304L不锈钢结构焊接变形分析.pdf

第3 1卷 第1期 2 0 1 0年1月 焊 接 学 报 TRANSACTI ONSOF THE CH I NA WELD I NG I NSTITUTI ON Vol . 31 No. 1 January 2 0 1 0 收稿日期 2008 - 09 - 04 基金项目江苏科技大学先进焊接技术省级重点实验室开放基金资 助项目JSAWT2072 02 304L不锈钢结构焊接变形分析 马坤明, 罗 宇, 王江超 上海交通大学 船舶海洋与建筑工程学院,上海 200030 摘 要针对304L不锈钢材料进行了平板表面堆焊的试验研究和热弹塑性有限元分 析.结果表明,试验和数值模拟结果的一致性验证了计算中所假定的材料高温性能参 数的合理性.在此基础上,应用热弹塑性有限元法对304L不锈钢液化天然气独立液舱 气室与筒体装焊的实例进行研究,成功地预测了结构的焊接变形,为304L不锈钢大型 复杂结构焊接变形的模拟和控制提供了理论依据. 关键词 304L不锈钢;高温性能参数;热弹塑性有限元;焊接变形;大型复杂结构 中图分类号 TG404 文献标识码 A 文章编号 0253 - 360X2010 01 - 0055 - 04马坤明 0 序 言 304不锈钢美国AST M标准属于一种奥氏体 不锈钢,而304L作为一种新材料,是碳含量较低的 304不锈钢的变种,即超低碳级不锈钢 [1 ] ,由于其低 温下的优异的断裂韧性以及耐腐蚀性,所以被广泛 应用于低温的LNG liquefied natural gas独立液舱 等工程结构中. 奥氏体不锈钢本身具有较高的热膨胀系数和较 低的热传导系数,在焊接过程中产生大量的收缩、 变 形和残余应力 [2 ]. 过大的超差变形将会导致装配达 不到工艺要求和降低结构的承载能力,所以对其焊 接变形的预测分析就显的尤为重要了.一些学者对 304不锈钢进行了研究,但目前还没有发现有关 304L焊接变形研究的文献,主要是因为304L是一 种新型不锈钢材料,在高温下的物理性能参数和力 学性能参数都比较缺乏.文中通过试验和热弹塑性 有限元模拟相结合的方法,确定出计算所需要的 304L不锈钢高温性能参数,并将其应用于大型复杂 结构LNG独立液舱的焊接变形预测中. 1 堆焊试验 1. 1 试验材料和物理模型 试验采用奥氏体不锈钢304L,其主要化学成分 及力学性能见表1. 表1 304L不锈钢主要化学成分及力学性能 Table 1 Main chem ical components and mechanical properties for 304L stainless steel CCrNi 屈服强度 ReL/MPa 抗拉强度 Rm/MPa 断后伸长率 A ≤0. 03018～208～12≥240≥55040 平板表面堆焊试件的尺寸为350 mm270 mm 15 mm,堆焊位置和焊接变形测量点分布如图1 所示. 图1 堆焊位置和变形测量点分布mm Fig11 Po sition of p late surfacing welding and distribution of deation m easuring point 1. 2 试验设备和焊接工艺 试验设备主要包括电焊机,小车和试件.试验焊 接过程如图2所示. 焊接方法采用钨极氩弧焊,焊接工艺参数见 表2. 56 焊 接 学 报第31卷 图2 焊接过程演示图 Fig12 W elding process demonstration 表2 焊接工艺参数 Table 2 W elding parameters 编号 电压 U/ V 电流 I/ A 焊接速度 v/ mmmin - 1 热输入 E/ Jmm - 1 11010090533 21115090878 313. 9175120974 415. 22261201 373 513. 3200901 421 616. 52751201 814 717. 72751002 338 816. 5275802 722 916. 2275603 566 1017. 4275504 594 2 堆焊的热弹塑性有限元分析 2. 1 304L的材料性能参数 304L不锈钢常温下的物理性能和力学性能参 数参见文献[3 ].由于304L是一种新型不锈钢材 料,高温下的参数比较缺乏,但由于304L和304相 比主要是含碳量更低了,常温下的参数比较接近,所 以通过对304高温参数 [4, 5]进行合理的修正来初步 确定304L高温下的材料性能参数. 2. 2 平板堆焊模拟 应用热弹塑性有限元法 [6 ]进行平板表面堆焊 模拟,焊接工艺参数见表2.表2中的热输入E为模 拟计算的热输入,且EηU I/v,其中 η为计算中所 采用的电弧热效率,取0. 8.采用间接耦合法 [7 ] ,利 用ANSYS软件运用其热分析功能计算整个焊接过 程温度场,并将温度场的计算结果作为热载荷进行 结构的力学分析. 首先应用初步确定的材料参数进行计算.为减 少计算量,可先选取3或4个热输入相差较大的工 艺参数计算,观察变形趋势是否与试验结果相符合, 如果不符合就要重新检查模型.在保证变形趋势相 同的条件下,通过反复调整和修正材料参数,最终确 保模拟变形值与试验测量结果得到较好的吻合. 通过对10组工艺参数进行模拟和对试验测量 结果进行整理,得到最终焊接变形与焊接热输入的 关系曲线图3. 图3 焊接变形与热输入的关系曲线 Fig13 Relation between welding defo r m ation and heat 由图3可见,模拟曲线和试验曲线的变化趋势 和数值大小都非常接近,而计算中采用304L不锈钢 的物理性能和力学性能如表3所示,因此可以认为 所假定的材料性能参数是合理的. 3 应用实例 气室与筒体是LNG独立液舱的重要组成部分, 材料采用304L不锈钢,其主要尺寸为筒体内直径 12. 3 m,厚度18. 8 mm;气室外直径3 m,焊接部位 的厚度35 mm;在筒体与气室焊接部分,有一层壳体 补强板,厚度15 mm.应用热弹塑性有限元法对气 室与筒体的装焊行为进行了分析,通过采取一系列 减少计算量和加强收敛的措施,成功的预测了结构 的焊接变形. 3. 