磁控Plasma-FCAW水下复合焊工艺焊缝成形分析

磁控等离子-药芯焊丝电弧复合焊（plasma-flux cored arc welding,Plasma-FCAW）作为一种新型水下高效焊接方法被提出,通过特殊焊炬结构设计实现了两种独立焊接工艺的优势互补. 针对复合焊接工艺中由于电源极性不同引起的电弧排斥问题,设计了外部磁场用于调控两个电弧间的耦合程度,并研究了主要工艺参数对Q355B钢水下焊缝成形及其截面几何特征的影响. 结果表明,施加的外部磁场能够有效改善复合焊接过程及焊缝成形的稳定性;药芯焊丝电弧焊（flux cored arc welding,FCAW）电压对水下复合焊接过程稳定性具有显著影响;等离子电流和FCAW电弧电压对焊缝熔深影响较大且等离子电流与熔深间呈近似线性关系;相比于水下FCAW工艺,复合焊工艺焊接熔深提升超过40%,具有更高的焊接效率和焊接稳定性.     

双丝串列电弧焊焊缝成形的试验分析

将旋转电弧传感器和双丝串列电弧焊结合起来,开发了旋转电弧引导的、两个电弧在同一个熔池上燃烧的双丝串列电弧焊方法,对其焊缝成形工艺进行了研究.分析了焊接电流、焊接电压、双丝间距、电弧旋转等参数对焊缝成形的影响.结果表明,随着焊接电流的增大,熔敷速度增加,焊缝成形系数呈现先增大后减少的变化规律.而焊接电压的增大则会使焊缝成形系数略有减小.对双丝间距的研究发现,当间距为15 mm时,焊接质量较好.与普通双丝串列焊相比,前置电弧旋转时熔池底部变得平坦,最大熔深有所减小,平均熔深有所增加,这将有助于减少焊缝的应力集中.与单丝旋转电弧焊相比,焊接熔敷速度显著增大,有效避免了高速焊接时的咬边现象.     

激光-数字化精确控制短路过渡电弧复合热源焊接技术——一种可取代TIG填丝焊的高效焊接新方法

提出了激光-数字化精确控制短路过渡电弧复合热源焊接新方法.以CMT(Cold Metal Transfer)电弧焊和激光-CMT复合热源焊接为例,利用304不锈钢平板堆焊,对比分析了CMT电弧焊及激光-CMT电弧复合热源的焊缝成形特点,研究了在采用纯Ar保护气体焊接304不锈钢时的激光-CMT电弧复合热源焊接过程稳定性、飞溅、焊缝成形特征、焊接效率及焊接接头的力学性能,并将试验结果与304不锈钢TIG填丝焊进行对比.分析结果表明,纯Ar保护激光-CMT复合热源焊接接头的综合力学性能与TIG填丝焊接头的综合力学性能相当,但焊接效率可以提高5倍,因此在不锈钢和镍基合金等高性能金属材料的焊接中,用纯Ar保护的激光-CMT电弧复合热源焊接取代TIG填丝焊具有可行性.     

机器人MAG焊工艺参数对焊缝成形的影响

采用机器人MAG焊方法进行平敷焊焊接试验,研究机器人MAG焊金属快速成形过程中重要焊接工艺参数对焊缝成形的影响。采用单因素试验方法,分别试验焊接电流、焊接电压、焊接速度、干伸长对焊缝成形的影响,获得了各不同工艺参数对焊缝几何尺寸(焊缝宽度、余高、熔深)的影响规律。试验结果表明,焊接电流、焊接电压、焊接速度对焊缝几何尺寸的影响显著,干伸长对焊缝几何尺寸的影响较小。通过改变各工艺参数可对焊缝几何尺寸进行微调。     

Nd:YAG激光+CMT电弧复合热源横焊工艺参数对焊缝形貌的影响

以304不锈钢为对象,借助横焊焊缝横断面图像来分析Nd:YAG激光+CMT电弧复合热源横焊焊缝横断面的成形特征,研究了Nd:YAG激光+CMT电弧复合热源横焊过程中焊接工艺参数对焊缝横断面形貌的影响.结果表明,在Nd:YAG激光+CMT电弧复合热源横焊中,焊接工艺参数对横焊焊缝横断面形貌的影响显著;Nd:YAG激光加入CMT电弧焊中明显提高了复合焊缝以及复合焊中CMT焊缝的熔深;采取适当的焊接工艺参数(小的光丝间距、大的激光功率、小的焊接速度、适合的离焦量以及小的或大的CMT功率)可以避免熔池机械式叠加和焊缝横断面错位现象,使得焊缝成形良好.     

弧焊机器人焊接姿态与工艺参数联合规划

在现有Motoman UP20弧焊机器人系统上进行二次开发,将人工神经网络技术成功地应用于弧焊机器人焊接姿态与焊接工艺参数的联合规划中.利用MATLAB神经网络工具箱对试验数据进行训练和仿真.凭借人工神经网络自学习功能,建立了焊接姿态与焊接工艺参数联合规划数据表.利用MATLAB软件编制程序,自动提取典型的马鞍形焊缝几何位姿,结合已有数据表编制机器人作业程序,进行马鞍形焊缝工件试焊.所得的马鞍形焊缝成形良好,与人工神经网络的仿真结果相吻合.     

