Experimental and FE analysis of submerged arc weld induced residual stress and angular deformation of single and double sided fillet welded joint

Submerged arc welding is well-known for its very high deposition rate and thus the capability to join very high thickness metal pieces in large structural applications. Fillet joints are mostly used in structural applications which can be extensively seen in shipbuilding, bridge construction, house buildings, automobile or any other large structures. Thermal stresses generates in a fusion welded joint due to high temperature gradient, which is the cause of the residual stresses upon cooling followed by the angular deformation and failure of the welded structure. As an effect of the thermal gradient, the induced longitudinal, transverse residual stress & angular distortion can vary in single sided and double sided submerged arc welded fillet joints, during designing & manufacturing welded structures which should be taken into account. The main objective of this paper is to quantify the amount of residual stresses and angular deformation in a fillet welding joint. An elasto-plastic thermomechanical model has been developed for predicting residual stresses. A comparison of the residual stress and angular deformation between single and double sided fillet weld joint has been made. The simulation results reveal that the amount of residual stress present in the single sided fillet weld is more and unbalanced in both side of the center of weld line compared to the double sided fillet weld and the predicted results have been matched with the experiments as well as published literatures.     

Mechanism investigation of welding induced buckling using inherent deformation method

Due to the increasing use of thin plates in lightweight welded structure, welding induced buckling may occur in such thin plate welded structure. In this study, welding induced buckling of thin plate welded structure is investigated using the eigenvalue analysis and elastic Finite Element (FE) analysis based on inherent deformation theory, and the mechanism of welding induced buckling is clarified.Bead-on-plate welding is first examined. Measured out-of-plane welding distortion indicates that saddle type buckling is produced after cooling. Eigenvalue analysis shows the computed lowest buckling mode is the saddle type and the corresponding critical force is less than the applied tendon force evaluated by Thermal–Elastic–Plastic (TEP) Finite Element (FE) analysis beforehand. Using elastic Finite Element (FE) analysis in which all components of inherent deformation are used and also considering initial deflection, out-of-plane welding distortion is predicted with high accuracy compared with measurement. It is also concluded that tendon force (longitudinal inherent shrinkage) is the dominant reason of buckling and it determines the buckling mode, and initial deflection and inherent bending are considered to be disturbances which trigger buckling.Later, a thin plate stiffened welded structure with fillet welded joints is examined. Although welding did not induce buckling of plate fields in bending modes in the considered thin plate stiffened welded structure, the whole stiffened welded structure buckles in a twisting mode, while plate panels remain unbuckled. Eigenvalue analysis gives the twisting buckling mode as the lowest buckling mode. However, in stiffened welded structures, not only tendon force (longitudinal inherent shrinkage) but also transverse inherent shrinkage is responsible for buckling. The good agreement between computed and measured out-of-plane welding distortion shows that the elastic Finite Element (FE) analysis using inherent deformation theory is an advantage of the computational approach to predict welding distortion in large-scale and complex welded structure with enough computational accuracy.     

角焊缝的设计:世界规程比较

通过对比英国、欧盟、美国及中国的钢结构规范对角焊缝的最小和最大焊脚尺寸、焊缝强度取值等的不同规定,发现我国规范不考虑埋弧焊等有利影响、对焊喉尺寸和角焊缝的强度取值偏于保守,欧盟规范对角焊缝设计强度的取值最高。     

赞比亚硫酸贮罐底板焊接变形的控制技术

硫酸贮罐底板直径大、焊缝多、焊接量大,在焊接过程中将不可避免地产生焊接应力和焊接变形。焊接残余应力和变形的存在,会对焊接底板的承载能力和外形尺寸产生不同程度的影响。采用焊接变形控制技术后,可减少底板焊后的变形,释放焊接残余应力,改善焊接质量。自投产以来,至今运行状态良好,实践证明:这种技术方案能满足施工技术要求。     

双相型S22053不锈钢角焊缝连接拉伸试验研究

焊缝连接广泛应用于不锈钢结构生产和装配领域,但目前国内外专门关于不锈钢焊缝连接承载性能的研究较少。为研究国产双相型S22053不锈钢角焊缝搭接接头的承载性能,对6个正面角焊缝连接试件和5个侧面角焊缝连接试件进行了拉伸试验,测得了焊缝连接在拉伸作用下的极限荷载、极限强度等,并对焊缝随荷载的变形情况进行了测量。试验结果表明：正面角焊缝连接试件破坏截面平均角度约29°,并非45°理论值,其极限强度平均值973MPa,焊缝平均变形量为1.139mm。侧面角焊缝连接试件破坏截面平均角度约46°,比较接近45°理论值,其极限强度平均为637MPa,焊缝平均变形量为1.792mm。正面角焊缝连接试件焊缝极限强度为侧面角焊缝连接试件的1.53倍。     

