填充金属对5083铝合金焊接性能的影响

采用手工MIG焊接方法,ER5087焊丝与ER5356焊丝分别对3mm5083铝合金板材进行焊接,对焊接接头的表面成形、显微组织及力学性能进行检测,研究结果表明:采用ER5087焊丝的力学性能优于ER5356焊丝;两种焊丝的焊接接头抗拉强度分别达到母材94%和84%.     

新型轧辊堆焊加热炉的设计与使用

1 轧辊堆焊技术及其加热工艺要求简介 1.1轧辊堆焊技术轧辊堆焊,实质上是根据自动埋弧焊接原理,在堆焊电弧的高温作用下,将合金焊丝均匀地熔化在轧辊基体上,用焊丝将轧辊被磨损部位一层层填起,经重新车削孔型后再次使用。     

金属材料电弧增材制造技术研究现状

电弧增材制造（WAAM）技术将电弧作为热源，具备熔敷效率高、设备简单、成本较低的特点，在制备大型零件时具有更大的优势。基于3种典型电弧热源的电弧增材制造方法包括熔化极电弧（GMA）增材制造、非熔化极电弧（GTA）增材制造与等离子弧（PA）增材制造。GMA增材制造技术拥有熔敷效率高、易于实现等特点，特别是基于冷金属过渡（CMT）的增材制造技术取得了重要进展，主要缺点在于熔滴过渡对熔池的显著冲击易影响成形精度和质量。GTA增材制造技术具有最为稳定的电弧燃烧过程，具有无飞溅、成形精度与质量高等显著优势，特别适合于铝合金、镍基合金、钛合金等材料的增材制造。PA增材制造与GMA增材制造与GTA增材制造相比，存在能量密度高、集束性好等优点。但是PA合理参数区间较窄、参数匹配复杂、热输入大等缺点也限制了其在该领域的应用。由于增材制造过程使得后堆积层存在反复加热与冷却，增材制造成形件组织存在上中下区域的差异以及熔敷方向及垂直于熔敷方向性能的各向异性。增材制造金属材料的热循环过程对于晶粒尺寸、熔覆层性能以及成形精度非常关键，分别可以通过改变成形件冷却条件、改变熔池凝固条件对组织性能进行改善。新型电弧热源...     

熔嘴电渣焊在莱钢高炉炉壳立缝焊接中的应用

针对高炉炉壳立缝需要在垂直位置焊接及钢板厚度大的特点。为保证焊接质量。采用了熔嘴电渣焊焊接工艺。利用电流通过液体熔渣所产生的电阻热,将送入渣池的焊丝与导丝管熔化。作为填充金属。通过水冷滑块强制焊缝成形。同时,适当增大金属熔池的形状系数、减小焊缝晶粒结晶时的交会角。以减少焊缝偏析、降低热裂纹敏感性。检测表明。焊缝外观质量良好,射线探伤合格率100％,焊缝力学性能满足要求,高炉已经顺利达产。     

埋弧堆焊机导电嘴的结构改进

柳钢机械制造公司有2台自动埋弧堆焊机，其焊接嘴中心是个导电嘴。焊丝通过导电嘴的送丝导电孔送出，焊接电流通过此小孔传导给焊丝，导电后的焊丝与工件产生电弧而形成熔池。导电嘴的作用：一是按一定角度输送焊丝，二是将电流传导给焊丝。根据工况要求，导电嘴必须具有耐热，耐磨，导电性能好的特点，为了达到以上的性能要求，     

活化剂及其活化焊丝的工艺特性

本文对CO_2气体保护焊活化焊丝用活化剂和活化焊丝工艺性进行了研究。结果表明,用最佳配方的活化剂制备的活化焊丝,在CO_2电弧焊时,焊接电弧稳定,焊丝金属呈典型的细小颗粒过渡。飞溅率ψ降至2％左右,并且活化焊丝具有优异的焊缝成形及优良的焊缝力学性能,尤其是冲击韧性可提高2～3倍。在金相显微镜及扫描电镜下观察,活化焊丝熔敷金属的显微组织中存在大量的针状铁素体。EDAX结果表明,活化焊丝熔敷金属组织内有富钛夹杂物。     