利用脉冲技术改善焊条电弧焊单面焊双面成形质量

针对焊条电弧焊实现单面焊双面成形存在的问题,研究了一种新型的采用脉冲电流的焊条电弧焊工艺——脉冲焊条电弧焊。以Q345E钢板为试验材料,研究了脉冲焊条电弧焊工艺对单面焊双面成形的影响。试验结果表明,脉冲电弧力可对焊接熔池形成有效的振荡和冲击,减少焊接缺陷,很容易实现对接焊缝单面焊双面成形。该研究为脉冲焊条电弧焊开拓了广阔的应用前景,具有重要的工程应用价值。     

向下立焊在大口径长输管道工程中的应用

向下立焊技术在长输管道施工中应用极为广泛,具有焊接速度快、生产率高、适合流水线作业、焊缝成形美观、内在质量好、无损检测合格率高的优点,尤其是单面焊背面成形平缓、均匀,与普通焊条电弧焊相比,具有明显的优势.介绍了管道向下立焊的焊接工艺及注意事项,并重点叙述了焊接过程中的焊接操作要领.     

焊接智能化与智能化焊接机器人技术研究进展

展示了上海交通大学机器人焊接智能化技术实验室近十年来关于电弧焊动态过程以及机器人焊接系统中的若干智能科学问题与智能化技术应用方向的研究工作进展,包括电弧焊过程的多信息传感技术,例如熔池信息的视觉特征,焊接电压、电流、声音及光谱特征提取;基于多信息融合算法的焊接熔透状态预测;焊接动态过程的智能化建模;焊接动态过程的智能控制方法;机器人焊接的智能化技术,例如机器人焊接过程中的焊缝导引及跟踪技术,焊接熔池和熔透状态的智能化控制;特殊环境下的自主焊接机器人系统的发展等.提出“智能化焊接制造技术——IWMT”及“智能化焊接制造工程——WIME”的概念,以期推动智能化科学技术在现代焊接制造业中的系统性研究与运用.期望展示的智能化焊接研究结果为现代焊接智能制造技术发展抛砖引玉.     

金属夹芯结构制造中的T型接头Stake焊接方法研究

T型接头的Stake焊接方法是实现金属夹芯板焊接制造的关键技术之一.为了论证焊接制造金属夹芯板的可行性,本文通过实验对比研究了在单一激光、TIG电弧和激光-TIG电弧复合等三种焊接工艺下,钛合金薄板T型接头Stake焊接焊缝成形特点及影响因素.结果表明,激光-TIG电弧焊是实现钛合金薄板T型接头Stake焊接的理想工艺,在焊缝组织、焊接效率、焊缝成形、间隙适应性等方面比单一激光或TIG焊接工艺有明显的优势,可以应用于金属夹芯板的焊接制造.     

TIG焊接过程计算机模拟的现状及发展

焊接电弧和熔池是焊接过程中的两大组成部分，笔者以TIG焊接过程为对象，讨论了TIG焊接电弧和熔池计算机模拟的现状，分析了模拟过程中存在的问题，并指出将焊接电弧和熔池动态结合起来进行分析和研究是未来焊接过程模拟的发展方向。     

The effect of tack welding on numerically calculated welding-induced distortion

A single-layer pulsed gas metal arc weld of structural steel S355J2+N with a thickness of 5 mm is experimentally and numerically investigated. Two tack welds are considered in the numerical simulation into two different ways. First, the tack welds are represented by elements belonging to the initial material. This implies that the “tack weld material” was not exposed to any thermal load or phase transformation before actual welding was performed. The weld seam is shortened and there is an influence on the stiffness of the whole structure affecting the calculation result. Secondly, the tack welds were simulated as conducted in the experimental welding procedure. The cases considering tack welding are compared to a simulation neglecting tack welding and to the experimental results.The influence of tack welds on the calculated welding-induced distortion is clarified and a contribution to an improved simulation-based prediction of welding-induced distortion is possible by modeling tack welding according to the realistic fabrication procedure.     

Microstructures and properties of laser/arc hybrid welds and autogenous laser welds in pipeline steels

Abstract

Lasers are capable of producing welds with deep penetration, low distortion and faster travel speeds, compared to arc welding. More recently, laser/arc hybrid welding processes have also been generating interest for industrial fabrication. In this paper, six carbon–manganese, mainly pipeline, steels were welded using both autogenous Nd:YAG laser welding, and Nd:YAG laser/MAG hybrid welding. The improvements in weld microstructures and weld metal toughness that are possible when using the hybrid process are described and illustrated. Laser/arc hybrid welding is shown to be a process that can generate good quality welds in commercially available pipeline steels. It also has the potential to complete girth welds in these steels with significantly fewer welding passes than are currently required for arc welded pipelines, reducing the joint completion time.     