1 有限元模型和边界约束 由于考虑到对称性,所以只需取模型的一半建 标准分享网 w w w .b z f x w .c o m 免费下载 w w w . b z f x w . c o m 第1期马坤明,等 304L不锈钢结构焊接变形分析57 表3 304L不锈钢的理物性能和力学性能 Table 3 Physical and mechanicalp roperties of 304L stainless steel 温度 T/℃ 导热系数 λ/ Wm - 1℃- 1 比热容 cp/ Jk g- 1℃- 1 密度 ρ/ kgm - 3 线膨胀系数 α/ 10- 6℃- 1 弹性模量 E/GPa 泊松比 μ 屈服强度 ReL/MPa 2014. 64717 90216. 51940. 28240 20018. 15017 84617. 21880. 28230 40020. 55357 75017. 91630. 28138 60023. 15697 65318. 61440. 2855. 3 90027. 36217 52019. 59. 40. 286. 1 1 10029. 96597 42619. 72. 00. 284. 7 1 40033. 47307 24120. 00. 50. 282. 5 模.在不影响计算精度的前提下,为了减少计算量, 采用非均匀的过渡网格,在焊接热影响区域,采用相 对较细密的网格划分,远离焊缝的区域则采用相对 稀疏的网格划分.筒体和气室都采用实体单元 SOL I D70,而筒体内侧的T形肋骨部分可以利用等 惯性矩、 等抗弯刚度原则 [8]采用带厚度的平面应力 单元PLANE55建立.筒体与气室装焊的有限元模 型如图4所示,单元总数为16 803,节点总数为 22 194. 图4 有限元模型 Fig14 Finite elem entmodel 温度场计算过程中,结构外表面存在对流和辐 射换热,给定一个总的换热系数,把对流和辐射换热 同时考虑进去,忽略相变潜热的影响.结构分析时, 对称面yOz上加对称边界约束,同时约束A节点y 方向自由度,B节点y, z方向自由度, C节点z方向 自由度.限制了结构的刚体位移和转动. 3. 2 焊接工艺 结构采用双面焊的焊接形式,具体焊接工艺参 数见表4. 3. 3 热弹塑性有限元分析 由于在焊接阶段,温度梯度大,所以要采用较小 表4 焊接工艺参数 Table 4 W elding parameters 电压U/ V电流I/ A焊接速度v/ mmmin- 1效率 η 23～28165～175140～27080 的时间步长,保证计算精度.而焊接结束冷却阶段, 温度梯度较小,可采用相对较大的时间步长,以减少 计算量.影响热弹塑性有限元计算收敛性的因素有 很多,如网格划分质量的好坏程度,材料高温参数处 理的是否正确,以及约束施加的是否合理都会影响 到收敛性和计算精度.在结构分析中,激活大变形 效应,加强收敛和保证精度.打开自动时间步长,激 活二分法,有助于加快计算速度和加强收敛.另外 加热温度不要过高,达到熔点即可,否则就会引起网 格发生高度屈曲变形最终导致不收敛.最好采用递 变载荷加载,有助于加强收敛.运用ANSYS参数化 编程语言APDL编写命令流程序,在配备最新CPU 的服务器上,完成了结构的热弹塑性有限元计算. 结构主要变形发生在y方向,即气室的下塌变 形,最大变形为4. 217 mm,满足实际的装配施工要 求,焊接变形如图5所示. 图5 y方向的焊接变形 Fig15 W elding deation in y direction 最大等效残余应力位于焊缝中心处,大小为 w w w . b z f x w . c o m 58 焊 接 学 报第31卷 309. 857 MPa,并沿着环向焊缝向两侧逐渐降低,Mi2 ses等效残余应力分布如图6所示. 图6 M ises等效残余应力 Fig16 M ises equivalent residual stress 4 结 论 1基于试验结果和数值模拟结果的比较分 析,最终确定出计算所需要的304L不锈钢的一组合 理可靠的高温性能参数. 2应用热弹塑性有限元法很好的预测了气室 与筒体装焊的焊接变形和残余应力分布,为304L不 锈钢大型复杂结构焊接变形的模拟和控制提供了理 论依据. 参考文献 [1] 陈连山,陈兵辉,安金平.304L不锈钢氩弧焊接工艺特点及 常见缺陷的防治措施[J ].石油工程建设, 2008, 343 49 - 50. Chen Lianshan, Chen Binghui, An Jinping .Technological fea2 tures of 304L stainless steel argon arc welding and defect preven2 tion measures[J ]. Petroleum Engineering Construction, 2008, 34 3 49 - 50. [2 ] 周金枝,钟 斌.用热处理方法消除奥氏体不锈钢焊接残余 应力[J ].湖北工业大学学报, 2007, 224 88 - 90. Zhou Jinzhi, Zhong Bin.Elimination welding residual stress in austenite stainless steelwith heat treatment[J ]. Journal of HubeiUniversity of Technology, 2007, 224 88 - 90. [3 ] 国家标准GB /T 20878 - 2007不锈钢和耐热钢牌号及化学成 分[ S].北京中国标准出版社, 2008. [4 ] 李建强. 304不锈钢激光焊接的建模与仿真[D ].天津天津 大学, 2004. [5 ] 蒋文春,巩建鸣,陈 虎,等.SS304半管夹套焊接部位残余 应力三维有限元模拟[ J ].焊接学报, 2006, 27 10 77 - 80. JiangWenchun, Gong Jianming, Chen Hu,et al. 32D finite ele2 ment analysisofwelding residual stress for half2pipe jacketmade of 304 stainless steel[J ].Transactions of the ChinaWelding Institu2 tion, 2006, 2710 77 - 80. [6 ] 薛忠明,曲文卿,柴 鹏,等.