拘束条件对薄板T形接头双光束激光焊接变形的影响

采用单元温度对单元进行生死控制的有限元计算方法研究了拘束条件对2.5 mm厚铝锂合金5A90薄壁T形接头双光束激光焊接变形的影响,拘束条件包括对筋板施加和对底板施加两类,约束在焊接过程中施加,焊后冷却到室温去除.筋板拘束条件施加在筋板顶部和侧面,对比了施加与不施加约束两种情况,该两种情况连续焊接之前都采用点固焊对筋板进行固定.底板拘束条件通过在T形接头两侧设置压块对底板施压来实现,研究了压块与焊缝不同距离对焊接变形的影响.最后进行了试验验证.焊接过程中对筋板施加约束有利于减小焊接过程中及焊后筋板变形.底板纵向约束影响T形接头焊件挠曲变形的大小和方向,对角变形影响不大.焊接过程中对底板施加y向约束,有利于减小角变形.对底板加纵向约束与不加纵向约束两种情况进行了试验验证,变形方向及变形量最大值的计算结果与试验结果符合.     

T形接头双光束激光焊变形计算方法

以厚度为2.5 mm的铝锂合金5A90薄壁T形接头双光束激光焊变形为研究对象,针对焊缝金属熔化及凝固引起的材料力学行为变化,考虑筋板与底板之间连接的实现过程,开发了双光束激光焊单元生死温度判别法,焊接过程中以单元瞬态温度为判据,对单元动态杀死和激活;对比了采用与不采用单元生死温度判别法的焊接变形计算结果,该两种计算方法在材料参数、几何模型、边界条件及初始条件等方面都完全相同.结果表明,是否采用单元生死温度判别法对T形接头双光束激光焊变形的计算结果有显著影响,并对这种影响进行了分析.     

薄板铝合金搅拌摩擦焊接头变形情况分析

采用数值模拟的方法对薄板铝合金搅拌摩擦焊接头的变形特征进行分析,并与实际接头的变形情况进行对比.结果表明,薄板铝合金搅拌摩擦焊的接头的变形成非对称形式,大变形区域主要出现在焊缝的前进侧,这种非对称变形主要是由于搅拌头对工件直接施加的机械力造成的.焊缝两侧固定点上的变形特征显示,后退侧在焊接过程中会出现剧烈波动,表明后退侧的稳定性低于前进侧.接头应力分布特征显示高应力区出现在焊缝的结束位置,x-y方向的剪切应力是影响终接头应力分布的主要原因.     

Numerical analysis of joint temperature evolution during friction stir welding based on plastic deformation heat

3D numerical model for friction stir welding (FSW)was developed by using ABAQUS software considering the plastic deformation heat.Effects of the rotation and welding speeds on the temperature field of FSW 2024-T3 aluminum alloy were systematically investigated.The temperature measurement was performed to validate the reliability of the model.The simulation results are in good agreement with the experiments.Results show that changing the rotation speed has no influence on the time for reaching the peak temperature at certain point in the workpiece at a constant welding speed.While increasing the welding speed has significant effect on the time for reaching the peak temperature but the value of peak temperature changes little.     

分段退焊对角接接头焊接残余应力及变形的影响

基于热-弹塑性有限元理论,以Abaqus软件为平台进行角接接头焊后残余应力及变形的分析,采用分段移动热源模型并利用Fortran语言开发热源子程序,分别采用直通焊和分段退焊两种方式进行角接接头焊接温度场、残余应力及变形的数值模拟分析.结果表明:横向变形是角接接头最主要的变形;角接接头焊接在焊缝端口处的残余应力为压应力,...     

Metallographic analysis of the welded joint in automatic argon-shielded non-consumable electrode welding

The results of investigation of the quality of welded joints produced by argon-shielded consumable electrode welding in USKT automatic welding equipment are presented. The metallographic analysis of the welded joint was carried out using a PMT-3 microhardness metre and the Altami Studio 3.2 image analysis software.     

