球罐球壳板组对焊缝清根坡口的磁粉检测

对大型球罐压力容器的切片球壳扳进行安装时,一般都会使用现场焊接的方法。球壳板的厚度一般超过30mm,在焊接过程中,很容易影响整个安装工艺的质量,如焊接根部与内外表面发生未焊透、裂纹、夹渣等。要想避免以上缺陷的影响,就要对焊缝进反复进行磁粉检测,检测部位主要有焊接之前的球壳板坡口、焊接中焊缝坡口清根、焊接之后热处理之前焊缝及热影响部位、水压后焊缝及热处理部位等。在所有检测部位中,对清根坡口进行磁粉检测是重中之重。有关结果表示,球罐赤道带之上的焊缝很容易引起应力裂变夹渣、未融合等缺点。对清根坡口进行磁粉检测,可以更加准确的检测出根部袁面的缺点。     

焊缝组织细化下建筑钢结构焊接接头性能探究

钢结构焊接属于建筑工程中的重要施工技术，钢结构焊接质量能够直接影响整个建筑结构的应用价值。本研究结合特定工程案例，对焊缝组织细化下建筑钢结构焊接接头性能进行深入研究。最终得出，基于焊缝组织细化的焊接，焊缝的抗拉强度、断裂韧度等指标与母材相比均存在一定程度的提升，其综合质量基本能够满足建筑钢结构的受力性能要求。     

焊接实腹吊车梁疲劳断裂的探讨

焊接结构的断裂分析,实质上是结构物中焊缝及其附近基本金属的断裂分析。焊接接头处具有焊接热循环所造成的各种不利因素,从而产生缺陷,形成焊接结构的最薄弱环节。只要该处具有一定的抵抗裂纹扩展的能力,则整个结构物就很少有脆性破坏的可能。     

电梯安装工程构件焊接工艺

电梯安装工程中导轨压块、支架、承重梁等构件都采用焊接件。这些工件采用双面连续焊接．焊缝不长,但它们对整个安装工程却是举足轻重的。同时电梯安装构件的焊接一般都采用手工电弧焊,具有机动灵活的特点,但又有质量不稳定的缺点,掌握不当,很容易产生焊缝缺陷和焊接变形。为了保证电梯的安装质量和安全使用,必须制订合理的工艺规范,并在生产中严格执行,以到达预期的效果。     

敞车端墙反面焊缝机器人自动焊生产线的结构及应用

<正>0前言在端墙生产中焊接量占整个工序作业量的70%,因而,焊接生产的技术水平高低将影响端墙制造质量。南方汇通股份有限公司在充分调研和比较后,在原有端墙正面龙门焊接线的基础上,与哈尔滨焊接研究所联合共同研制了端墙反面焊缝机器人自动焊接生产线。     

十字对接焊缝在厦门BRT高架桥中的应用

针对厦门BRT高架桥钢箱梁制造中面板十字交叉对接焊缝进行结构分析和工艺试验,研究该桥十字交叉对接焊缝的焊接工艺对力学性能的影响,确定钢箱梁十字对接焊缝的焊接工艺方法和保证焊接质量的措施。焊接工艺试验中所选用的坡口形式、焊接材料、焊接参数、焊接方法及工艺措施是合理可行的。     

不同焊接工况焊接效应对箱板装配式钢结构加劲墙板的影响

通过ABAQUS关联DFLUX热源子程序对Q235B与Q345B钢板进行焊接模拟,并利用超声波检测方法对钢板进行焊接残余应力测试。试验发现：在焊缝热影响区上的纵向残余应力以拉应力为主,在整个焊件上横向残余应力既存在拉应力又存在压应力,且试验结果与模拟结果基本吻合,验证了ABAQUS模拟钢板焊接的可靠性。采用相同模拟方法对加劲钢板墙焊接过程进行模拟并对其焊接残余应力、焊接变形以及抗剪承载力进行分析。结果表明：加劲钢板墙的焊接残余应力与焊接变形主要发生在加劲肋与墙板焊缝处,沿焊缝方向上的残余应力均呈现上下两端小、中间大的特点;间断焊接对加劲钢板墙的高残余应力以及整体残余变形影响明显低于连续焊接;在所有焊接工况中,最小极限抗剪承载力与最大极限抗剪承载力相比下降了6.8%;对比所有工况后发现间断距离较大的焊接工况效果更好。     