Hybrid laser/arc welding process for controlling bead profile

Abstract

A laser hybrid welding process in which a defocused laser beam is applied beside a gas metal arc weld (GMAW) pool to modify the bead shape was studied. The present paper aims to produce welds with improved toe geometry and better fatigue life than those made with GMAW alone and to apply a numerical simulation to help configure the hybrid process. First, stationary hybrid welds were made to validate weld bead shape predictions and to characterise the spreading of the arc weld deposit to the laser heated spot. Next, the travelling hybrid process was configured with the aid of simulations and fatigue test specimens were welded. Proper application of the laser heat input induced molten metal to spread to the laser heated area, increasing the fillet weld leg length. This produced a larger weld toe angle that decreased the stress concentration and increased the fatigue life of the welds relative to standard mean values.     

气电横焊工艺技术改进

为了解决船舶横位置对接焊缝中存在的焊接效率低、质量可靠性差等问题,开展了针对船舶对接焊缝的气电横焊技术研究。通过对水冷铜滑块、陶瓷衬垫等关键条件的设计优化,将气电焊技术扩展至船舶建造横位置对接焊缝的焊接。随后对坡口形式、焊枪位置、摆动幅度等关键焊接工艺参数进行了合理的设计,结合船舶结构特点及工艺覆盖的要求,进行了3组不同板厚的横位置对接焊试验,测量了不同板厚的抗拉强度、硬度及冲击吸收能量,以验证工艺的可行性。结果表明,由于焊缝表面采用水冷铜滑块强制成形及焊缝根部采用陶瓷衬垫成形的影响,得到的焊缝成形美观,避免了焊后打磨处理,大大减轻了劳动强度;各个板厚的抗拉强度、硬度及冲击吸收能量等试验数据均满足船级社规范要求,并具有较大的工艺裕量;热输入最高可达93 kJ/cm,焊接效率相较于常规FCAW横焊提高了8倍左右。 创新点： (1)对陶瓷衬垫以及水冷铜滑块设计优化,有效解决了船舶横位置对接焊缝中根部焊缝的熔合问题。(2)将气电横焊技术用于船舶横位置对接焊缝的焊接,提高了横位置对接焊缝的焊接效率。     

铝合金超快变换复合脉冲方波VPTIG焊接技术

研究开发了一种适用于铝合金材料的新型超快速变换复合脉冲方波电流变极性电弧焊接方法,采用变极性TIG平板对接焊接工艺,分别对5A06,2A14和2219三种铝合金材料进行焊接,通过X射线探伤检测、接头拉伸性能测试以及断口扫描电镜等手段对铝合金的焊接质量和接头性能进行测试分析.结果表明,采用过零无死区时间且具有超快速电流上升沿和下降沿变化速率的复合超音频脉冲方波变极性TIG焊接工艺进行铝合金焊接,有利于改善和提高接头性能,获得满意的焊接质量.     

Weld pool shape prediction in plasma augmented laser welded steel

Abstract

A welding process that combined plasma arc welding with laser welding was used to make autogenous bead on plate welds on a sheet stock of a carbon steel. A wide range of welding parameters (arc current, laser power, weld speed) was employed. The experimental weld pool shapes were analysed and the data were used to train a neural network to predict weld pool shape as a function of process conditions. The predictions of the neural network model showed excellent agreement with the experimental results, indicating that a neural network model is a viable means for predicting weld pool shape. Using the model, a parametric study was carried out to examine the influence of process conditions on the final weld pool profile.     

A comparative evaluation of ultrasonic testing of AISI 316L welds made by shielded metal arc welding and gas tungsten arc welding processes

Ultrasonic testing of austenitic welds prepared by two different welding processes is studied in this paper. The two welding processes considered are shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) and the ultrasonic testing technique used is time-of-flight diffraction (ToFD). Identical artificial flaws were implanted in both welds during the welding process. Austenitic characteristics consisting of grain orientation distribution and anisotropy show that the GTAW specimen is more isotropic than the SMAW due to the orientation of its grains. Moreover, comparison of echo amplitudes shows higher attenuation for the weld prepared by the GTAW process. The specimens were examined by the ultrasonic ToFD technique under identical conditions. B-scan images obtained from ToFD measurements of the two welds indicate that inspection of the specimen prepared by the SMAW process is easier than the one made by the GTAW process due to higher scattering of waves in the latter. The measurements also showed that the probe positioning is very important in the detection of diffracted echoes when using the ToFD technique.     

Inverse Thermal Analysis of Heat-Affected Zone in Al2129 and Al2198 Laser Welds

Case study analyses of A12139 and Al2198 laser welds are presented. These analyses demonstrate the concept of constructing parameter spaces for prediction of properties within the heat-affected zone (HAZ) of welds using inverse modeling, which are in turn for process control. The construction of these parameter spaces consists of two procedures. One procedure entails calculation of a parameterized set of temperature histories by inverse analysis of the heat deposition occurring during welding. The other procedure entails correlating these temperature histories with a specific physical property of the weld that is measurable. The analyses presented here examines some characteristics of inverse modeling with respect to the prediction of hardness within the HAZ for deep penetration laser welding of the Aluminum alloys A12139 and Al2198. This study further demonstrates the feasibility of constructing a parameter space for the prediction of weld properties using weld cross section measurements that are independent of weld process conditions.