焊接变形预测技术研究进展 [J ].焊接学报, 2003, 243 87 - 90. Xue Zhongming, QuWenqing, Chai Peng,et al. Review on pre2 diction ofwelding distortion[J ].Transactions of the China Weld2 ing Institution, 2003, 243 87 - 90. [7 ] 张朝晖. ANSYS热分析教程与实例解析[M ].北京中国铁 道出版社, 2007. [8 ] 谢 雷,罗 宇,谢志勇,等.基于固有应变的大型焊接结构 变形的预测[J ].焊接学报, 2004, 25 2 107 - 110. Xie Lei, Luo Yu, Xie Zhiyong,et al. Prediction of defor mation of largewelding fabrication based on inherent strain[J ]. Transactions of the ChinaWelding Institution, 2004, 25 2 107 - 110. 作者简介马坤明,男, 1983年出生,硕士研究生.主要从事焊接 数值模拟方面的研究工作.发表论文1篇. Em ailkunming - ma2007163. com 标准分享网 w w w .b z f x w .c o m 免费下载 w w w . b z f x w . c o m 2010,Vol . 31,No. 1TRANSACTI ONS OF THE CH I NA WELD I NG I NSTITUTI ONⅢ sistance of Fe2C2Cr2V hardfacing alloyswas excellent . Dispersed primary carbidesofM7C3with the size of 15225 micron can effec2 tively impede the micro2cutting movement of abrasive particles and deliberately improve abrasion resistance of the hardfacing al2 loys . Key words abrasion resistance; primary carbide; orient2 ational; hardfacing; high chromium Effects of RE oxide and alloy elements on m icrostructure of hardfacing metal L I Da1, YANG Yulin2, L I U Ligang 1 , YANG Qingxiang 1 , GU Xinsheng 1 , ZHANG Jiazhen1 1. State Key Laboratory of Metastable Materials Science 2. School of Mechanical Engineering,Yanshan University, Qin2 hangdao 066004, Hebei, China. p 37 - 40 Abstract The microstructures of the hardfacing speci2 mens for large gear were observed by optical microscopy OM and the matrix phase of the hardfacingmetalswas determined by X2ray diffraction XRD. Meanwhile, the fractographs and in2 clusionswere analyzed by scanning electron microscopy SEM with energy dispersive spectrum EDS.The results show that, the microstructure of the hardfacingmetal ismainly composed of the fine acicular ferrite. The fractograph of the specimenwith ad2 dition rare earth RE oxide Ce2O3 and Cr, Mo, Ni element in electrode coating is uni and fine dimple addition. Howev2 er, the microstructure is composed of coarse acicular ferrite and pearlite and the fractograph is composed with dimple and quasi2 cleavage in the specimen without RE oxide.The inclusions be2 come spherical and distribute in hardfacingmetal dispersively by adding RE oxide in electrode coating, their sizes are smaller than 6μm. Key words RE oxide;hardfaceing metal; microstruc2 ture; inclusion M odeli ng and si mulation of position servo control for shear2 flash butt welding machi ne based on LQR WANG Hong2 wen, L I Yang, J IHailiang, WANG Yongwei School of Electri2 cal Engineering position servo control; AMESi m Feature extraction of penetration