南京麒麟互通匝道桥钢箱梁制作技术

南京麒麟互通匝道桥平面曲线圆弧半径小,弧形制作线型控制难;钢葙梁为全焊结构,采用分段制作,结构焊缝多,焊接变形大.通过对钢箱梁合理的分块,不但减少焊接工作量,而且适宜公路运输,方便制作、架设;采用焊接反变形技术及火焰热矫正,解决板单元焊接变形问题;通过专用预拼装胎架、全站仪测量,较好控制了钢箱梁各分块的整体线型,在制作...     

深圳至中山跨江通道钢桥面板结构疲劳试验研究

正交异性钢桥面板的疲劳开裂问题是制约桥梁工程可持续发展的关键难题,亟需发展具有高疲劳抗力特性的正交异性钢桥面板结构。依托深圳至中山跨江通道项目,在钢桥面板结构中同时引入纵肋与顶板新型双面焊构造细节和纵肋与横隔板新型交叉构造细节两类构造细节,设计9个足尺节段模型,通过模型试验确定了纵肋与顶板传统单面焊构造细节和新型双面焊构造细节、纵肋与横隔板传统交叉构造细节和新型交叉构造细节的疲劳开裂模式和实际疲劳抗力;采用扫描电子显微镜(SEM)确定了不同制造工艺条件下纵肋与顶板焊接细节的初始制造缺陷尺度;采用等效结构应力法确定了两类细节各疲劳开裂模式的疲劳抗力。研究结果表明：纵肋与顶板传统单面焊构造细节的疲劳裂纹起裂于顶板焊根并沿顶板厚度方向扩展,其疲劳抗力为95.1～98.7MPa,新型双面焊构造细节的疲劳裂纹起裂于顶板内侧焊趾并沿顶板厚度方向扩展,其疲劳抗力为108.5～123.2MPa,且在相同加载条件下,双面埋弧焊构造细节的疲劳抗力高于双面焊气体保护焊构造细节的疲劳抗力;传统单面焊构造细节焊根的初始制造缺陷尺度显著大于新型双面焊构造细节焊趾的初始制造缺陷尺度,且双面埋弧焊的初始制造缺陷尺度小于双面气体保护焊的初始制造缺陷尺度,初始制造缺陷尺度的差异是不同制造工艺条件下纵肋与顶板焊接细节疲劳抗力存在差异的主要原因;纵肋与横隔板传统交叉构造细节的疲劳裂纹起裂于纵肋腹板焊缝端部焊趾并沿纵肋腹板扩展,新型交叉构造细节的疲劳裂纹起裂于纵肋底板焊缝端部焊趾并沿纵肋底板扩展,两类构造细节的起裂次数基本一致,但新型构造细节的疲劳裂纹扩展速率远低于传统构造细节的疲劳裂纹扩展速率;纵肋与顶板焊接构造细节和纵肋与横隔板交叉构造细节各疲劳开裂模式的实际疲劳抗力基本位于主S-N曲线±2σ之间。     

上海动车段新槎浦中桥钢桁梁箱体主角焊缝水上焊接工艺研究

上海新槎浦中桥钢桁梁在制作过程中,由于户外作业完成的半成品钢箱梁受到雨水的浸泡,主角焊缝内部积水,且积水很难清除,严重影响焊接质量。针对此突发事件展开工艺研究,制定多种方案,采取先除水后埋弧焊接的措施,经过不断研究摸索,最终解决了问题,并通过无损检测和机械性能检测,确保焊缝质量合格。该技术使角焊缝顺利焊接完成,避免改为全熔透角焊缝焊接工艺,减轻劳动量、降低工程量、节约成本。     

Comparison the capacity of box steel columns,fabricated with groove and fillet welds

Currently, box columns are fabricated by welding plates using fillet or groove welds. According to probable seismic failure mechanism of these columns, their nonlinear behavior in terms of ductility and strength is necessary. In this research, a variety of columns with different welding patterns including groove and fillet welding with various overlap values and weld legs are numerically modeled and their nonlinear behavior is studied in finite element domain by using ABAQUS software. Suitable welding pattern is proposed by evaluation the energy absorption as well as stress distribution and concentration in box section. Results indicate that the section fabricated through groove welding has the best nonlinear performance and in the next priority, the sections with overlap size and weld leg equal to 20 and 80, or 50 and 50 percent of plate thickness, respectively, lead to suitable performance.     

