组合焊缝的焊接工艺评定

为便于准确地执行ＪＢ４７０８－９２《钢制压力容器焊接工艺评定》中关于组合焊缝的焊接工艺评定的有关规定,本文就不同种类的组合焊缝的评定方法分别进行了讨论,对于全焊 组合焊缝,专门举例说明了进行评定的具体试件制作方法。     

AWS焊接规范中 槽焊缝返修焊接技术研究

AWS D1.1《钢结构焊接规范》和AWS D1.6《不锈钢结构焊接规范》对槽焊缝的焊接工艺评定、焊工资质评定和焊接操作都进行了明确规定,但是在实际应用中仍然存在将槽焊缝的焊接操作和坡口焊缝或者角焊缝的焊接操作相互混淆的情况,槽焊缝缺陷导致的质量事件时有发生。针对槽焊缝返修焊接工艺制定及焊接操作技术等问题,总结分析工程现场钢结构及模块施工中实际案例,在常规焊缝返修工作的实践基础上,根据AWS焊接规范要求,对槽焊缝的返修工作提出了专业性的方法,包括缺陷去除、坡口制备和返修焊接工艺制定等,并详细介绍了不同焊接位置下槽焊缝返修的焊接操作技术。     

石化装置奥氏体不锈钢管道焊缝的热处理问题探讨

针对奥氏体不锈钢管道焊缝焊后热处理的问题进行探讨,通过焊接工艺评定和工程实践,证明了对奥氏体不锈钢管道焊缝进行焊后热处理的可行性,并提出了焊后热处理的注意事项。     

一种基于三维空间的焊缝跟踪精度评价分析方法

为了提高弧焊机器人的焊缝跟踪精度,提出了一种新的焊缝跟踪精度的评价方法,建立了基于三维空间焊缝的精度评价模型,该模型建立了焊接电流、焊接速度和焊枪高度等多个焊接工艺参数与焊缝跟踪精度之间的模型关系. 基于该模型,通过MATLAB对该模型进行仿真分析,验证了所提出精度分析方法和精度模型的正确性及有效性. 结果表明,在焊缝跟踪过程中焊接电流和焊接速度对焊缝跟踪精度影响明显. 该精度分析方法对于焊缝跟踪精度的评价具有一定的参照意义,并且在焊接工艺参数的合理选择时对焊缝跟踪精度具有重要影响.     

焊缝金属的强度匹配方式及其应用

本文介绍了焊缝金属强度匹配方式和类型,分析了焊缝金属强度匹配方式的工艺焊接性,列举了焊缝金属强度匹配应用实例。结果表明,焊缝的强度匹配方式有5种,拉伸试样断口部位各异。5种焊缝的强度匹配方式中,低强匹配和组合匹配方式的工艺焊接性得到改善,施工成本降低,接头的抗脆断性能能够控制;等韧性匹配的工艺焊接性取决于所用钢种和行业规定,施工条件较严格,成本较高,接头的抗脆断性能比较优良。14MnM oNbB钢低匹配专用焊条J506DP,可降低14MnMoNbB钢的临界预热温度50～70℃,改善了该钢的工艺焊接性;低匹配焊缝接头的强度已与母材等强,接头的安全性符合设计要求。组合匹配接头在综采支架立柱中应用表明,可使30MnNbXt钢在室温下焊接时不产生裂纹,而且在焊后状态下的使用性能完全符合产品技术条件要求。     

焊接焊缝变形的测量研究

针对目前无法采用先进的测量手段获取精确的焊接焊缝变形规律,使得焊接矫正工艺往往不能达到预期效果,提出一种非接触在线全场测量焊接焊缝变形的方法。基于数字图像相关技术,结合传统氩弧焊焊接工艺,对焊缝关键点进行全程跟踪测量并获取变形规律。此方法对焊接变形机制研究提供依据,提供焊接矫正方法思路,对焊接工艺具有重要的指导意义。     

厚壁焊接三通角焊缝射线照相工艺

采用4MeV直线加速器对厚壁(T≥50mm)焊接三通角焊缝的内部质量进行射线检验,如果照相工艺参数选择不当,不但严重影响焊缝缺陷的检出率,而且给底片评定和缺陷返修带来诸多不便,本文讨论了厚壁焊接三通角焊缝的射线照相工艺.1 焊接三通角焊缝的结构特点如图1所示,支管侧焊缝坡口,从腹部至肩部为0°～25°连续变化;而主管侧则依圆柱形态从与轴向正交断面变化到平行方向.焊接采取手工电弧焊,全焊透结构,在变位工装支持下挑立焊,外层以横焊盖面,属多层多道焊接.焊后镗掉内侧焊根或衬板.     