arc sound in M IG welding via wavelet packet frequency2band energy L I U Lijun1, 2, LAN Hu2, WEN Jianli 2 , YU Zhongwei 2 1. Ningbo Institute of Technology,Zhejiang University, Ningbo 315100,Zhejiang, China; 2.School ofMaterial Science arc sound; wavelet trans; frequency2band energy; feature extraction Effect of peak pulse voltage on metal transfer and ation of weld in double2wire pulsed M IG welding Niu Yong 1 , Xue Haitao2, LiHuan3, Zeng Zhoumo11. State KeyLaboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin 300072, China; 2.School ofMaterials Sci2 ence 3.School ofMaterials Science peak pulse volt2 age; metal transfer; for mation ofweld Analysis of weldi ng deation of 304L sta inless steel struc2 ture MA Kunming, LUO Yu, WANG Jiangchao School of Naval Architecture,Ocean and Civil Engineering,Shanghai JiaotongUniversity, Shanghai 200030, China. p 55 - 58 w w w . b z f x w . c o m ⅣMA I N TOPI CS,ABSTRACTS material properties un2 der high temperature; ther mal elastic2plastic FEM; welding de2 ation; large complicated structure W elding behavior of two current phase relations for twin2 wire pulsedMAG welding WEN Yuanmei 1, 2 , HUANG Sh2 isheng 1 , WU Kaiyuan1, LAO Zhengping 1 1. School ofMechan2 ical Engineering, South China University of Technology, Guang2 zhou 510640, China; 2.Faculty of Ination Engineering, Guangdong University of Technology, Guangzhou 510006, Chi2 na. p 59 - 62, 66 Abstract Based on the high2speed video system with e2 lectrical signals analyzer in synchronous,the electrical signals and the photographs of molten droplet under certain welding pa2 rameters were collected,the electrical arc shape and droplet transfer pattern of welding process in twin2wire pulsed MAG weldingwere studied.It is observed thatwhen the pulse current rted on the frontwire and the rearwire by turns, the shape of arcs presents the clock cover , and has no influence on each other . When the pulse current rted on the front wire and the rearwire in phase, the arcs attract each other and the arc is in2 corporated as a peach.The weld appearance of the synchronous pulse current is good and the concomitant is great noise and smog .The weld appearance of the alternating pulse current is tolerable. Key words pulsed MAG welding;t win2wire;droplet transfer; shape of arc I nterpolation algorithm and si mulation of auto2weldi ng sad2 dle2shaped nozzle of heavy pressure vessels DUAN Tiequn1, SH I Guangyuan1, YU Dan2, YANG Kefei 2 1. Harbin University of Science and Technology, Harbin 150080, China; 2. HarbinWelding Institute, Harbin 150080, China.p 63 - 66 Abstract According to the welding processes of nozzle of heavy pressure vessels, this paper introduced