国际焊接学会(IIW)第75届年会于2022年7月17～22日在日本东京召开.会议形式为线上线下融合,会议内容涵盖了焊接领域的技术交流、教育培训及认证、标准制定、焊接青年人才成长等多个方面.从年会概况、年会国际会议、年会专业委员会工作会议、年会工作机构会议、中国机械工程学会焊接分会(CWS)与IIW合作共赢5个方面进行综述,为国内学术、工业和教育界的同仁提供国际焊接领域最新发展动态.近年来的IIW年会期间,CWS持续派出了 20余位专家学者全面参与IIW的学术交流与管理工作,为中国焊接领域的国际化发展做出了重要的贡献.
蛇形管高压加热器换热管与集箱管障碍焊接接头质量必须要满足100％的射线检测和渗透检测.满足探伤需求合格率是蛇形管高压加热器质量的关键,因设计结构,换热参数优胜于传统的U形管与管板.蛇型管高压加热器因自身结构管排之间空间受限,存在障碍和施焊盲区,在保证质量的前提下施焊难度大,返修难度更大.因结构形式导致换热管与集箱管的装焊顺序单一固定,焊接周期长.如果出现返修,对整个高压加热器的制造周期有严重影响.针对这种情况,进行模拟焊接,制定焊接训练计划,阶段性培训提升技能,选用手工钨极氩弧焊特制小型焊枪进行对称焊,送丝方式为内送丝.探索合理的焊接方法并进行训练,保证一次合格率,为整备产品制造周期打下良好的基础.
激光-熔化极惰性气体(Melt inert gas,MIG)复合焊过程中容易出现根部驼峰缺陷,为了实现焊接过程根部驼峰缺陷的同步预测,研究根部驼峰缺陷预测的算法并对其预测结果进行分析.采用高速摄像机进行复合焊接过程的实时视觉传感采集,提取焊接过程的正面熔池和匙孔的时序特征信息,并对这些特征信号进行小波包分解(Wavelet packet decompo-sition,WPD)与重构.应用激光扫描仪获得背部焊缝余高,以此作为驼峰状态标记的依据.再通过长短期记忆(Long short-term memory,LSTM)神经网络对焊接过程中根部驼峰状态进行预测.结果表明,WPD-LSTM算法对根部驼峰预测的准确率达到97.85％.相比其它算法,基于焊接过程正面视觉传感时序特征信息的WPD-LSTM算法预测准确率更高,且预测结果具有较高的连续性,有利于实现对焊接过程根部驼峰缺陷的同步检测与控制.
采用单钨极惰性气体保护焊(Single tungsten inert gas welding,STIG焊)、双钨极惰性气体保护焊(Double tungsten in-ert gas welding,DTIG焊)、激光-SDTIG电弧(L-SDTIG)复合焊和激光-DTIG电弧(L-DTIG)复合焊4种方式对6 mm厚TA2钛合金进行对接焊试验,实现单面焊双面成形.结果表明,L-DTIG复合焊的电弧能量更为集中,焊接速度可达680 mm/min.L-DTIG复合焊的热输入为605.5 J/mm,仅是DTIG焊的35.5％和L-SDTIG复合焊的59.0％.L-DTIG复合焊接头的焊缝区晶粒细小,显微硬度可达229.5 HV.拉伸试样在母材处断裂,接头抗拉强度优于母材.加入激光后,L-DTIG复合焊的电弧等离子体中心导电区在xOz和yOz平面电弧分别收缩51.0％,45.5％,电弧根部收缩75.0％.测得L-DTIG复合焊热源在工件上的电弧压力为3 465 Pa,分别是DTIG焊和L-SDTIG复合焊的4.17和2.25倍.较高的电弧收缩比和电弧压力可显著提高焊接效率,降低焊接热输入.
采用焊接热模拟技术制备了低合金高强钢双道次激光电弧复合焊热影响区的均匀化组织试样,研究了二次峰值温度对热模拟试样微观组织和韧性的影响.结果表明,未转变粗晶区为粗大的板条马氏体,晶粒尺寸在84～98 μm之间.超临界再热粗晶区为细小的板条马氏体,晶粒尺寸为15.7～19.2 μm.临界再热粗晶区为晶界和亚晶界分布有块状M-A组元的板条马氏体.亚临界再热粗晶区组织为板条马氏体,晶粒尺寸在79～88 μm之间.示波冲击试验结果表明,临界再热粗晶区试样抵抗裂纹形成能力最低,临界再热粗晶区和未转变粗晶区试样抵抗裂纹扩展能力最差.