BHW35锅炉汽包纵缝埋弧自动焊接工艺

分析了BHW35锅炉用钢的焊接性能,采用埋弧自动焊接设备进行了BHW35超高压锅炉汽包纵缝的焊接工艺试验,使用金相显微镜观测了母材和焊接接头的微观组织。结果表明,母材和热影响区组织为铁素体与贝氏体,熔合线处微观组织为贝氏体,焊缝微观组织为少量铁素体与贝氏体。进行了常温、350℃高温的焊接接头拉伸试验,弯曲角度为100°的弯曲试验,近缝区、焊缝区冲击试验。试验结果表明,试验结果符合BHW35超高压锅炉汽包纵缝焊接工艺要求,制订的焊接工艺可行。     

焊接能量对铝/铜超声波焊接接头显微组织的影响

进行了1 mm厚铝/铜异种金属超声波焊接试验研究,分析了不同焊接能量输入对接头形貌、接合区塑性变形、原子扩散的影响.结果表明,工件在高频振动作用下,连接界面间会发生漩涡状塑性变形,形成局部机械自锁,有助于实现超声波接头的有效连接.焊接能量较小时,结合区域塑性变形量小,局部区域无法形成连接;焊接能量过大时,接合区域会出现空穴.SEM和EDS分析表明,能量过高时(2000 J),接触界面区域会形成薄金属间化合物层,其主要成分为Al₄Cu₉.     

应用三维激光扫描法测量板材的焊接变形

提出一种应用非接触式三维激光扫描仪测量对接试样焊接变形的新方法．在板材上钻孔并放置钢珠用于精确定位,焊接前后应用激光扫描仪对板材和钢珠进行扫描,输出相应的点云文件．应用逆向工程软件Imageware对构件焊接前后的点云文件进行分析和处理,最终得到钢珠球心在焊板上的垂直距离的点的三维坐标．结果表明,该方法解决了由于高温带...     

高强钢低匹配等承载对接接头焊接残余应力调匀能力

借助有限元软件研究了高强钢对接接头中焊接残余应力的调匀情况.结果表明,因母材塑性储备不足,所有接头焊后横向、纵向拉伸峰值应力均在焊接残余应力的基础上不断增加,但接头各区域应力增速不同,最终残余应力均未完全调匀.低匹配静载ELCC接头高塑性、低屈强比的盖面焊道位于高值残余应力所在的焊缝及近缝区母材表面并分担载荷,使该区应力增速放缓,故其残余应力调匀能力优于等匹配接头.考虑焊接残余应力的ELCC接头静载失效更可能发生在母材区,这与ELCC接头的设计目标相符.明确了静载ELCC设计可以忽略焊接残余应力的影响.     

箱型梁焊接变形和应力三维数值模拟

利用有限元分析手段模拟箱型梁结构吊臂的焊接过程,得到吊臂的焊后变形和残余应力分布,采用Metra SCAN激光扫描和盲孔法进行试验验证。结果表明:整体变形趋势为向内收缩,焊缝位置附近上翘变形,峰值位置位于起收弧位置,最大变形量1.66 mm;焊缝位置附近残余应力大,应力峰值为459.9 MPa。模拟结果与试验结果误差控制在0.5 mm以内,仿真结果与盲孔法测量结果吻合较好,误差为26.1%,满足工程应用要求,证明了模拟结果的准确性。     

爆炸焊接波状结合区塑性变形机理的计算分析

爆炸焊接结合区产生大的塑性变形及波状结合,是爆炸焊接工艺的主要特征,也是实现良好冶金结合的必要条件。但是,塑性变形及波状结合的形成机理尚不明确。该文引入牛顿应力公式到弹塑性模型,以近似描述结合区材料行为,建立了连续介质模型,对波状结合区的塑性变形及爆轰速度对塑性变形的影响进行计算分析,并与试验结果对比。结果表明,结合界面呈波形,结合区材料产生大量的塑性变形,并且向界面集中,变形集中的区域沿爆轰方向由宽变窄,材料变形量逐渐增大;随着爆轰速度的增大,界面变形区域扩大,且变形量增大。     

基于固有应变法的转向架构架焊接变形数值模拟

使用SYSWELD中的固有应变法对转向架构架进行有限元分析。采用三种不同焊接方向的方案对构架变形进行数值模拟,模拟得到每种方案下构架各方向上的焊接变形。结果表明,使用固有应变法能够对大型构件进行焊接模拟;不同方向下的焊接变形趋势一致,但在不同位置上构架的变形不相同;可以设计适当的焊接方向,使产生的变形和弯曲减小。     

Three dimension simulation analysis of the interpass stress and deformation during multipass welding

It has been widely studied about the final residual stress and deformation in muhipass welding of thick weldments. But there is a lack of a clear understanding of the interrelationship of interpass stress and deformation during multipass welding. In this study, a three dimension numerical model of a sixteen-pass double V-groove welded joint with 50 mm plate is developed to compute the stress field and deformation by using multiple CPU parallel processing technology. The following factors such as the non-linear of temperature, heat radiation, filling of material step by step and so on are considered. Distribution and evolution law of welding stress in the transverse and longitudinal section is analyzed in this paper, and the interpnss stresses are studied also. At the same time the evolution course of angular deformation amount is analyzed, and the experimental results show that the calculated resuhs accord with the measured results of angular deformation.     