the structure and principle of the automatic welding machine, and also presenteed the mathmetical model and si mplified interpolation algorithm which used two collaborative axis to for m a space fitting saddle2 shaped welding bead.The si mulation results indicate that the two2axis interpolation algorithm can meet the requirements of the automatic welding . Key words heavy pressure vessels;automatic welding machine; interpolation algorithm; simulation M icrostructure and mechan ical property of Ag2Cu2Ti fillers added with rare earth lanthanum YANG Changyong, XU Jiuhua, D I NGWenfeng, FU Yucan, CHEN Zhenzhen Jiangsu KeyLaboratory of Precision and Micro2manufacturing Technolo2 gy, Nanjing University of Aeronautics Ag2Cu2Ti filler; microstruc2 ture; mechanical property Effects of applied longitudi nal magnetic field on plasma arc hardfaci ng m icrostructure and property L I U Zhengjun, SONG Xingkui, SHAO Dawei, ZHAO Qian, ZHANG Shixin, CHENGMinghua Materials Science and EngineeringAcademy, ShenyangUniversity of Technology, Shenyang 110023, China. p 71 - 74 Abstract To control the shape and distribution of hard phase,longitudinal magnetic field was applied during plasma hardfacing of Fe5 alloy .The hardness, wearing, microstructure and X2ray diffraction analysis of the hardfacing layerwere tested aswell as the structure and property of the handfacing layer of the powder .The results showed that the layer had higher hard2 ness and betterwearingwith magnetic field than the layer ed withoutmagnetic field.The properties of hardfacing layer were optimum when the magnetic field currentwas 3A and the micro2 structures of alloy hardfacing layer obtained ideal hard phase such as Cr7C3, CrB ect and solid solutionαandγwere refined sufficiently . Key words plasma arc surfacing welding;magnetic field; hard phase Perance of DC plasma arc i n external transverse alter2 nating magnetic field MENG Jianbing, XU Wenji, WANG Xuyue, SONGWenqing KeyLaboratory for Precision and Non2 traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning, Chi2 na. p 75 - 79 Abstract Two mathematicalmodels are developed to de2 scribe the oscillating amplitude of the plas ma arc along the metal surface and the heat flow density distribution ofplas ma arc on the metal surface respectively .The behavior of plasma arc jet under an external transverse sinusoidal alternating magnetic field i m2 posed perpendicular to the plasma current is analyzed theoretical2 ly, and the effect of process parameters such as gas flow rate, arc current, magnetic flow density and the distance from the noz2 zle outlet to the anode workpiece on the for m and distribution of 标准分享网 w w w .b z f x w .c o m 免费下载