紫铜与低碳钢的熔化极氩弧焊

通过紫铜与低碳钢的熔化极氩弧焊的生产实践，对铜钢焊接易产生裂纹、未熔合和气孔等缺陷进行了试验分析，并采用了合理的焊接工艺，提高了焊接接头的力学性能，保证了工件质量。     

AZ61镁合金钨极氩弧焊热裂分析

对AZ61镁合金进行了钨极氩弧焊走焊,然后在焊缝与母材的边界上进行钨极氩弧点焊,同时在点焊中心利用球形凸模加载使其变形。利用扫描电镜和能谱仪分析了试样裂缝分布规律、裂缝附近和晶界析出物的元素偏析情况。研究表明:与三次走焊试样相比,一次走焊试样的焊缝热影响区开裂较严重,具有沿晶式破坏特征,属于热裂缝;一次走焊试样裂缝附近出现了铝和锌元素的偏析现象,而三次走焊试样表面却出现了铝元素减少;点焊热影响区晶界析出物为低熔点共晶物γ-Mg17Al12。     

镍基690合金钨极氩弧焊堆焊层微裂纹分析

核电蒸汽发生器制造过程中常采用手工钨极氩弧焊方法堆焊镍基690合金,堆焊层表面的液体渗透(PT)探伤经常发现缺陷。通过模拟产品的堆焊工艺和表面加工状态的试验,分析缺陷的形貌和产生原因。堆焊层表面渗透探伤发现的缺陷主要是由于焊缝金属中微小的夹杂物引起的微裂纹。焊接电流大、焊接过程中保护不良、焊道间清洁度不够是引起堆焊层表面缺陷的主要原因,微裂纹的形成和数量的多少还与表面的加工方法有关。     

钨极脉冲氩弧焊封底技术

本文研究了TIG加填充丝单面焊背面自由成形的特点;低碳钢加填充丝TIG焊的冶金特点;工艺因素对焊缝成形的影响;焊接参数与电弧形态的关系;如何提高工艺适应性。最后给出焊接试验结果和结论。     

紫铜板熔化极氩弧焊的试验与生产

在各类大容量电炉的生产中,常有许多厚度不同的紫铜板需要焊接。我们曾采用埋弧自动焊的方法,顺利地完成了任务,但当需要焊接的紫铜板焊缝短而多时,埋弧自动焊就显示不出原有的优点。况且,     

钛合金的钨极氩弧焊

首先对钛合金做了简单介绍,特别强调钛合金在航空领域的应用,然后通过对钛合金焊接性能的分析,指出钛合金焊接时会产生脆化现象、冷裂纹和气孔问题。最后以8mm厚的TA7钛合金板为例,重点介绍在钨极氩弧焊焊接过程中应如何正确选择焊接工艺参数,应该采取哪些工艺措施保证钛合金的焊接接头质量。     

超声辅助钨极氩弧焊紫铜焊缝组织性能

针对钨极氩弧焊(GTAW)焊接紫铜厚板时热裂纹严重的问题,采用超声辅助GTAW新工艺研究紫铜板焊接工艺。通过动力学模拟得到超声辅助GTAW焊接时T3紫铜板振幅分布规律,确定焊接时超声入射的最佳位置,并发现超声功率越大,T3紫铜表面谐响应时对应的振幅越大。研究超声辅助钨极氩弧焊对T3紫铜焊缝显微组织和力学性能的影响。结果表明,经超声辅助后焊缝中热裂纹得到明显抑制,粗大柱状晶显著减少,焊缝中晶粒得到细化,等轴晶增加,有明显球化现象,出现明显亚晶界,在一定范围内,超声功率越大,细化效果越明显,亚晶尺寸半径越小。通过力学性能测试发现,焊接接头的硬度、屈服强度及延伸率与无超声作用时相比均有明显提升。     

紫铜厚板GTAW热裂纹形成原因分析

热裂纹是紫铜厚板气体保护焊接所面临的的主要问题,为了找出在紫铜焊接热裂纹中起主要作用的因素,研究了采用HS201焊丝进行紫铜厚板钨极氦气体保护焊接（GTAW）的热裂纹倾向问题,通过在空气中和充氩密闭环境中的刚性拘束裂纹试验的裂纹率,评定了热裂纹敏感性,指出了热裂纹的产生原因,结合填充材料、熔覆金属的高温延性,提出了热裂纹抑制方法.结果表明,热裂纹的形成原因是焊丝脱氧能力较差,导致氧侵入焊缝形成的Cu元素和铜的低熔共晶,在一次结晶的柱状晶晶界处偏聚,低熔共晶在应力下开裂.     

Double-sided gas tungsten arc welding process on TC4 titanium alloy

TC4 titanium alloy was welded by double-sided gas tungsten arc welding（GTAW） process in comparison with conventional GTAW process, the microstructure and mechanical performance of weld were also studied. The results indicate that double-sided GTAW is superior over regular single-sided GTAW on the aspects of increasing penetration, reducing welding deformation and improving welding efficiency. Good weld joint was obtained, which can reach 96.14% tensile strength and 70.85% elongation percentage of the base metal. The grains in heat-affected zone（HAZ） are thin and equiaxed and the degree of grain coarsening increases as one moves to the weld center line, and the interior of grains are α and α′ structures. The coarse columned and equiaxed grains, which interlace martensitic structures α′ and acicular α structures, are observed in weld zone. The fracture mode is ductile fracture.     