弹塑性变形对不锈钢焊接构件低温时效的影响

对硅单晶炉炉盖内壁发生的腐蚀渗漏做了模拟试验。将塑性变形后经过不同温度低温时效，再对进行弹性变形的试样做了耐腐蚀能力的对比检验。结果表明，随时效温度升高，腐蚀裂纹没有减少反而增多，因此，经冲压或卷制造成大比例弹性变形的奥氏体不锈钢构件不宜进行300～450℃的低温时效处理。     

7A52铝合金双丝焊接头的组织与性能

采用5A56焊丝对7A52铝合金进行双丝气体保护焊,对焊接接头的力学性能和显微组织进行了研究。结果表明,7A52铝合金焊接性能较好。因焊丝合金化学成分和结晶过程的影响,焊缝处是合金接头的薄弱环节。对于中厚7A52铝合金板,采用双丝气体保护焊方法可得到优良的焊接接头。     

Numerical simulation of the welding deformation for the side sill of the bogie frame based on local-global method

Considering the limitation of computational capacity, a new finite element solution is used to simulate the welding deformation of the side sill of railroad car＇ s bogie frame based on the local-global method. Firstly, a volumetric heat source defined by a double ellipsoid is adopted to simulate the thermal distributions of the arc welding process. And then, the local models extracted from the global model are computed with refined meshes. On these bases, the global distortions of the subject studied are ascertained by transferring the inner forces of computed local models to the global model. It indicates that the local-global method is feasible for simulating the large welded structures by comparing the computed results with the corresponding actual measured values. The work provides basis for optimizing the welding sequence and clamping conditions, and has theoretical values and engineering significance in the integral design, manufacturing technique selection of the bogie frame, as well as other kinds of large welded structures.     

高温屈服极限对高强钢焊接变形及残余应力影响的仿真研究

由于缺乏材料的高温数据,进行焊接仿真时所取的高温屈服极限通常有差异。采用双椭球热源模型,对某高强度结构钢的高温屈服极限设计了五种方案进行焊接仿真计算,研究了高温屈服极限对焊接变形和残余应力的影响规律。结果表明:高温屈服极限差异对焊接变形与焊接残余应力有不同的影响;高温屈服极限差异对变形影响较大,越靠近焊缝影响越明显;对残余应力影响较小,仅在近缝区的局部区域产生影响。焊接变形与残余应力均随高温屈服取值的增大而增大。     

EO反应器20MnMoNb特厚度管板拼焊残余应力与变形有限元模拟

利用有限元ABAQUS软件,对国产EO反应器20MnMoNb特厚度管板拼焊制造过程进行有限元模拟,得到了390mm厚的特厚板对接焊残余应力与变形的分布规律．焊接采用双U形坡口,两面交替焊接,并在焊缝两侧的板面上施压4500kN的配重以限制管板的变形．结果表明,特厚度管板焊后在钢板内部为残余压应力,而靠近两外表面,特别是在焊缝及热影响区内,为较大的残余拉应力．施压配重的方法有效地限制了管板的翘曲变形,且施压配重的重量越大,板的变形程度越低,但是变形被限制的同时也增加了板内的残余应力,配重重量的选择需要兼顾其对变形和应力两者的共同影响．     

Finite element analysis of controlling the TC4 thin plate weldment wave-like deformation by welding with impacting rotation

The new technology of welding with impacting rotation is put forward to decrease the wave-like deformation of the TC4 thin plate weldment.The thermal stress and strain are vital to understand the mechanism of controlling the wave-like deformation.In order to know the development of internal thermal stress and strain,finite element method is utilized for the stress and strain are difficult to be investigated by experimental methods during the welding process.Temperature field,thermal stress evolution and distortion of thin plate are compared with the test results such as weld thermal cycle,residual stress sectioning measurement,and the deflection of the thin plate respectively.By the finite element analysis and test results verification,the mechanism of the technology to control the wave-like deformation is brought forward,non-uniform thermal elastic strain between compressive plastic region and elastic extensive region is diminished by a certain amount of extensive plastic deformation by welding with impacting rotation process.