展平型气保焊丝焊接工艺性能研究

通过加入适量S元素,制成新型的展平型气保焊丝,对新型焊丝进行CO2气保焊工艺性能试验。结果表明:采用展平型气保焊丝,焊接过程电弧稳定,焊接飞溅较小,焊缝表面波纹细小,焊接工艺性能有所提高;采用P-GMAW型焊机,其焊接工艺性能优于采用GMAW焊机;薄板焊接时,展平型焊丝小电流焊接能获得较好的焊缝成形。     

不同送粉速度对TC4钛合金表面激光熔覆的影响

采用光纤激光对TC4钛合金表面进行熔覆改性,研究送粉速度对熔覆工艺过程和熔覆层性能的影响。采用高速摄像机拍摄了加热粉末在空间的分布形貌,采用光学显微镜观察了熔覆层横截面形貌,采用EDS分析了熔覆层的氮含量分布,并测量了熔覆层横截面的显微硬度。实验表明,送粉速度较小时,粉末吸收少量激光能量,熔池较大,熔覆层宽而浅;送粉速度较大时,粉末吸收大量激光能量,熔池较小,熔覆层窄而深。当送粉速度较大时,熔覆层的氮元素含量和显微硬度均分布基本均匀,无明显梯度;随送粉速度增加,熔覆层显微硬度会增加,并稳定在约9.3 GPa。     

焊接工艺对镍基焊缝气孔的影响

针对镍基合金钨极氩弧焊焊缝中气孔形成的影响因素,采用高速摄像机、光学显微镜获得了气孔在熔池及焊缝中的形态及分布特征照片,研究了油污、送丝速度、保护气体和焊接电流等参数对熔池气泡的影响。结果表明:采用钨极氩弧焊对镍基合金焊接时,熔池表面有少量的气泡逸出,证明了焊缝金属中气孔源的存在;显微组织观察发现,有未及时逸出的气泡残留其中,但是利用UT,RT探伤手段无法检测出该类缺陷的存在;送丝速度和焊丝油污对焊缝金属中气孔的形成有明显的影响;适当调整其他焊接工艺参数对气孔影响均不显著。     

耐腐蚀钢Q345 NS焊接用材的研发

基于煤气管道用耐腐蚀钢Q345NS焊接施工的需要,开发了与之配套的焊丝和焊剂。对熔覆金属的力学性能和耐蚀性进行了检验,并研究了不同热输入量对焊接接头强度的影响。结果表明,熔覆金属的抗拉强度和屈服强度高于母材,耐蚀性能与母材相当;热输入为30～35 k J/cm时,进行了充分的冶金结合,冷却速度得以保证,接头强度高于母材,试样于母材处断裂。通过制定合理的焊接工艺参数,焊管接头强度高于母材,弯曲性能良好,冲击功相对母材没有明显降低,完全满足煤气管道的使用要求。     

Investigation on effect of pulse correction on structure property in dissimilar welds of galvanized steel and aluminum alloy obtained by gas metal arc welding cold metal transfer

Gas metal arc welding cold metal transfer (GMAW-CMT) method with AlSi₃Mn filler wire was performed on welding of the 5754 aluminum alloy with thickness of 3 mm to the galvanized steel with thickness of 2 mm aluminum alloy to investigate the effect of pulse correction on structure and mechanical properties of welded samples. In accordance with results, GMAW-CMT provides good tensile performance. It was attributed to the various throat weld size and wetting actions because of the influence of pulse correction on structure of welded joints. It was inferred that on employing +5 pulse correction resulted in better and consistent tensile strength of 209 MPa. Furthermore, the results showed that increasing the pulse correction led to increasing of flow in the filler wire and in fact raising of brazed seam width and throat weld size. In addition, the thickness of intermetallic compound layer which was formed along the interface during the GMAW-CMT was varied by changing of pulse correction. It has been found that by increasing the pulse correction from–5 to +5, the throat weld size increased and consequently led to a change in the tensile strength of the welded joints.     