角焊缝低真空填丝电子束焊接

根据液力变矩器泵轮和上盖总成角环缝焊接的特点，通过试验论证提出了一种低真空填丝电子束焊接方法，解决了焊接质量与生产率的矛盾。本文详细讨论了束流形态、聚焦点位置、填充金属送进、电子束斑位置等主要填丝电子束焊接工艺参数对焊缝成形的影响。经试验与分析，提出了保证焊缝内在质量和良好外观形状的工艺措施。     

熔化焊锅炉接管角焊缝的射线透照技术探讨

指出在接管角焊缝圆周方向上穿透厚度的变化率和倾斜投影造成的影象畸变是确定透照工艺和进行缺陷评定的难点所在。提出目前可以采用并使之标准化的、规范化透照方法，以弥补国内锅炉、压力容器行业在管座角焊缝焊接质量监控手段上的某些空白。     

大直径厚壁圆柱管对接环焊缝的组合焊

针对大直径厚壁圆柱管对接环焊缝的焊接问题,提出背面焊条电弧焊打底、清根、正面埋弧焊填充的组合焊工艺。为此,我们正确选择焊接工艺参数,合理把握焊接作业节奏,调整热输入,控制温度特征,从而削弱了接头的淬硬倾向,防止冷裂纹的产生。实践证明,全熔透组合焊的对接环焊缝符合GB/T11345中一级质量标准。     

Controlling weld metal dilution for optimised weld performance in aluminium

Abstract

It is demonstrated how the current trend towards high speed, narrow groove welding, and the corresponding shift towards high base metal dilution, may result in decreased weldability for 6xxx and 7xxx aluminium alloys. In particular, variations in base metal dilution for extrusion alloys 6082 and 7108 have been examined for welds made with 5183, 5356, 5654, and 4043 filler alloys, particularly at high dilution ratios. The less common filler alloys 5039 and Safra 66 are also considered. Dilution curves superimposed upon existing hot cracking curves show that cracking susceptibility increases rapidly with base metal dilution for these alloys. Establishing an upper limit for dilution to avoid hot cracking, for a specific engineering application, also requires a knowledge of restraining conditions. For conditions of high restraint, i.e. rigid fixturing, enforcing an upper limit for base metal dilution will become critical. The effect of dilution on weld strength is also considered.     

活性剂对TA15钛合金对接及T形穿透焊接头的影响

穿透焊接头是钛合金薄壁结构的一种重要接头形式,文中从焊接参数、焊缝成形、焊缝气孔、焊缝金相、拉伸性能和气体含量等几个方面,阐述了活性焊剂技术对于TA15钛合金穿透焊接头的影响,同时与对接接头进行了比较.结果表明,活性焊剂技术对于穿透焊接头的焊接参数、焊缝成形、焊缝气孔和焊缝金相、气体含量等方面的影响规律与对接接头相类似,对于穿透焊接头静载强度的影响幅度与对接接头等同.     

基于焊点压痕的伺服焊枪点焊质量在线检测方法

针对目前车身点焊质量检测广泛采用的破坏性检验和无损检测方法中存在离线、小样本、检测成本高的缺点,借助于伺服焊枪编码器的位移反馈特性提出一种基于压痕的焊点质量在线检测方法.试验建立包括机器人及控制器、伺服焊枪和焊接控制器在内的点焊试验系统,利用伺服焊枪编码器位置反馈特性在线获取焊点压痕,通过PLC位移采集系统在线标定压痕获取精度,最后以0.8 mm的普通低碳钢板(GMW2)为例,完成基于压痕的焊点质量在线评价.试验结果证明,伺服焊枪编码器位置反馈精度能够满足焊点压痕测量要求,点焊接头质量在线评价的准确率符合实际生产要求,文中提出的基于压痕的点焊质量在线评价方法可以实现点焊接头的在线检测.     

Determining penetration from topside weld bead and weld pool geometry in PGMAW

Abstract

Finding suitable characteristic parameters of topside weld pool to reflect the penetration is a key work in weld shape control. In this paper, by analysing the molten metal volume, the relationship between topside weld bead shape and penetration in pulsed gas metal arc welding (PGMAW) is revealed, and then several weld bead characteristic parameters (WBCPs) are proposed to determine the penetration. However, these WBCPs are difficult to be obtained in real time, because continuous solidifying of weld pool forms the weld bead, and the WBCPs can be reflected by the weld pool geometry. Therefore, some weld pool characteristic parameters (WPCPs) are proposed to replace the WBCPs. Furthermore, a visual system is established and a series of image processing arithmetics are developed to extract the WPCPs.     

