Static tensile strength characteristics of fillet welding lap joints assisted with bonding

A series of tensile tests were carried out on fillet welded lap joints assisted with bonding for investigating the static tensile strength characteristics of the joints from the viewpoints of stress reduction effect around the welded part due to bonding. It was confirmed that the mechanical properties of epoxy resin bonding used in this study were not deteriorated by heating to less than 150°C. When the fillet welded lap joints with bonding were assembled, the bond layer 20 mm from the weld toe was subjected to heating to over 150°C. In other words, the mechanical properties in that region deteriorated. The strengths of the elastic limits of specimens with welding and bonding were higher than those of specimens with only welding by from 60 to 100 MPa. The ultimate tensile strengths of them were almost the same because they were broken at the base plate. The strains around the weld toe and the root of specimens with welding and bonding were smaller than those of specimens with welding by around 13% in the elastic region. The strengths of specimens with only bonding were 170 MPa, which could be explained by a theory of elastic stress distribution. Even if the bond layer 20 mm from weld toe of the specimens with welding and bonding was thermally damaged, the possibility was confirmed that the residual bond layer had around 100 MPa in strength. It could be concluded that the strength of the residual bonding assisted to decrease the stress around the welded part of the specimens with welding and bonding.     

搅拌摩擦焊角接焊接外侧焊方法

在分析现有搅拌摩擦焊角接焊接的基础上,提出了一种新的搅拌摩擦焊(FSW)角接焊接外侧焊接方法(FSOCW).采用在角接头外侧镶拼辅助工艺垫块,在角接头外侧顶部构成搅拌头台肩摩擦所需平面的方法,将任意角度的角接焊转化为类似平板对接焊,利用垫板与搅拌头台肩产生的摩擦热加热角接焊缝,并在搅拌头搅棒的联合热机作用下形成搅拌摩擦角接焊缝.     

Research on laser-arc hybrid welding of lap fillet joints of thin sheet

ABSTRACT

Laser welding is capable of welding at high speeds by high-density energy, while arc welding is an effective construction method from the viewpoint of tolerance of the gap and welding position. Laser-arc hybrid welding has both these features. The authors have researched suitable welding parameters and consumables for this hybrid welding process that couples laser beam with MAG arc for lap fillet weld joining of thin steel sheets. As a result, the following welding parameters have been proven to be the most appropriate for better bead shapes and root-gap tolerance, i.e. laser leading (kept at a right angle) and MAG trailing (kept at a push angle); the laser-arc distance was 3 mm and the laser beam focus size was 2 mm. In addition, it was proven that HT490-class welding wire of Si-Mn-Ti type (JIS YGW11) was the most appropriate for better bead shapes and root-gap tolerance. The bead shape was apt to be better in cases of higher surface tension of welding wire. The result of the tensile shear test of the joint by welding with HT490-class welding wire of Si-Mn-Ti type (JIS YGW11) under selected welding condition demonstrated that the value of the tensile strength of parent material was equal to that of lab fillet joints.     

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,...     

2519铝合金角接结构的搅拌摩擦焊

利用自行研制的搅拌摩擦焊机采用一种搅拌摩擦焊外侧角接的新方法对厚度为22 mm的2519铝合金进行了角接焊接试验,并对焊缝的微观组织、硬度等进行了分析.分析了搅拌针断裂原因及得出其断裂方式为剪切断裂.结果表明,搅拌摩擦焊外侧角接焊接的方法能够有效地进行角接焊接;合理的焊接工艺和搅拌针形状是焊接的关键;旋转频率在30～4...     

双丝单电源单弧工艺在大焊角尺寸平角焊中的应用

介绍了在变压器油箱加强筋的焊接过程中,双丝单电源埋弧焊设备的选择和不同焊接参数下的施焊情况,包括双丝单电源埋弧焊机的结构配置内容以及设备的主要技术参数。从焊缝的外观、成形、咬边情况以及脱渣效果等不同方面对焊接参数进行优选。通过对比埋弧焊、气体保护焊在同等焊接强度时的焊接时间、焊角高度以及焊缝外观质量,体现出双丝单电源埋弧焊在焊接效率、焊接质量、焊缝外观以及焊材节约等方面的优势。同时也阐述了双丝单电源埋弧焊在使用方面的局限与不足。通过大量的焊接试验,确定了适合大型变压器油箱加强筋的埋弧自动焊工艺,提高了工作效率。     

激光钎焊及激光填丝熔焊在北京奔驰焊接中的应用

从设备应用及质量调整等方面介绍了激光钎焊及激光填丝熔焊在北京奔驰白车身上的应用。开发了一套完善的激光钎焊及填丝熔焊接系统,激光源选择TRUMPF公司开发的TruDisk系列激光源,激光工作头选用SCANSONIC公司开发的ALO3系列,并选配Weldeye系统对焊接过程进行监控记录;设计了一套基于ALO3激光工作头的工艺调试办法和参数设计,介绍焊接姿态、焊接参数以及焊接轨迹的设计;总结裸眼判断焊缝质量的方法,列举了单边连接不良、熔深以及气孔等几种常见的焊接缺陷以及优化方法。结果表明,激光钎焊及激光填丝熔焊焊接质量良好且长期稳定,废品率低。     

