窄间隙P-GMAW多信息融合侧壁熔合状态识别研究

窄间隙焊缝坡口间距小且焊道较深,摆动中心与焊缝中心偏差较大时,坡口两侧侧壁受热不良,易发生未熔合缺陷。为了及时了解窄间隙侧壁熔合情况,掌握侧壁内部焊接质量,本文提出了一种基于BP神经网络和D-S证据理论的多信息融合方法,预测侧壁熔合状态。对窄间隙焊接未熔合缺陷产生机制进行了分析,研究发现焊接电弧信号和熔池变化与侧壁成形质量存在密切关系,为此进行了一系列偏差实验,建立了电弧电信号和电弧熔池图像信号的实时采集系统,采用批量特征提取算法,提取了与侧壁熔合状态密切关联的峰值电流、峰值电压、电弧弧长、熔池长宽比、熔池面积和熔池周长等特征参量。采用BP算法训练神经网络,在此基础上通过D-S证据理论进行决策级融合。实验结果表明,该模型识别率可达96.667%,避免了神经网络识别时的误诊,获得了比单一传感信息更好的预测结果,提高了熔合状态识别的准确度和可靠度。     

基于P-GMAW摆动电弧传感的窄间隙坡口宽度自适应焊接

针对窄间隙自动化焊接过程中,组对误差、焊接热变形等因素导致的坡口宽度不一致问题,本文提出采用电弧传感方式对坡口宽度进行检测,并根据检测结果调节工艺参数,保证焊接质量的方法。通过研究坡口宽度偏差的提取算法,分析窄坡口条件下脉冲熔化极焊接的峰值电流、基值电流和平均电流信号的传感特征,提出以脉冲周期内的电流均值作为特征信号,利用侧壁平均法进行偏差提取的传感方式;确定了坡口宽度变化时,焊枪摆幅、焊接速度的调控方法,实现了适应坡口宽度变化的自动化焊接。窄间隙焊接试验表明,上述方法能够有效识别坡口宽度变化,及时对摆幅、焊速进行调整,可在坡口宽度变化时,保证侧壁熔合质量和焊层厚度均匀。研究结果对单道多层窄间隙焊接实现焊接自动化,保证焊接质量具有一定的参考价值。     

厚板钛合金磁控窄间隙TIG焊接技术发展现状

磁控窄间隙TIG焊接技术能有效解决厚板钛合金侧壁熔合不良的问题,其工艺稳定性好、设备成本较低,能为大型钛合金海工结构和装备制造提供有力支撑。围绕厚板钛合金磁控窄间隙TIG焊接技术及其研究现状展开论述。重点阐述了外加横向磁场对电弧摆动的作用机理,并讨论了主要焊接工艺参数(窄间隙坡口设计、焊接电流强度、外加磁场强度和频率及电极位置)对焊缝成形的影响。结合自研结果探讨了不同规格钛合金磁控窄间隙TIG焊接接头的显微组织和力学性能,并进一步概述了焊后残余应力分布特征。研究结果表明,利用外加磁场实现电弧周期摆动能有效调控热输入分布,进而改善侧壁熔合不良的问题;相比其他窄间隙焊接技术,磁控窄间隙TIG焊接能获得更加均匀的焊缝组织和优异的接头力学性能;磁控窄间隙TIG焊接后,接头表面存在较大拉应力,结合合适的热处理工艺能有效降低接头残余应力。最后,对磁控窄间隙TIG焊技术发展和前景进行了展望。     

船用高强钢厚板窄间隙热丝TIG焊接工艺研究

采用12CrNi5MoV钢厚板在立焊位置进行窄间隙热丝TIG焊接工艺试验,研究了窄间隙坡口设计、坡口间隙、焊接电流、送丝速度、脉冲参数、钨极摆动等对焊道成形的影响。结果表明,窄间隙U形对称坡口使焊接填充量较传统X形坡口可减少76%;确定了厚板窄间隙热丝TIG焊接主要工艺参数,实现了150 mm厚12CrNi5MoV钢的高质量、高效焊接。     

窄间隙焊接

<正> 一、前言采用坡口边缘制备得基本上平行的窄间隙概念对厚截面材料进行电弧对接焊大约有二十年了,尽管研究文献的数量日益增多,但在欧州窄间隙焊实际应用的例子只有几个。虽然此焊接技术由于在节省焊接时间和降低焊接材料/能量的成本方面潜力大,而且有吸引力,但是它也有诸如倒壁熔合不良等这样一些长期存放的麻烦以及与去除缺陷和焊补有关的问题。加之经过验证可用的工业性焊接设备数量有限,这些无疑会使许多有可能采用此焊接技术的用户持保留态度。本文是根据由气体保护焊和埋弧焊技术小组为公开交换关于窄间隙焊之现状和发展前景     

新型窄间隙MAG旋转电弧传感焊缝偏差提取算法

针对旋转电弧窄间隙MAG焊多层单道焊时坡口变化平缓,传统电弧传感方法灵敏度下降的缺点,提出了1种新的电弧传感偏差提取算法.对通过实验获取的U形底对接坡口不同焊缝偏差下的电弧信号进行分析,得出偏差的大小和方向与1个旋转周期内电流极值的数目和分布有很好的对应性,并通过Matlab仿真进一步验证上述关系的合理性和可靠性.由此...     