针对一种屈服强度1 400 MPa新型超高强钢,对比分析了在使用低强匹配焊材的条件下MAG和激光-MAG复合焊的组织及性能差异.2种焊接工艺的成形及截面形貌均连续均匀,无气孔、裂纹、夹渣等微观缺陷.MAG采用2 mm钝边的60.坡口,热输入大、冷却速度较慢,焊缝组织主要为马氏体+贝氏体组织,焊缝-40℃冲击吸收能量为45 J,为母材的150％;热影响区冲击吸收能量为30 J,与母材水平相当;接头抗拉强度为1 166 MPa,相当于母材的69％.激光-MAG复合焊采用6 mm钝边的40.坡口,打底焊焊缝为马氏体组织;填充焊焊缝为马氏体+贝氏体组织;焊缝-40℃冲击吸收能量与MAG相当,但热影响区的冲击吸收能量达到42 J,优于MAG和母材;接头抗拉强度接近1 300 MPa,高于MAG 125 MPa,相当于母材的76％.激光-MAG复合焊焊接效率优于MAG,达到MAG的3倍以上.
为解决压力容器焊接生产过程学习与培训的问题,设计了虚拟卧式压力容器焊接生产线,采用3D Max建模软件构建了焊接操作机、滚轮架等设备、工具的三维模型,采用Unity3D设计了操作界面,用C#语言开发了操作流程,实现了与虚拟模型的交互.所设计的虚拟生产线包括下料、筒节成形、纵缝焊接、环缝焊接等9个工位,可以进行下料、焊前准备、纵缝焊接、环缝焊接等多项工艺的虚拟操作.所设计的虚拟生产线可以实现压力容器焊接的互动式教学,为大专院校虚拟试验教学和企业新员工虚拟实操培训提供了新的方案.
Test was carried out for the occurred weld root fracture phenomenon of ?24 mm 06Cr17Ni12Mo2 bimetallic thermowells during purging, and chemical composition, microstructure, mechanical properties, fracture morphology, resonance simulation test and other aspects of root weld were analyzed. The results showed that the reason for fracture had little to do with welding. The main reason was that three thermowells were arranged in the same straight line during purging, and thermowells produced transverse resonance and longitudinal resonance during the constant change of purging flow rate, which induced torsional fatigue brittle fracture of thermowells. In the later stage, the resonance was controlled by increasing diameter of thermowells and strictly controlling purge flow rate, thus eliminating the fracture phenomenon.
In order to compare and analyze influence of welding surface state on quality of diffusion weld, influencing factors encountered in the actual production process of diffusion welding were studied, and main verification factors included flatness, whether the machined（CNC milling） surface being treated, surface cleanliness and redundancy. All test specimens had the same welding process except surface state. After welding, tensile specimen were taken from test pieces, and influence of welding surface state on weld quality was determined by testing tensile strength of welded joints and analyzing morphology of fracture. The results showed that flatness of parts before welding would affect weld quality, and flatness of parts before welding need to control. The surface was not allowed to treat after machining（CNC milling）, the original machined surface need to retain, and grinding would affect weld quality. If welding surface was not clean, cleaning agent was not allowed for local cleaning, and the overall rework cleaning was required. Dust, wool and other excess materials affected weld quality, pre-welding assembly was best to carry out in clean room, and assemblers should wear a hood, mask, plastic gloves, and so on.
In welding process of high-pressure hydrogen storage tank, low alloy steel Q345R vessel head and S31603 austenitic stainless steel nozzle were easy to crack due to different materials and large size. To solve this problem, welding process of dissimilar steels was studied and tested, which included analysis of causes of major cracks, research on welding process methods and parameters, and welding tests. The result showed that welding scheme of using shielded metal arc welding to weld transition layer of vessel head, and then using argon tungsten arc welding to backing weld and using shielded metal arc welding to filling weld could effectively prevent occurrence of cracks.
Based on six-axis industrial robot and multi-information sensing signal fusion technology, a robot flame cutting workstation for automatic maintenance system of railway freight car with high precision and high weight loaded three-dimensional gantry structure on the sky rail side was developed. A method for rapid partition identification of automatic maintenance operation was invented, which overcame problems of missing positioning datum, random deformation and unequal damaged location of discarded car bodies. It solved industrial problems in the field of freight car maintenance that cutting process of scrap car body relied on manual work for a long time and was difficult to use automatic equipment.