PWT-CWS.02NRT打底与RMS填盖焊接技术(二)

介绍了PWT外焊自动根焊和RWS自动焊填盖技术，重点讲述了自动焊技术中焊接材料的选用、焊接工艺参数的计算和焊接质量的控制。     

高强度焊缝金属韧化及钛—硼对组织的影响

随着焊缝强度的提高其韧性呈曲线变化,这与组织的变化有关,故提高韧性的途径有：减少先共析铁素体,增加针状铁素体;减少上贝氏体和M-A组元,增加下贝氏体;依靠夹杂物的形核核心作用;在铁素体组织中依靠钛硼复合韧化,在贝氏体组织中则只加钛不加硼,硼有抑制钛的形核核心作用;降低非形核夹杂物的含量;加入适量镍,韧化基体,它对各种强度级别的焊缝都有好的作用。     

Effect of weld microstructure on weld properties in A-TIG welding of titanium alloy

1　INTRODUCTIONTheactivatingTIGwelding (A TIG)wasfirstlydevelopedbyPatonWeldingInstitute ,Ukraine ,inthe 196 0s[1,2 ] .Itisnotuntiltheendof 1990sthatA TIGweldinghasbeenwidelyresearchedinEuropeandUS ,forexample ,TWIandEWI[3] .Thefluxes ,whichweredevelopedbyEWI ,havebeenappliedintheUSNavyshipbuildingindustry[4 ] .Theprincipleofthistechniqueisthatathincoatingofactivatingfluxiscoatedonthesurfaceofthebasemetalbeforeweld ing .ComparedwiththeconventionalTIGwelding ,the penetrationca…     

Effect of weld metal microstructures on cold crack susceptibility of FCAW weld metal

The effect of microstructures on weld metal cold cracking has been studied using flux-cored are welding (FCAW) wires with a 600 MPa strength level. Two FCAW wires were prepared by controlling the Ni content to allow a sufficient variation in weld microstructures, but with little change in the weld metal strength. The microstructural analysis showed that there was a significant difference in the proportions of the microstructural constituents of the weld microstructure. The 1.5%Ni wire resulted in a weld microstructure with a lower grain boundary ferrite (GF) content associated with an increased proportion of acicular ferrite (AF) than the 0% Ni wire. The GF contents of 0%Ni and 1.5%Ni weld metal were measured to be 19% and 6%, respectively. The cold crack susceptibility of these two FCAW wires was evaluated using the gapped bead-on-plate (G-BOP) test at the two different levels of diffusible hydrogen content As a result of the G-BOP tests, it was demonstrated that the 1.5%Ni wire had better resistance to cold cracking than the 0% Ni wire because its weld deposit had a lower GF phase content. This implies that, in addition to the hydrogen control approach, microstructural modification can be pursued to develop new welding consumables with an improved resistance to cold cracking. In the discussion, the detrimental effect of GF against cold cracking is addressed based on the microstructural characteristics of cold cracks in ferritic weld metal.     

PWT-CWS.02NRT打底与RMS填盖焊接技术(一)

介绍了PWT外焊自动根焊和RWS自动焊填盖技术，重点讲述了自动焊技术中焊接材料的选用、焊接工艺参数的计算和焊接质量的控制。     

Comparative study of weld residual stress on steel pipes with different weld types

This study developed a sequential coupling finite element procedure to predict residual stresses of steel pipes with longitudinal wela\ circumferential weld and spiral weld.The results show that the residual stress in heat affected zone(HAZ)is higher than that in weld for spiral weld pipe.For the circumferential weld pipe and spiral weld pipe,the residual stress in inner surface is higher than that in outer surface.However,for the spiral weld pipe,the residual stress in inner surface is smaller than that in outer surface.The hoop residual stress of circumferential weld pipe is higher than that of longitudinal weld pipe,while the axial residual stress of circumferential weld pipe is smaller than that of longitudinal weld pipe.The hoop stresses for circumferential weld pipe and axial stress for longitudinal weld pipe have exceeded the yield strength of base metal.With the increase of helix angle,the hoop stress decreases while the axial stress increases.For the spiral pipe(α=30° to 50°),both the hoop stress and axial stress are relatively small.The spiral pipe(helix angle ranging from 30° to 50°) is helpful to reduce stress corrosion cracking(SCC) and it is recommended to manufacture the steel pipe.