浅谈立角焊的质量控制

对立角焊中气孔，夹渣，未焊透，焊缝余高凸起，焊波脱节，咬边，焊脚尺寸过大等缺陷产生的原因进行了分析，并提出了有效的解决办法。     

Evaluation model for arc fluctuations of triple-electrode high speed fillet welding

To improve the welding efficiency of conventional arc welding, triple-electrode fillet welding was proposed and developed. Stability of triple-electrode fillet welding process is the assurance for ideal joint. The evaluation model for arc fluctuations of triple-electrode fillet welding was established based on the characteristic parameters and their variation coefficients. This model indicated that variation coefficients could reflect arc voltage flnctuations of welding process, and its analysis result was consistent with the actual welding process.     

Fatigue behaviour of out-of-plane gusset joints with one-side fillet weld

In previous studies, many fatigue tests have been performed to investigate the fatigue behaviour of out-of-plane gusset welded joints. However, fatigue behaviour of out-of-plane gusset joints with a one-side fillet weld has not yet been clarified sufficiently. In this research, in order to quantitatively clarify the behaviour, welding residual stress at the weld toes of the joint was measured by a cutting method. In addition to this, fatigue tests were carried out on the joints with a one-side weld and turn-around weld. The plate thickness is 9 mm and the weld size is 10 mm. Moreover, finite element stress analyses were conducted on the test specimen models and parametric models with different main plate and gusset plate thickness. Their results show that fatigue cracks for out-of-plane gusset joints with a one-side fillet weld initiate from both weld toes at the start and end points of weld beads and non-penetration weld of the gusset side. Also, the crack initiation points are different depending on the weld arrangement; however, their fatigue strengths are almost same.     

A5083P-O铝合金MIG焊接接头组织及疲劳性能研究

A5083铝合金为Al-Mg系防锈型铝合金,不可热处理强化,塑性较好,但强度较低,其耐蚀性和焊接性良好,退火状态时切削加工性较差。研究4 mm厚度A5083P-O MIG焊接接头的组织、硬度及其疲劳强度,发现接头的焊缝组织主要是以细小的枝晶为主,熔合线靠母材侧为垂直于熔合线的细长柱状晶粒。焊接接头各区域硬度值为70~80 HV,热影响区的软化现象不明显。接头的条件疲劳强度能够达到95 MPa。     

点焊后TRIP600钢板的疲劳性能

对最佳点焊工艺下强度为600 MPa的TRIP钢接头进行疲劳试验,获得了钢板点焊后接头的S-N曲线,结合硬度分布和疲劳断口形貌结果,分析了点焊后TRIP600钢板的疲劳寿命大幅降低的原因。结果表明,点焊后TRIP600钢板的疲劳极限为75 MPa,仅为母材的15.6%。焊后钢板疲劳裂纹源均产生在熔核周边未焊合的高温热影响区,高温淬火马氏体区与超级贝氏体最高温度回火最低硬度区的交界部位。该区强度最低,极易发生塑性变形,并引起应力集中。此处的淬火马氏体组织粗大,脆性较大,延塑性很低,且存在较大的残余拉应力,以及轴向拉应力和幅向应力的复合应力,使裂纹极易萌生并扩展。     

移动焊接机器人大折角角焊缝跟踪及工艺

针对移动焊接机器人大折角角焊缝自动跟踪焊接过程中,因折角处的焊接速度难以保持恒定,导致折角顶点处焊缝不均匀问题,提出了根据焊接速度实时在线调整焊接电流的方法.首先对大折角处机器人焊缝跟踪进行运动学分析,在折角处焊接速度以余弦规律变化,保证焊接的正常进行.同时根据焊接过程焊接速度的变化,在线调整焊接电流的思想,通过试验进...     

基于结构应力的焊接接头疲劳分析

基于结构应力法对来自相关文献中的16Mn钢十字非承载焊接接头、十字承载接头和纵向立板角焊缝接头的疲劳强度的试验数据进行了分析.推导了适合有限元计算的离散结构应力计算公式,得到焊接接头的结构应力集中系数.证实了该方法具有网格划分不敏感性,给出了应用结构应力法进行疲劳评定时适合上述各类接头的结构应力S-N曲线.结果表明,同名义应力法相比较,采用结构应力表示的焊接接头疲劳试验数据其分散性较小.     