天然气管道焊缝射线探伤技术

天然气管道安装中焊接是整个施工中最为重要的环节，焊缝质量的好坏关系到整个工程的安全与使用。无损检测是焊接检验的最终环节，主要方法有射线探伤(RT)、超声波探伤(UT)、磁力探伤(MT)、着色探伤(PT)等。文章主要就射线探伤工艺作简要阐述。     

焊接工艺参数对焊缝力学性能的影响

<正>0前言焊接工艺参数包括焊接热输入、道间温度、焊接位置及焊接材料直径等。焊接热输入集中反映了焊接电流、电弧电压和焊接速度的综合影响,它是决定焊缝冷却速度的主要环节之一;道间温度(通常在计算公式中采用预热温度)是决定焊缝冷却速度的另一个主要环节。焊接位置及焊接材料直径也会影响到冷却速度,还会影响到焊缝中各结晶区的组成比例。总之,影响焊缝力学性能的主要因素除了化学成分之外,就是冷却速度了。     

不锈钢在建筑工程中应用及其焊接性能研究

对建筑中使用的不锈钢进行了分析,并采用搅拌摩擦焊接和钨极氩弧焊分别对建筑结构中使用量最大的316L不锈钢进行了焊接,对焊缝的力学性能、腐蚀性能和外观平整性进行了分析。结果表明:搅拌摩擦焊接焊缝的抗拉强度可达493 MPa,是母材抗拉强度的83.6%,延伸率为母材的52.1%;钨极氩弧焊接焊缝的抗拉强度为475 MPa,是母材的80.5%,延伸率为母材的40.8%。搅拌摩擦焊接316L不锈钢后焊接焊缝的抗腐蚀性能良好,焊缝平整美观,可作为建筑结构及装饰用不锈钢材料焊接的优选技术。     

箱型柱焊接工艺

基于箱型柱焊接制作工程实例,依据相应规范、规程并通过长期钢结构制作过程的经验积累,简述在现有的国内通用焊接设施装备下箱型柱关键部位的施焊过程,对构件在车间及现场的焊接工艺进行经验总结,介绍箱型柱焊接工艺的重点。在箱型柱制造施工中,这些工艺的合理使用能更好地保证其焊接质量。     

轻钢结构焊接变形的火焰矫正施工方法

根据多年经验 ,结合国内外有关资料 ,阐述火焰矫正焊接变形的原理 ,轻钢结构焊接变形的主要种类 ,介绍焊接变形的火焰矫正施工方法     

大型高压天然气球罐现场焊接的质量控制

分析了就大型高压球罐的施工中影响焊接质量的，对如何改善、提高焊接质量提出看法，并对具体方法进行了阐述。     

钢管桁架结构大间隙焊缝相贯节点性能试验与理论研究

河南艺术中心艺术墙与屋面钢结构均采用钢管相贯桁架结构体系。复杂建筑几何造型、运输变形、焊接变形、安装误差等多方面因素,使钢管相贯节点处腹杆相贯线与弦杆间隙远超过规范要求。为解决大直径、相贯线大间隙焊缝的圆钢管相贯节点安全问题,选定2个节点制作足尺试件进行试验研究,相贯线处间隙取30mm并按拟定的焊接工艺施焊;建立节点三维实体有限元模型进行弹塑性有限元分析;通过对比分析,确认工程大直径钢管、大间隙相贯节点的安全性,同时验证了规范公式及有限元分析方法对该类节点设计的适用性,对钢管相贯节点承载力(破坏)判定准则进行了探讨。     