ER70S-G焊丝焊接工艺性能的研究

为提高气保焊丝的焊接工艺性能,选用不同化学成分的ER70S-G焊丝进行焊接工艺试验。当焊丝含某种元素X质量分数为0.09%、w（Mn）为1.50%及w（Si）为1.0%时,CO2气体保护焊接飞溅极少,但焊缝宽高比较小,为3.5;当焊丝含某种元素X质量分数为0.01%、w（Mn）为1.70%及w（Si）为0.8%时,CO2气体保护焊接飞溅较少,焊缝宽高比较大,为4.5,显示出很好的焊接工艺性能。结果表明,焊丝的成分对气保焊缝的成形有很大的影响,在某种元素X质量分数、w（Ti）及w（Si）/w（Mn）比适当时,可得到焊接飞溅小、焊缝成形佳的焊接工艺性能。     

气保焊接用钢WER80S—G盘条的研制

采用先进的延迟冷却工艺在高速线材生产线上开发出550MPa级低硫、高韧性气保焊接用WER80S-G盘条,盘条ω（S）不高于0．005％。焊丝富Ar熔敷金属冲击功-30℃KV2平均达到170J以上,远高于设计要求。对比分析2种不同微量元素总量的盘条（焊丝）熔敷金属韧性以及2种不同保温罩状态设置轧制工艺时盘条金相组织的差异,据此优化WER80S-G盘条（焊丝）化学成分及轧制工艺条件,盘条具有F＋B组织,避免了淬硬组织,拉拔性能优良。     

粉芯丝材电弧喷涂的不稳定性分析

双丝电弧喷涂时,丝材顶端根据被加热状态可分为三个不同区域。其中,丝材顶端最外层被电弧直接加热（Ⅰ区）,这个区域的丝材完全熔化。由于传热效应使得相邻区域（丝材根部方向）的温度升高,从而产生软化区（Ⅱ区）。而与软化区相邻处（丝材根部方向）,传递的热量又软化了丝材并产生持续的变形区（Ⅲ区）,变形是由雾化气体所施加的动力产生的。采用高速摄像系统观察不同运行条件下丝材熔化、金属破碎并粒子形成的过程：Ⅰ区液态金属直接雾化成为很小的液滴,其尺寸是由熔化金属的特性和所施加的雾化气体压力所决定的,软化区是在阴阳极部位的金属薄片的源头。粉芯丝材的金属薄片要比实心丝材的尺寸小。受挤压作用形成的金属薄片形成二次引弧效应,因此增加了电弧喷涂过程的稳定性。本文分析了喷涂参数的影响、填充粉芯对熔化行为的影响、粒子形成以及喷涂过程的不稳定性,并将粉芯丝材和实心丝材的喷涂进行了对比。研究结果有利于提高双丝电弧喷涂模型的精度,并且可以通过优化喷管几何形状来增强金属液滴的雾化效果。     

TANDEM and GMAW Twin Wire Welding of Q690 Steel Used in Hydraulic Support

 Compared with using semi-automatic gas shielded arc welding, using automatic TANDEM twin wire welding and twin wire gas metal arc welding (GMAW) to weld Q690 steel, a low-alloy high-strength structural steel used in the hydraulic support in the fully-mechanized mining face, the welding speed, deposition rate, production environment and welding quality can be obviously improved. Compared with GMAW twin wire welding, a refined microstructure in the weld and heat-affected zone (HAZ), narrow HAZ and improved joint strength were achieved with TANDEM on Q690. Also, due to the push-pull pulsed way in TANDEM welding, the droplet transfer, distribution on heat flow and interaction between two arcs were completely different from those in GMAW twin wire system. The heat input of TANDEM is only about 766% of GMAW, and correspondingly, the welding speed and welding seam can be obviously improved. The complete oscillation caused by TANDEM pulsed current occurred in the welding pool, which refined the grains in the microstructure. The results show that TANDEM twin wire welding is very suitable in the welding of Q690 used in the hydraulic support.     