Schweißen von Feinkornstählen und deren Eignung für Offshore‐Windenergieanlagen

Welding of fine grain structural steels and there suitability for offshore wind power plants. The investigations show that the high requirements on the mechanical values of a welded joint can be fulfilled by economical process versions of submerged arc welding. The submerged arc tandem twin welding process is predestined for the production of WPP (wind power plant) because of the high value of melting rate and the small expenditure of equipment. The used filler metal is suitable for the production of welded joints with mechanical values which fulfil safely the requirements. Steel grades produced by the TMCP becoming more and more popular for the producers of wind power generator tower because of there better processing and working properties. In comparison with normalized steel grades the TMCP steel grades have e.g. a lower carbon equivalent and higher toughness properties. With increasing clarity of the standards and of the working direction of the European offshore wind power industry further challenges will be appear for the producers of steel, wind power plants and welding equipment. A close cooperation between al partners is inalienable in that case.     

正交异性钢桥面板顶板竖向加劲肋焊接接头疲劳性能试验研究

正交异性钢桥面板的疲劳问题是目前研究的主要热点之一。该文针对国内钢桥面板顶板竖向加劲肋焊接接头的构造细节,通过振动型疲劳试验机开展了18个试件的弯曲疲劳试验,研究了普通角焊缝和熔透角焊缝在不同加载应力幅下的疲劳性能,分析了焊接接头的应力集中系数,并与有限元分析结果进行了对比,得到了普通角焊缝和熔透角焊缝焊接接头疲劳寿命大小;同时采用BS5400、JSSC、Eurocode 3以及我国钢结构设计规范（GB 50017—2003）规定的S-N曲线对试验结果的疲劳强度进行了评定。研究表明：钢桥面板竖向加劲肋焊接接头熔透角焊缝的疲劳性能总体上优于普通角焊缝,对我国钢桥面板竖向加劲肋焊接接头的开裂前的疲劳性能建议采用BS5400-F2的S-N曲线（35MPa）进行设计和评价;并且两者焊接接头的应力集中系数约为2.4左右,其中熔透角焊缝受到焊接工艺的影响其应力集中系数较大,须在焊接后对其进行焊趾表面处理,以进一步提高疲劳性能。     

城市钢箱梁高架桥球形支座安装施工工艺

城市钢箱梁高架桥球形支座安装主要控制安装方向、高程、位移等;球形支座安装前进行基础复测及支座顶板与钢箱梁底板焊接,焊接采用焊条电弧焊方法,并进行焊前温度不低于200℃预热处理。球形支座安装用钢楔形垫块将下支座板四角调平。球形支座灌浆先灌地脚螺栓孔,灌完24h达到强度后再灌支座底面预留的灌浆层,最后拆除四角钢楔形垫块用环氧砂浆填满垫块位置。钢箱梁卸载后进行焊接垫板与钢箱梁底板焊接,焊接完毕后拆除临时连接件,并安装防尘罩。支座高程允许偏差控制在±3mm以内,支座偏位允许偏差控制在2mm以内。     

Optimization-improved thermal–mechanical simulation of welding residual stresses in welded connections

This paper presents a novel computer-aided computational framework to determine the optimum shape parameters in a welding heat source model using a coupled supervised Gaussian process regression (GPR) and genetic algorithm (GA) approach in estimating the welding residual stresses. The experimental X-ray diffraction (XRD) approach validates the optimization-improved thermal–mechanical simulation method. The validation of the proposed approach includes the welded plates with simple geometry to welded pipe-to-plate and the circular hollow section joints with complex topologies. The optimization-derived shape parameters in a welding heat source model lead to close estimates of the temperature history and the welding residual stresses for these types of welded joints considered in this study.     

Tragverhalten von Kehlnahtverbindungen von höherfesten Feinkornbaustählen

Load Bearing behaviour of fillet weld connections of high‐strength fine grain steel. Latest investigations [1] have proved, that the load bearing capacity of fillet weld connections of thermomechanically rolled fine grain steel S 460 is underestimated in actual design codes [2], [3], [4]. In this article, a possibility of calculating the load bearing behaviour using FE programs is shown. Based on these calculations and the results of large scale tests, the influences of different production processes, different weld materials and the welding parameters on the load bearing capacity of fillet welds are rated.     