角焊缝连接设计中值得探讨的一个问题

通过对角焊缝连接设计的分析讨论 ,提出一个值得探讨的问题 ,并就角焊缝连接设计给出一些有益的建议。     

单面焊接H形截面短柱极限承载力研究

通过单面焊接H形截面短柱极限承载力试验和相应的有限元计算与分析 ,表明在静力荷载条件下 ,较薄腹板构件的极限承载力对单面角焊缝接头并不敏感 ;但在腹板较厚的构件中 ,角焊缝的相对熔深对其极限承载力有一定的影响。     

Special all-round fillet weld for anchor rods of base-plate T-stub connections

The eccentricity between connected steel parts and the anchor rods in base-plate T-stub connections makes base plates the weaker components in tension and compression. Additionally, the oversized holes in base plates lead to irregular placement of anchor rods, resulting in an unsymmetrical shear behavior. Thus, this paper aims to develop a special all-round fillet weld to connect the anchor rods beneath the base plate concentrically to the steel part, removing the base plate from the load-transferring chain. Accordingly, design criteria were first developed based on Eurocode's directional method considering all the potential failure modes. Next, results were validated by conducting experimental work. The digital image correlation technique (DIC) was also used to capture the strain distribution developed over the tested specimen till failure. Consequently, numerical analysis was carried out to investigate the fracture strength and the fracture angle and compare the special fillet weld with its equivalent standard one, which has the same weld volume. The results indicated that the proposed design criteria produced safe strength prediction for the developed special all-round fillet weld. Furthermore, the results revealed that using a special all-round fillet weld instead of the equivalent standard one can increase the strength by about 8% and improve the ductility of the weld. However, it decreases the stiffness of the weld by about 21%. The fracture surface occurred at $15°$ from the face of the anchor rod, which produced a higher strength than the predicted tensile strength calculated according to the theoretical throat plane.     

The strength of planar fillet weld groups subjected to an eccentric shearing force in their planes

The method developed previously for estimating the strength of fillet welded connections subjected to a shearing force only and of planar fillet weld groups subjected to an eccentric force applied outside their planes is used to analyse some planar fillet weld groups (Fig. 3) subjected to an eccentric shearing force in their planes. The welds are assumed to have equal leg lengths which are the same for all the welds belonging to a group. The line of action of the applied force is either parallel or perpendicular to the directions of the welds in a group. The strength is predicted as a function of the weld group geometry, the load eccentricity and the weld metal UTS. The effect of the longitudinal residual stress locked into the welds during the fabrication is allowed for. The theoretical predictions are compared with experimental results and it is concluded that the theory will provide lower bounds on the strengths of the connections investigated if the weld metal UTS obtained from tension tests on specimens cut from deposited weld metal is used in the calculations.     

大跨度空间管桁架设计与施工的若干问题

重点阐述了大跨度空间管桁架设计与施工存在的主弦管不等壁厚对接、K型节点不可见焊缝(搭接焊缝)、节点强度不足、相贯节点焊缝、桁架施工程序等五个方面的问题,并以此为出发点进行一定外延与扩充,提出对相关问题在设计与施工时的处理方法.     

A modified moment resisting connection for ductile steel frames (Numerical and experimental investigation)

The seismic behavior of steel moment resisting building systems are directly affected by the local behavior of beam to column connections. In welded connections, severe stress concentrations at the connection edge coupled with imperfections of the weld roots, may contribute to significant reduction of the seismic performance. In this study, a reduced plate section connection is proposed to shift the stress concentration from the connection face. With this aim, the authors propose drilled holes at cover plates to create an intentional weak point. Applying this method, the stress concentration at the weld roots is significantly diminished and the failure mechanism is altered from premature weld fracture to ductile plate yielding around the holes. This technique eliminates unfavorable local beam failures present in some similar methods and also forces the cover plate to behave as the replaceable fuse of the connection system. As it is revealed from the finite element and experimental investigations, the strength and ductility capacity of the considered connection type is significantly improved and the behavior of the connection seems to be far less dependant of the weld root quality. This might improve the structural reliability of the connection due to the guided failure mechanism.