Mathematical modeling of three-dimensional heat and fluid flow in a moving gas metal arc weld pool

Mathematical models capable of accurate prediction of the weld bead and weld pool geometry in gas metal arc (GMA) welding processes would be valuable for rapid development of welding procedures and empirical equations for control algorithms in automated welding applications. This article introduces a three-dimensional (3-D) model for heat and fluid flow in a moving GMA weld pool. The model takes the mass, momentum, and heat transfer of filler metal droplets into consideration and quantitatively analyzes their effects on the weld bead shape and weld pool geometry. The algorithm for calculating the weld reinforcement and weld pool surface deformation has been proved to be effective. Difficulties associated with the irregular shape of the weld bead and weld pool surface have been successfully overcome by adopting a boundary-fitted nonorthogonal coordinate system. It is found that the size and profile of the weld pool are strongly influenced by the volume of molten wire, impact of droplets, and heat content of droplets. Good agreement is demonstrated between predicted weld dimensions and experimently measured ones for bead-on-plate GMA welds on mild steel plate.     

Effects of surface active elements on weld pool fluid flow and weld penetration in gas metal arc welding

This article presents a mathematical model simulating the effects of surface tension (Maragoni effect) on weld pool fluid flow and weld penetration in spot gas metal arc welding (GMAW). Filler droplets driven by gravity, electromagnetic force, and plasma arc drag force, carrying mass, thermal energy, and momentum, periodically impinge onto the weld pool. Complicated fluid flow in the weld pool is influenced by the droplet impinging momentum, electromagnetic force, and natural convection due to temperature and concentration gradients, and by surface tension, which is a function of both temperature and concentration of a surface active element (sulfur in the present study). Although the droplet impinging momentum creates a complex fluid flow near the weld pool surface, the momentum is damped out by an “up-and-down” fluid motion. A numerical study has shown that, depending upon the droplet’s sulfur content, which is different from that in the base metal, an inward or outward surface flow of the weld pool may be created, leading to deep or shallow weld penetration. In other words, it is primarily the Marangoni effect that contributes to weld penetration in spot GMAW.     

闪光对焊在宝钢冷连轧机组的应用

在酸洗机组和冷连轧机组上,闪光对焊作为一种有效的焊接方法得到了较为广泛的应用。宝钢1 220 mm轧机应用三菱公司NMW-C750F闪光焊机对轧钢坯料带钢前后端部采用闪光对焊工艺焊接。从来料、设备、工艺等方面详细分析了影响闪光对焊焊缝质量的因素,并根据冷连轧机组现场实际情况制定了一系列焊接工艺调整、备件周期维护等措施,有效地提高了轧钢中闪光对焊的焊接质量和可靠性,保证了1 220 mm轧机的正常运行。     

A unified numerical modeling of stationary tungsten-inert-gas welding process

In order to clarify the formative mechanism of weld penetration in an arc welding process, the development of a numerical model of the process is quite useful for understanding quantitative values of the balances of mass, energy, and force in the welding phenomena because there is still lack of experimentally understanding of the quantitative values of them because of the existence of complicated interactive phenomena between the arc plasma and the weld pool. The present article is focused on a stationary tungsten-inert-gas (TIG) welding process for simplification, but the whole region of TIG arc welding, namely, tungsten cathode, arc plasma, workpiece, and weld pool is treated in a unified numerical model, taking into account the close interaction between the arc plasma and the weld pool. Calculations in a steady state are made for stationary TIG welding in an argon atmosphere at a current of 150 A. The anode is assumed to be a stainless steel, SUS304, with its negative temperature coefficient of surface tension. The two-dimensional distributions of temperature and velocity in the whole region of TIG welding process are predicted. The weld-penetration geometry is also predicted. Furthermore, quantitative values of the energy balance for the various plasma and electrode regions are given. The predicted temperatures of the arc plasma and the tungsten-cathode surface are in good agreement with the experiments. There is also approximate agreement of the weld shape with experiment, although there is a difference between the calculated and experimental volumes of the weld. The calculated convective flow in the weld pool is mainly dominated by the drag force of the cathode jet and the Marangoni force as compared with the other two driving forces, namely, the buoyancy force and the electromagnetic force.     

Production of welding wire with ultrasonic removal of surface lubricant residues

An ultrasound device installed in the wire-drawing line permits the industrial production of welding wire with ultrasonic removal of lubricant residues from the surface, so as to improve wire performance. The welding wire produced in this way prevents disruption of electrical contact during welding and hence interruption of the arc, splashing of the metal, and other factors that impair weld-seam quality.