Narrow gap laser welding of titanium alloy, nickel base superalloy, high strength steel, stainless steel and aluminum alloy was introduced. In the process of narrow gap laser welding, welding parameters such as laser power, welding speed and wire feeding speed, would affect microstructure and mechanical properties of weld, and groove size would affect side wall fusion of weld. If the welding process was not properly controlled, the conventional narrow gap laser welding might still cause problems such as side wall incomplete fusion of weld wall and porosity. New methods such as laser-arc hybrid welding, laser hot wire welding, ultra-narrow gap laser welding, swing laser welding, vacuum laser welding and electromagnetic assisted laser welding emerged at the right moment, which solved welding defects in narrow gap laser welding, and further broadened application field of narrow gap laser welding. Simulating and analyzing flow behavior of molten pool, keyhole stability and temperature field before welding could not only reveal complex physical processes and connection mechanisms of laser welding, but also be used to optimize welding process and obtain effective material connections.
Additive friction stir deposition was a new solid phase additive manufacturing technology developed in recent years. This paper briefly described the limitations of the traditional high-energy beam additive manufacturing technology for forming high-performance metal structural parts and the technical advantages of additive friction stir deposition technology. The main types of additive friction stir deposition technologies developed at home and abroad were summarized, including coaxial feed, preset feed, cold spraying compound friction stir, and consumable friction stir tool additive manufacturing, among which the research on bar coaxial feed developed by MELD company was the most advanced. Furthermore, the applications of additive friction stir deposition technology were presented such as in manufacturing and feature addition of lightweight and large structural parts, preparation of gradient materials and coatings, defect repair and new composite materials. Finally, the development trend of additive friction stir deposition technology was prospected.
In TIG welding process of 5083 aluminum alloy pipeline and equipment at the project construction site, there were often welding defects such as pores, cracks, inclusions, and so on. The existence of welding defects or repeated repair of welds could not meet the production requirements, and might even cause major hidden dangers to the safe operation of chemical plants. Causes of TIG welding defects of 5083 aluminum alloy during construction were systematically analyzed in the paper. Corresponding prevention measures for different welding defects were put forward, which effectively reduced the occurrence of 5083 aluminum alloy welding defects, and improved the first-pass rate of 5083 aluminum alloy welding at the project site. It provided reference for the subsequent improvement of welding quality of 5083 aluminum alloy.
The temperature field of 2209 duplex stainless steel surfacing was simulated by finite element method, and the effects of interpass cooling time, welding current, voltage and welding speed on the temperature field were analyzed. The results show that when multi-layer and multi-pass surfacing is applied, enough cooling time between passes can reduce the peak temperature and high temperature residence time of each weld bead, reduce the temperature rise caused by subsequent weld bead welding, and help to maintain the phase balance of the surfacing layer; When the subsequent weld bead is overlayed, it will lead to a higher temperature rise near the side of the previous adjacent weld bead, which has no significant impact on the center of the previous adjacent weld bead and beyond; During multi-layer surfacing, when the next layer of weld bead is welded, it will cause higher temperature rise of the corresponding weld bead of the previous layer; The increase of welding heat input leads to the increase of the peak temperature of the weld bead, the expansion of the high temperature zone, and the increase of the temperature rise of the previous weld bead.
Based on the classification of single pass weld experiments data of wire arc additive manufacturing, this paper analyzes the needs of users and uses them. Based on the Django framework under python programming language, a database system of wire and arc additive manufacturing is developed with B/S architecture. The system is developed by the combination of database and algorithm prediction model. It mainly sets three modules: user authority management, basic experiments data management and weld geometry prediction. It has the function of storing and expanding printing experiment data and predicting weld geometry under unknown welding process parameters. Different printing process methods introduce different BP neural network structures. When in use, the database system automatically reads the existing algorithm model in the database or trains a new model according to the existing experimental data. After entering the experimental data, the model will be retrained automatically, so as to realize the parameter prediction automatically adapted with the expansion or correction of the experimental data in the database, it can predict the weld geometry and size under unknown process parameters. Finally, a set of validation tests are designed based on MIG process to test the effect of the prediction function of the database. The prediction error of melt width is 1.3% and the prediction error of reinforcement is 1.5%, which shows the feasibility of the prediction function of the database system.