Experimental analysis of prestressed thin-walled structures stability

In this paper the results of experimental investigations and numerical calculations of thin-walled plate girders are presented. The objective of this investigation was to determine the effect of prestressing technology based on weld shrinkage of fillet welds joining additional overlay plates welded in the area of the structure tension on their stability.     

改进贴板加强的钢管受弯连接节点试验研究

由于国家游泳中心多面体空间刚架的杆件与节点之间采用全熔透的对接焊缝连接,为避免焊缝脆性破坏先于钢材破坏,实现"强节点弱构件"的设计思想,确保结构具有良好的延性,有必要对焊缝连接节点进行适当加强。采用低周反复加载方法对改进贴板加强的方钢管及圆钢管杆端受弯连接节点进行试验研究。改进的贴板加强方式对4面围焊的矩形贴板作了两方面的改进:贴板形状由矩形改为下部矩形、上部梯形的形式;取消贴板前端的焊缝,由4面围焊改为3面围焊。研究表明,改进贴板加强方式可有效减少由于焊接引起的母材材性改变所带来的不利影响,节点的破坏形式则由钢材拉裂改变为钢管的局部压曲,节点的耗能能力更强、延性更好。     

Verification of possibility for controlling welding distortion generated by laser-arc hybrid welding

For predicting welding distortion and residual stress generated by laser-arc hybrid welding (HYBW) with high accuracy by the 3D thermal elastic-plastic analysis based on FEM, a heat input model considering the dual heat source of HYBW was proposed. By using the proposed model, welding distortion and residual stress generated by HYBW on the general structural steel under several welding conditions, in which the heat input ratio of laser and arc were variously changed, were obtained. Comparing with the results obtained by experiments and analyses, the validity and generality of the proposed heat input model could be verified. The tendency and magnitude of welding distortion varied with the heat input ratio of laser and arc. The results indicated the possibility for controlling welding distortion generated by HYBW with the optimum heat input ratio of laser and arc.     

Cyclic testing of beam-to-column connections with weld defects and assessment of safety of numerically modeled connections from brittle fracture

This paper concerns the assessment of significance of weld defects in beam-to-column connections. Four full-sized beam-to-column connections with weld defects were tested under cyclic loads. When the unfused regions created by partial joint penetration groove welds were reinforced by fillet welds so that the welded joints have a sufficient cross-sectional area, ductile cracks grew stably and, in consequence, the connections showed sufficient deformation capacity. The connections with weld defects at the root of welds sustained a quick extension of ductile cracks and, eventually, failed by brittle fracture. Test results were reproduced well by non-linear FE analyses. Fracture toughness properties of numerically modeled weld defects were evaluated by using a recently developed fracture mechanics approach. The results of evaluation were found to correspond well with test results.     

基于断裂模拟的高温下角焊缝接头承载性能研究

为准确预测火灾高温下正面角焊缝焊接接头的承载性能,结合已有高温下钢结构正面角焊缝焊接接头的拉伸试验数据,采用有限元数值分析方法,对20~700 ℃下20个焊脚尺寸均为12.7 mm的角焊缝焊接接头的断裂模式与实际承载性能进行研究。拟合高温作用下适用于断裂模拟的焊材熔敷金属真实应力-应变关系,标定高温下适用于焊材熔敷金属的剪切断裂模型材料参数,采用试验获得的荷载-位移曲线、断裂破坏模式以及AISC 360-10中的承载力计算方法对数值模拟结果进行验证。研究结果表明：高温作用下角焊缝焊接接头的断裂位置多发生在焊缝区,断裂从焊根部分开始并随荷载的增大向焊脚位置扩展;接头的极限承载力随着温度升高而减小,高温下接头的极限承载力可由断裂面面积及焊材抗拉强度确定;接头在高温作用下（大于500 ℃）的变形量超过5 mm,约为常温作用下的5倍;焊材的剪切断裂模型参数是其抗裂性能的重要参数,也是相应的焊接接头构件变形能力的重要指标,在高温作用下（大于500 ℃）,焊材断裂参数是其常温作用下的4.5倍。     

小口径锥形焊管的制作技术

由于焊接设备的限制,小口径的锥形直缝焊管只能采用单面焊的制作技术,合缝与焊接是其关键制作工序.传统制作工艺采用人工合缝、半自动埋弧焊机进行焊接,焊缝质量不稳定,焊接效率低.改进工艺采用龙门式埋弧焊机,并配备自动合缝装置,可极大地提高焊接质量和焊接效率.目前,锥形管还没有统一的检验标准,在参考相关标准进行质量检验的基础上...