y.Luo, Y. Ueda. J. Soc. Naval Arcitect. Jpn. 18: , ) Y.Luo, H. Murakawa, Y. Ueda. J. Soc. Naval Arcitect. Jpn. 18: , ) Y.Luo, H. Murakawa, Y. Ueda. J. Soc. Naval Arcitect. Jpn., 183: , ) C.D.Jang, C.H.Lee, D.E.Ko. Proc. Instn. Mec. Engrs. 16: ,. 13) S.I.Seo, C.D.Jang. J.Sip Prod. 15(): 73-81, ) W. Liang, S.J. Sone, M. Tejima, H. Serizawa, H.Murakawa. Transactions o JWRI. 33(1): 45-51, 4. 15) W.Liang, D.A. Deng, H.Murakawa. Transactions o JWRI. 34(1): , 5. 16) D. A. Deng, H. Murakawa, W. Liang. Comput. Metods Appl. Mec. Engrg. 196: , 7. 17) H.Nisikawa, H.Serizawa, H.Murakawa. Sci. Tecnol. ld. Join. 1(): , 7. 18) K. Sato, T. Terasaki. Quar. J. JWS. 45(4): 3-38, ) Y.Takeda. J. Sip Prod. 18(): 99-14,. ) T.Terasaki, T.Isimura, K.Matsuisi, T.Akiyama. Quar. J. JWS. (1): ,. 1) T.Terasaki, T.Kitamura, I. Kidota, T.Isimura, S.Hamasima. Quar. J. JWS. 1(1): 81-86, 3. ) C.L.M.Cottrell. ld. J. 3: 57-7,