Numerical Study on Welding Line Behavior of Deep Drawing TWB Process

Available online at www.sciencedirect.comScienceDirectJOURNAL OF IRON AND STEEL RESEARCH ,INTERNATIONAL 2007 ,14(5 ):36-38 ,46Numerical Study on Welding Line Behavior of Deep Drawing TWB ProcessWANG Li-juan，WANG Guo-dong，LIU Xiang-hua ，WU Ming-tang( State Key Laboratory of Rolling Automation and Technology , Northeastern University , Shenyang 110004 , Liaoning , China )Abstract :The FEM technology is used to analyze the welding line movement behavior of deep drawing TW B sheet with dif-ferent thickness. It is found that high stress fields are concentrated around the welding line and large residual stresses areleft. The effect of the welding line movement is like a rigid string and the selected nodes of the thin part near the weldingline show the related larger strain.Key words : welding line ; behavior ; deep drawing ;TWBTailor-welded blanks( TWB ) are composed of twoor more sheets of metal with dissimilar strength and/ orthickness that are welded into a single blank. TWBs arestamped into automotive body panels and offer reducedpart weight and improved material use'T. They are mostcommonly fabricated using a laser welding process ,which creates a narrow weld and a heat -affected zone( HAZ ) at the junction of dissimilar sheets.As the variety of TWB applications increases , theefects of the weld on blank formability may become moresignificant and hence it is important to understand theseFig.1 Deep drawing die modeleffects. The objective of this research is to perform a nu-merical study on the welding line behavior of the deepdrawing TWB process1 Simulation ConditionsUsing ANSYS_ DYNA explicit analysis , drawing theTWB sheet process is simulated with a thickness ratio of1: 1.2. The drawing dies are shown in Fig. 1 and theirelement type is SOLID164 with rigid behavior. The TWBsheet is a planar blank sheet with different thickness and itselement type is SHELL163. The density of the sheet is 78000 kg/m3 ,its Ex is2. 06x10 MPa ,Nuxy is 0.3 ,andthe yield stress is 235 MPa. The Ex of the welding lineis2.1 x10' MPa , Nuxy is 0.3 , and the yield stress is中国煤化工.500 MPa. The drawing speed is 0. 055 8 m/s. The sim-CHCNMHGulation models use 4 391 nodes and 11 378 elements Fig. 2 Node model of 1W B sheet( with seleted node labels )( shown in Fig.2 ).Biography :W ANG Li-juan( 1970-) , Female , Doctor , Engineer ; E-mail : wangj@ mail neu. edu. en; Revised Date : September 20 ,2006No. 5Numerical Study on Welding Line Behavior of Deep Drawing TWB Process. 37obviously high stress field and large deformation. Later ,2 Analysisduring the drawing process , the high stress fields con-2.1 Dynamic stress distribution of TWB sheetcentrate on the side part of the TWB sheet near the weld-The planar V onmises stress distribution ( zoomeding line at 0. 2 s and develop throughout the whole weld-with a0. 001 scale ) of the TWB sheet at different timesing line at 0.5 s , while the circular iso-stress lines atis shown in Fig3. A welding line is located in the mid-0.3 s are changed into the discontinuous stress fields. Atdle sheet , which is the stress concentration center4i. Inthe end of the drawing process , the large residual stress .the beginning of the TWB drawing , the thin part showsTime=0.1sTime=0.2 sCeTime=0.3sTime=0.5sTime=0.8 sTime=1.0s中国煤化工MYHCNMHGFig. 3 Vonmises stress distribution of TWB sheet at different times ( a welding line in middle sheet )Jourmal of Iron and Steel Research , InternationalVol. 14is left in the welding line at 10 s. .that makes the thin part of the lateral TW B sheet has lar-ger displacement than the thick part. The lateral sheet2.2 Welding line behaviorhas crimples , and the distortion phenomenon is shown inThe Uz welding line displacement is shown irFig. 