国产厚板大功率激光填丝焊Y形焊缝的焊接工艺性

大功率激光的高功率密度特征使其成为船用大厚度材料高效焊接最有前景的方法之一.试验完成了10mm和12mm国产船用材料高功率CO2激光填丝焊的工艺设计,分析了焊接过程的光致等离子体行为.结果表明,当功率在13kW以上时随着焊缝熔深的增加斜率明显变缓;对于焊透的焊缝,仅仅用熔宽和熔深不能充分表征焊接参数对焊缝截面的影响;试验建立了激光填丝焊Y形焊缝形态模型,将Y形焊缝抽象成上半部分为梯形,下半部分为长方形的组合图形;在激光功率和焊接速度保持不变的条件下,研究了送丝速度和焊缝间隙变化时焊缝截面形态的变化规律.     

非承载角焊缝十字接头疲劳性能

文中基于结构应力方法对非承载角焊缝接头的疲劳性能进行了数值分析与试验研究。首先根据不同焊脚尺寸的十字接头焊趾截面结构应力,发现焊脚尺寸越大,接头疲劳性能反而越低,疲劳试验也证明了这一现象。同时,试验数据与BS 7608标准中F级S-N曲线的对比说明了疲劳评估时进行应力修正的必要性。然后,分别利用含装配间隙和熔深的有限元模型计算接头结构应力,证明两者对接头的疲劳性能影响很小。文中还通过与承载角焊缝接头的对比,证明细节特征对接头疲劳性能的影响程度与接头受力状态直接相关。在定义焊缝缺欠质量等级时,应考虑接头在结构中的受力状态,制定合理的控制参数,从而降低结构的制造成本。     

转向架耐候钢角接接头激光/激光-MAG复合焊工艺

为解决高速列车转向架耐候钢焊接构架中存在的焊缝根部未焊透问题,针对转向架焊接构架中典型的角接接头,采用激光/激光-MAG复合焊接技术进行系统的工艺试验,通过分析焊缝熔透及成形情况,确定适合激光/激光-MAG复合焊角接接头的坡口角度为35°、钝边尺寸为4 mm,以及相应焊接工艺参数。焊接接头无明显的淬硬组织,硬度测试结果满足相关标准规定。     

Influence of thickness of flange plate on the reduction of angular distortion by welding with trailing reverse-side flame line

In manufacturing of the steel bridge, fillet welded T-joint is widely used and angular distortion is often generated. So, reduction or control of angular distortion without additional processes to welding is strongly demanded because it takes great time and effort to correct the angular distortion. In this study, the effectiveness of welding with trailing reverse-side flame line heating for preventing angular distortion was investigated through the welding experiment and numerical simulation in submerged arc welding of fillet T-joint with three different thick flange plate. First, the heat source models for numerical analysis of both submerged arc welding and flame line heating were constructed based on the comparison with the measured temperature histories and angular distortion. And then, these heat source models were used in combination with various kinds of distance between two heat sources to make clear the appropriate distance condition for smallest angular distortion was 150 mm, and it does not depend on thickness of flange plate. It was also confirmed that the experimental angular distortions were in good agreement with those calculated. With a focus on the influence of thickness of flange plate, the reduction of angular distortion by welding with trailing reverse-side flame line heating becomes smaller with increasing thickness of flange plate. However, angular distortion could be adequately prevented under the appropriate flame line heating condition in either thickness of flange plate because the welding-induced angular distortion also becomes smaller with increasing thickness of flange plate. Thus, it was concluded that welding with trailing reverse-side flame line heating could be useful for preventing angular distortion of fillet T-joint, which is a component of steel bridge, enough not to correct it after welding.     

车体结构铝合金焊接接头疲劳性能研究

铝合金因其质量轻、力学性能好成为列车车体制造的首要选择.而焊接是铝合金车体制造的主要方式,但铝合金焊接接头的疲劳性能与钢相比较差,疲劳断裂是铝合金焊接结构的主要失效方式之一.采用疲劳试验与数值分析相结合的方式,研究铝合金焊接接头的疲劳性能.研究结果表明:铝合金焊接接头是在比较低的交变应力条件下发生断裂的.瞬断区上有明显的舌状花样,断裂方式为典型的解理断裂,在断口上有较低的脊岭.材料中产生的空穴往往是裂纹源萌生的源头.焊接缺陷气孔和未焊透造成试件在几何形状上的不连续和截面面积的减小,导致应力集中现象产生,降低试件疲劳性能.     

超声频分量双周疲劳载荷作用下焊接接头疲劳行为

使用带超声频载荷分量的双周疲劳试验装置对Q345钢焊接接头分别进行纯低周、纯高周以及双周循环加载条件下的疲劳试验.应力比R为O.5,高周载荷频率约19 kHz.结果表明,叠加于大幅低周循环载荷上的小幅高周循环载荷及叠加于大幅高周循环载荷上的小幅低周循环载荷都能够对焊接接头造成严重的疲劳损伤.通过按外包络线表征双周疲劳强度,如果疲劳寿命使用低周载荷循环周次表征,低估了高周载荷分量对焊接接头造成的损伤;如果疲劳寿命使用高周载荷循环周次表征,又高估了低周载荷分量对焊接接头造成的损伤.