A novel molten wire tungsten inert gas welding process

ABSTRACT

A novel molten wire tungsten inert gas welding process was presented. In this process, a welding arc is used to melt the workpiece, and a melting arc is used to melt the feeding wire. Metal transfer is separated from the melting of the wire and the workpiece, and the arcs are stable no matter the droplet transfer mode is spraying or globular. The spatter rate in the process is close to zero. Mechanical properties of low carbon steel joint bonded with this process are superior to those bonded with the metal inert gas welding process.     

以空气为舱内加压气体的钨极氩弧焊接

研究了1～700 kPa空气作用下的钨极氩弧焊接.气体爆炸试验表明,压缩空气虽然不爆炸但是显著助燃,高压焊接试验舱舱内设备需要采取抗燃措施.采用较大的氩气流量,可以实现高压空气之下良好的电弧和熔池保护.自动焊机用于舱内焊接时,解决了线缆密封、摄像系统适应性等特殊问题,此外,以弧长代替电压作为控制变量消除了焊接电缆影响.16Mn钢平板焊接试验证明,虽然不同空气压力、不同位置实现单面焊自由双面成形的工艺参数明显不同,但是,采用脉冲焊接均可以获得性能优良的焊接接头.     

高压钨极氩弧自动焊接

研究了以0．1-0．7MPa压缩空气为舱内加压气体的钨极氩弧自动焊接。在提高高压焊接试验舱舱内设备抗燃性能的同时,供应足够的保护气体,焊接过程稳定。设计了钨极氩弧自动焊接试验样机。采用接触引弧,以高压密封圆形连接器实现了舱内焊接机头线缆的统一穿舱,特别是以弧长代替电压作为控制变量消除了焊接电缆的影响。16Mn平板焊接实验证明,虽然不同空气压力、不同位置实现单面焊自由双面成形的工艺参数明显不同,但是采用脉冲焊接均可以获得性能优良的焊接接头。     

A dynamic welding heat source model in pulsed current gas tungsten arc welding

A time-dependent welding heat source model, which is defined as the dynamic model, was established according to the characteristic of PCGTAW. The parabolic model was proposed to describe the heat flux distribution at the background times. The recommended Gaussian model was used at the peak times due to the bell-shaped temperature contour. The dynamic welding heat source was composed of these two models with a function of time.     

焊接工艺参数对超窄间隙焊接热裂纹的影响

超窄间隙焊接中热裂纹是一种很容易出现的缺陷,采用焊剂带约束电弧超窄间隙焊接试验,通过改变焊接工艺参数和间隙宽度,研究其对热裂纹的影响.结果表明,焊缝成形系数与热输入和焊缝成形系数与间隙宽度的匹配关系是决定热裂纹的主要因素.在较小的焊缝成形系数和较大的热输入量下热裂纹倾向较大,并且随着间隙宽度的减小,焊缝中热裂纹倾向明显增加.当焊缝成形系数增大到临界值时焊缝中不产生热裂纹,且临界值随热输入量的增大而逐渐增大,随间隙宽度的增大而逐渐减小.     

CO2激光-MAG电弧复合焊接保护气体的影响规律

保护气体是决定CO2激光-MAG(metal active gas)电弧复合焊接工艺稳定性、焊接熔深和接头质量的关键因素,但是相关的试验研究报道有限.对此,采用He-Ar和CO2-Ar混合气体在Q235钢板上进行了CO2激光-MAG电弧复合焊接工艺研究.结果表明,保护气体种类与配比对工艺和焊缝特征有明显的影响.He-Ar焊缝能够得到更大的焊接熔深和焊缝硬度.CO2-Ar中的CO2在高温下分解形成氧进入熔池后改变了表面张力系数,进而改变了熔池流动方向,导致在CO2≥30%后形成平整的焊缝余高,焊缝电弧区和激光区的过渡更加平滑.当CO2含量＞30%后,复合焊接工艺稳定性变差,焊缝硬度急剧降低.     

片状偏钨极电弧特性的数值模拟

基于流体力学和麦克斯韦方程组,建立片状偏钨极电弧三维数学模型,计算得到电弧温度场、流场、电场及电流密度分布.结果表明,片状偏钨极厚度方向电弧温度场、流场、电场及电流密度呈对称分布;相同焊接工艺参数下,片状偏钨极电弧最高温度、最大流速及电流密度小于圆柱钨极电弧;电流密度受片状偏钨极前端斜边引导作用和电弧惯性后拖效应的共同影响,其分布范围沿钨极宽度方向扩展,且电弧等温线在该方向上扩张;片状偏钨极前端斜边倾角的改变,会引起电流密度在钨极前端局部集中,并导致阴极下方高温区和阴极射流沿斜边偏移.     

Fabrication of multiple carbide particles reinforced Fe-based surface hardfacing layer produced by gas tungsten arc welding process

In this paper, a multiple carbide particle reinforced Fe-based surface coating has been in situ synthesized by gas tungsten arc welding (GTAW) melting a precursor mixture of graphite, ferrotitanium (Fe-Ti) and ferrovanadium (Fe-V) alloy powders on AISI 1020 steel substrate. The microstructure and wear properties of the Fe-based surface hardfacing layers were investigated by means of a scanning electron microanalysis (SEM), X-ray diffractometer (XRD) and wear tester. The results showed that (Ti,V)C multiple carbide particle and TiC carbide particle can be synthesized via reaction of Fe-Ti, Fe-V and graphite during GTAW melting process. The selection area diffraction pattern (SADP) analysis indicated that (Ti,V)C crystallizes with the cubic structure, which indicates that (Ti,V)C carbides were multiple carbides with V dissolved in the TiC structure. The Fe-based surface hardfacing layer reinforced by multiple carbides gave an excellent wear resistance and appeared a mild wear with fine scratches.