CFETR真空室焊接接头力学性能分析

研究分析了中国聚变工程实验堆(CFETR)对真空室焊接的焊缝接头机械性能要求及本征特点,应用ANSYS软件建立了考虑热影响区的焊接接头有限元模型,数值分析了焊接接头结构参数与接头整体力学性能的关系,并基于窄间隙钨极氩弧焊制作了焊接试件,进行了性能测试和显微组织形貌实验。结果表明,试件未出现热裂纹和未熔合等缺陷;窄间隙钨极氩弧焊热输入较小,热影响区晶粒长大不明显,未出现明显软化,其宽度对提高焊接接头整体强度影响最大。阐释了焊接接头结构的力学特征及形成机制,为聚变堆真空室焊接接头结构设计和焊接工艺的优化提了供理论依据。     

焊接防变形综合控制技术在箱型钢构件制作中的应用

本文从复杂箱型钢结构的特点和焊接变形分析入手,详细阐述了在不能采用大型校正机械设备的情况下,如何合理运用焊接防变形综合控制技术,确保箱型钢结构焊接变形达到规范和设计要求的方法,对类似工程具有很好的借鉴意义.     

锁孔TIG焊接技术的研究进展

锁孔TIG焊接技术具有不开坡口、单面焊双面成形的特点,尤其适用于中厚板焊接。首先介绍了锁孔TIG焊的基本原理,然后分析了目前锁孔TIG焊接波形控制技术的研究现状,主要包括恒流锁孔TIG焊、单脉冲锁孔TIG焊和高低频双脉冲锁孔TIG焊。针对现有锁孔TIG焊接技术存在热输入量过大、接头组织晶粒粗大等缺点,重点介绍了一种新型的快频脉冲TIG焊接技术,它通过快频脉冲电流产生的电磁场对电弧进行压缩,控制焊接过程的热输入量,达到提高焊接质量的目的。与传统脉冲电弧相比,快频脉冲电弧的收缩效果更为明显,可细化焊接接头组织,将快频脉冲焊接技术应用于锁孔TIG焊是今后研究的热点和主要发展方向。     

超声相控阵检测在角接、T形焊接接头中的工艺试验

在制造阶段,由于管子与管座在应力作用下的变形与筒体孔边缘的变形不一致,必然引起附加的弯曲应力,同时其焊接接头的坡口几何形状呈多样性,坡口宽窄不一,焊接工艺复杂且焊接参数多变,焊接条件相对恶劣,容易产生未熔合、未焊透等缺陷,将会给产品、设备的安全运行带来严重隐患。     

船用高强钢焊接技术的研究现状与展望

船用高强钢焊接技术是当下造船行业中的重要技术之一,高效、优质的船舶焊接技术已成为船舶工业制造产业长期战略的关键因素。从船用高强钢传统焊接技术、高效电弧焊接技术、高效新型焊接技术等方面介绍了船用高强钢焊接技术的研究现状,重点讨论了船用高强钢焊接技术的细分领域现状,分析了船用高强钢焊接技术的发展趋势。研究表明,船用钢板的板厚朝着厚板、大厚板方向发展,船用钢板的强度朝着高强度、超高强度方向发展,国内外船用高强钢焊接技术相差不大,高效混合焊接技术、高新焊接技术是未来船用高强钢焊接技术的研究热点。     

Hybrid fiber laser – Arc welding of thick section high strength low alloy steel

Hybrid laser – metal active gas (MAG) arc welding is an emerging joining technology that is very promising for shipbuilding applications. This technique combines the synergistic qualities of the laser and MAG arc welding techniques, which permits a high energy density process with fit-up gap tolerance. As the heat input of hybrid laser – arc welding (HLAW) is greater than in laser welding, but much smaller than in MAG arc welding, a relatively narrow weld and restricted heat affected zone (HAZ) is obtained, which can minimize the residual stress and distortion. Furthermore, adding MAG arc can increase the penetration depth for a given laser power, which can translate to faster welding speeds or fewer number of passes necessary for one-sided welding of thick plates. In this work, a new hybrid fiber laser – arc welding system was successfully applied to fully penetrate 9.3 mm thick butt joints using a single-pass process through optimization of the groove shape, size and processing parameters.     