To explore the optimal process window range for TIG arc additive manufacturing of SUS304 austenitic stainless steel, single-pass multilayer wall forming tests were designed and conducted on SUS304 stainless steel using different deposition process parameters. The experiments were conducted to study the effects on the average width and height of the walls by varying the arc travel speed, wire feeding speed and interlayer cooling time, and to investigate the microstructure and mechanical properties of the thin-walls parts. The test results show that when the heat input is kept constant, the arc travel speed and wire feeding speed should match to ensure the stability of the deposition process. when kept the heat input constant, the average width of the deposited layer decreases from 10.54 mm to 7.5 mm and the average height decreases from 6.75 mm to 4.16 mm with the increase of the arc travel speed; the average width and height of the deposited layer increase with the increase of the wire feeding speed, and its height increases about 1 mm; With the increase of interlayer cooling time and the increase of the interlayer cooling time, the average width of the deposited layer increased significantly, from 10.54 mm at 2 min to 11.6 mm at 5 min, and the height did not change, which was around 6.5 mm. The microstructure of the deposited wall shows clear directionality, mainly composed of a large amount of austenite and a small amount of ferrite. Compared to the SUS304, the tensile strength in bothx and z direction is reduced to about 82.5% of that of the substrate, and the elongation in the x direction is greater than that in the z direction.
SA204B is a molybdenum alloy heat-resistant steel used for pressure vessels. The tensile strength of the material is 485～620 MPa, and the yield strength is not less than 275 MPa. At present, engineers and technicians have only conducted relevant experiments and researches on SMAW and FCAW processes of materials. In order to promote the welding automation of materials as soon as possible, relevant experimental researches and analyses have been carried out on GMAW processes of solid cored welding wires. During FCAW welding, because the drug core contains arc stabilizing agent, deoxidizing agent and slag-forming agent, it has good welding technology. In the welding process, the drug coating needs to be cleaned layer by layer, and continuous automatic welding of multi-layer and multi-channel cannot be realized. Through the test of SA204B material GMAW welding process, the process can meet the automatic conditions of SA204B material welding. According to the structure of the parts, the welding method is selected scientifically and reasonably, and the welding process is formulated. Under the condition of meeting the quality requirements of welding joints, the operation rate of welding equipment can be improved to the maximum extent, the welding cost can be reduced to the maximum extent, and the application range of welding automation can be expanded to the maximum extent.
Plasma, plume, sound, radiated light, electricity and other signals will appear in the laser welding process. By studying these signals and correlating them with the stability of the welding process and welding defects, real-time quality monitoring of laser welding process can be achieved. Through the introduction of laser welding characteristics and the comparative analysis of monitoring methods, it was concluded that the multi-sensor fusion technology had the advantages of rich monitoring information and high accuracy in welding status and defect prediction. According to the types of sensors compounded by quality monitoring system of laser welding process, the multi-sensor fusion technology was divided into four categories, multi-vision sensor, multi-optical sensor, optical and vision sensor, and other composite technology. Different multi-sensor fusion technologies were reviewed, realizing the advantages of optical and vision sensor composite technology that were sensitive to changes in welding status, fast sampling speed, and rich collection of information. Meanwhile, several advanced multi-sensor fusion products which could be applied to laser beam welding were introduced. Finally, the disadvantages and the future development direction of multi-sensor fusion technology were clarified.
采用搅拌摩擦加工制备了以AlCoCrFeNi2.1高熵合金为增强相的6061铝合金复合材料(AlCoCrFeNi2.1/6061Al),重点研究了加工道次对复合材料组织均匀性、界面结合以及力学性能的影响.结果表明,随搅拌摩擦加工道次的增加,AlCoCrFeNi2.1/6061Al复合材料组织均匀性及力学性能均得到明显改善.复合材料中基体与增强相界面结合良好,界面处扩散层厚度随加工道次增加而增大.相较于不添加增强相的6道次搅拌摩擦加工铝合金,AlCoCrFeNi2.1增强相颗粒的引入可进一步细化晶粒并提高抗拉强度,且随着加工道次增加,复合材料抗拉强度及断后伸长率均显著升高.2,4道次下的断口存在明显的颗粒聚集区,而6道次下断口表面颗粒分布均匀且呈现大量韧窝,为典型的韧性断裂.该现象主要归因于载荷传递效应、弥散强化和细晶强化3大强化机制.