5.Fig. 4 ; the center welding line movement is very small inIt is seen from Fig. 5 that the residual strain isthe Uz direction even when large stresses are concentrat-concentrated around the side of the drawing cup anded on[S6] , the lateral welding line has large displace- high residual Vonmises stress field is on the weldingment in the opposite direction and the maximum value isline. The crimples have larger residual strains and22.1 mm. The whole welding line just likes a rigidlower residual stresses than the normal parts. Sincestring which is changed into the opposite”U" type ，the circular side of the drawing cup has not uniform0.10 |plastic strains and then deformation extends to the0.10-0.56. Side 1Thin blank node--- Side 2 Thick blank node-0.50 I0.08昏--0.81 t-1.00 t0.06-1.20 t' -1.530.049 -1.78-1.970.02-2.2100.48 0.961.441.92 2.40Welding line length/dm0.3Fig. 4 Uz welding line displacementSide 3 Thin blank node-. Side 4 Thick blank node0.24(aA=0.112B=0.335C=0.5580.16D 1001F-1.226G=1.449H=1.6721=1.8950.01(. Side 5 Thin blank node0.008--- Side 6 Thicl blank node三0.0060.004 |(bUnit: MPaA=40.80.002E2254F-3070.064一Side 7 Thin blank nodeG=360.H=4140.048--- Side 8 Thick blank node如哥1=4670.032中国煤化工MHCNMHG.0.0.60.81.0Time/sFig.6 Vonmises strain curves at selected nodes near( a)Strain ; ( b ) Vonmises stresswelding line( Continued on Page 46 )Fig. 5 Strain and stress distributionJourmal of Iron and Steel Research , InternationalVol. 14London :The Metal Society , 1978.[ 15 ] Grigoryan V , Belyanchikov L , Stomakhin A. Theoretical[8]SvobodaJ M ,Monroe R W ,Bates C E ,et al. 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[14 ] Linchevsky B , Sobolevsky A , Kalmenev A. lron and Steel-[22] ASM Handbook Vol.3 " Alloy Phase Diagrams"[ M] 10 th Ed.making[ M ] Moscow : Mir Publishers , 1980.1992.( Continued From Page 38 )outside of the TWBwhich is changed into the opposite" U" type ;sheet and sets free to make the related outside part enter( 4 ) The crimples have larger residual strains andcrimples.lower residual stresses than the normal parts.Vonmises strain curves at selected nodes near thewelding line are shown in Fig 6. Except nodes 3 and4，References :the other nodes have a larger strain on the thin part and asmaller level of Vonmises strain than nodes3 and 4. On1 ] Tusek J , Kampus Z , Suban M. Welding of Tailored Blanks ofDifferent Materials[ J ] Joumal of Material Processing Technology,the side of the drawing cup( located by nodes 3 and 4 )2001 , 119 :180-184.with large plastic deformation , the thick part has a larger [ 2] Kampus z , Balie J. Deeping Drawing of Tailored Blanks With-strain than the thin part. All related locations of theout a Blank Holder[ J ]. Journal of Material Processing Technology ,2003 , 133 :128-133.welding line have strains of 0.01 which are like" a rigid[3] Scott D Raymond , Peter M Wild , Chrstopher J Bayley. Onstring".Modeling of the Weld Line in Finite Element Analysises of Tai-lor-Welded Blank Forming Operations [ J ] Jourmal of Materials3 ConclusionsProcessing Technology ,2004 ,147 :28-37.The following results were obtained :4] ZHANG Shi-hong , CHENG Xin , WANG Zhong-tang ,et al.Experimental Research on Tensile Test of Tailor-W elded( 1 ) High stress concentrates around the weldingBlanks With Unequal Thickness[ J ] Metal Forning Technology ,line ;2000 ,6( 18 ):10-13.(2) With increasing plastic strain ,the TWB stress [s] ZHANG Fuxiang ,CHEN wei. Reerch on welding Linedistribution is more uniform than the initial status ;Movement for TW B During Square Cup Drawing[ J ]. Metal Form-( 3 ) During the deep drawing TWB process , theing Technology ,2002 ,20( 5 ):33-36.[6r Id Numerical Simulation ofwhole welding line movement is just like a rigid string ,中国煤化工Drawing See[J] JoumalalTYHC NM H G77-78 ,96.