Microstructure characteristics of thick aluminum alloy plate joints welded by fiber laser

It's difficult to weld high strength thick plate since the groove is huge when using traditional arc welding, and the weld tends to be softened and large deformation could occur after multi-layer welding. All of these can affect the industrial application of high strength thick plate wielding. In this case, developing advanced welding technology and welding material is necessary to optimize the microstructure and performance of the welds. Fiber laser has many advantages such as good monochrome and high quality laser beam. In order to decrease the heat damage to the base metal from the welding heat source, low heat input is employed for welding thick plate. Fiber laser is applied in the welding of 20 mm thick Al–Zn–Mg–Cu alloy with super narrow gap filler wire. The microstructure comparison of Al–Mg–Mn alloy and Al–Mg–Mn–Zr–Er alloy welded joints reveals that a huge amount of fine equiaxed grains is formed in the weld zone of Zr and Er micro-alloying Al–Mg–Mn alloy welding wire and a great number of precipitation strengthening phases are precipitated in the weld zone after the heat treatment of welded joints in the entirety.     

Single Pass Laser-Arc Hybrid Welding of Maraging Steel Thick Sections

Maraging steel 250 grade plates of 10 mm thickness were welded in single pass using a laser-arc hybrid welding (LHW) setup comprising 3.5 kW CO₂ laser and synergic pulse metal inert gas (MIG) welding power source at a welding speed of 1 m/min. The influence of single-pass welding on the bead characteristics, microstructure, and mechanical properties was investigated. The size and volume fraction of reverted austenite was effectively reduced in the fusion zone. Moreover, the width of the heat-affected zones (HAZ) was reduced and the microhardness results did not show significant softening in the HAZ after post weld aging. Tensile testing of the welds in transverse direction showed 97.3% weld efficiency. The fusion zone exhibited K_Ic fracture toughness of 77.4 MPa√m which was affected by the distribution pattern of reverted austenite. The study vividly brings out the process advantages of LHW for accomplishing thick section welds of maraging steel in single pass with narrow groove and lesser filler wire consumption.     

316L/S32101异种金属焊接接头的显微组织与力学性能研究

目的 研究乏燃料水池用钢板316L与覆板S32101双相不锈钢的焊接性、接头不同区域显微组织特征及接头与母材之间的性能差异.方法 利用氩弧焊接技术对5 mm厚的316L底板与3 mm厚的S32101覆板以搭接的形式进行焊接,利用金相显微镜、扫描电镜、维氏显微硬度仪和电子万能材料试验机对焊接接头的宏观形貌、显微组织以及力学性能进行研究.结果 316L/S32101焊缝组织主要由铁素体基体、晶界树枝状奥氏体以及晶内细小片状奥氏体所组成;316L侧靠近焊缝处存在一个较窄的熔合区,其组织由奥氏体基体和少许细小分散的铁素体组成,而S32101侧靠近焊缝处组织则由粗大铁素体晶粒和沿晶粒边界分布的若干小块状奥氏体组成.从316L母材区到焊缝区,硬度显著增大,而从焊缝区到S32101母材区,硬度变化很小;焊接接头的抗拉强度高达510 MPa,为两侧316L和S32101母材强度的87.9％和88.6％.结论 在焊接电流为240 A和焊接速度为300 mm/min的条件下,可以通过氩弧焊获得成形良好的搭接接头,且接头的力学性能优异.     

Hybrid laser/arc welding of advanced high strength steel in different butt joint configurations

An experimental procedure was developed to join thick advanced high strength steel plates by using the hybrid laser/arc welding (HLAW) process, for different butt joint configurations. The geometry of the weld groove was optimized according to the requirements of ballistic test, where the length of the softened heat affected zone should be less than 15.9 mm from the weld centerline. The cross-section of the welds was examined by microhardness test. The microstructure of welds was investigated by scanning electron microscopy and an optical microscope for further analysis of the microstructure of fusion zone and heat affected zone. It was demonstrated that by changing the geometry of groove, and increasing the stand-off distance between the laser beam and the tip of wire in gas metal arc welding (GMAW) it is possible to reduce the width of the heat affected zone and softened area while the microhardness stays within the acceptable range. It was shown that double Y-groove shape can provide the optimum condition for the stability of arc and laser. The dimensional changes of the groove geometry provided substantial impact on the amount of heat input, causing the fluctuations in the hardness of the weld as a result of phase transformation and grain size. The on-line monitoring of HLAW of the advanced high strength steel indicated the arc and laser were stable during the welding process. It was shown that less plasma plume was formed in the case where the laser was leading the arc in the HLAW, causing higher stability of the molten pool in comparison to the case where the arc was leading.