活性剂涂敷量对A-TIG焊熔深影响的研究

常规TIG焊生产效率低，单道焊可焊厚度小，活性化TIG焊（A-TIG），同常规TIG焊相比可大幅度地提高焊缝熔深，从而提高焊接效率，针对不锈钢材料，通过宏观断面分析方法研究了单一成分的活性剂（SiO2,CaF2,TiO2,Cr2O3和NaF)对焊缝熔深的影响，结果表明：同常规TIG焊相比，上述5种活性剂在涂敷量较小时，焊缝熔深均随活性剂涂敷量的增加而明显增大，氧化物活性剂增加熔深的作用效果大，氟化物的作用效果较小；5种活性剂在熔深增加能力上均有一个饱和点；电弧收缩和熔池表面张力梯度的变化是活性剂增加熔深的主要原因。     

蒙乃尔合金活性化TIG焊工艺

介绍了采用活性化焊剂TIG焊(A-TIG)对蒙乃尔合金400进行焊接的工艺评定情况。在A-TIG焊条件下,该工艺可以单面完成6mm及双面完成10mm直边对接板的焊接;对焊接头进行的金相组织和力学性能试验表明,使用A-TIG焊不仅能够大幅度增加焊接熔深,还能获得优良的力学性能;同时可节省昂贵的焊材。A-TIG焊焊接蒙乃尔合金是一种值得推广的焊接新工艺。     

A-TIG焊接方法研究现状及展望

TIG焊作为一种高质量焊接方法的代表,具有焊接过程稳定、焊缝成形美观、焊缝质量高、焊接过程无飞溅等优点,但同时也存在单道焊接熔深浅、焊接速度慢、熔敷速率低等缺点.为了克服TIG焊存在的缺点,提出了A?TIG焊接方法,该焊接方法是先在待焊焊道表面涂覆一层活性剂,然后再进行施焊.该焊接方法在保留TIG焊优点的前提下,可以显著增大TIG焊单道焊接熔深,提高焊接生产效率.近几年很多学者对A?TIG进行了大量研究,也开展了A?TIG焊在工业生产上的部分应用,但是A?TIG焊仍存在以下几方面问题:(1)A?TIG焊接需要涂覆活性剂的工序,不利于实现焊接过程的自动化,且活性剂的涂覆很难保证均匀稳定,限制了其在工业生产上的应用.(2)活性剂增大焊缝熔深的机理尚未形成统一的认识,对该机理的研究还不够深入.(3)需要针对不同的焊接母材开发不同的活性剂,且不同学者开发的活性剂千差万别,缺少统一的衡量标准,不利于活性剂的产业化.针对不锈钢、铝合金、钛合金、镁合金、低碳钢等各焊接母材开发了增大熔深效果比较明显的活性焊剂,并且研究了活性焊剂对焊缝的表面成形和组织性能的影响.在活性剂的引入方面提出了气体输送活性剂的方式,基本实现了焊接过程的自动化和活性剂的均匀涂覆.对于活性剂增大焊缝熔深机理方面,提出了熔池表面张力改变理论、电弧收缩理论和热输入增加理论.本文总结了A?TIG焊在不同焊接母材方面、活性剂的引入方面、熔深增大机理方面的研究进展,分析了A?TIG焊研究应用方面仍存在的问题,并对A?TIG将来的研究方向进行了前景展望,以期为进一步完善A?TIG焊接方法和推动A?TIG在工业生产上的应用提供一定的借鉴.     

奥氏体不锈钢A-TIG焊工艺研究

目的研究焊接参数对焊缝成形和接头宏观组织的影响。方法改变焊接电流、焊接速度、焊接电压以及活性剂中的一个参数,固定其他3个参数不变,对奥氏体不锈钢进行焊接,分析其接头宏观形貌、组织和力学性能。结果随着电流、电压的增加,焊接接头的熔深和熔宽都在增加,随着焊接速度的增加,焊接接头的熔深和熔宽都在降低,在相同参数下,将不同活性剂下的A-TIG焊接头的熔深和熔宽进行比较,发现涂敷C4活性剂接头熔深最大达到4.29mm,而常规TIG焊接头熔深为1.38mm,涂敷C4活性剂的接头熔深为TIG焊的3.11倍,且熔宽也有所减小。结论 C4活性剂A-TIG最佳工艺参数为:I=175 A,U=14 V,v=80 mm/min,此时能将6 mm板材焊透,成形良好,在此工艺下焊缝等轴晶范围最大,焊缝组织最为细小。相比于TIG焊,涂敷C4活性剂接头强度系数提升4.1%。     

2219高强铝合金活性TIG焊工艺

采用单组分活性剂(AlF_3和LiF)、3组分(AlF_3+30%LiF+10%KF-AlF_3)和4组分(AlF_3+30%LiF+10%KFAlF_3+10%K_2SiF_6)混合组分活性剂进行2219高强铝合金直流正极性活性TIG焊(DCSP A-TIG),研究4种类型活性剂对焊缝表面成型、焊缝内部质量(气孔)、焊缝熔深、电弧形态、接头组织与力学性能的影响。结果表明:涂覆活性剂有助于去除2219铝合金表面的氧化膜,提高焊缝表面成型质量,涂覆4组分活性剂的DCSP A-TIG焊缝表面成型质量最佳;与变极性TIG焊(VPTIG)焊缝内部质量相比,DCSP A-TIG焊接方法可显著降低2219铝合金焊缝内部气孔的产生;AlF_3单组分活性剂可显著增大焊缝熔深,其电弧形态具有明显的拖弧现象;DCSP A-TIG焊焊缝组织具有与母材相同的组织组成物,电流对A-TIG焊缝组织影响较大,增大焊接电流,会造成接头晶粒组织粗大;涂覆4组分活性剂的DCSP A-TIG接头强度和伸长率最高,与VPTIG焊接头力学性能具有相近的技术指标。2219高强铝合金的DCSP A-TIG焊接方法具有很大的工程应用价值。     

粉煤灰复合活性剂在A-TIG焊中增加熔深的机理研究

为实现对工业废弃物粉煤灰的剩余价值利用,尝试以粉煤灰作为主要原料制备焊接复合活性剂,并在AZ91镁合金板上进行A-TIG焊.利用焊缝的电特性实时采集、焊接温度场采集、电弧力测试等手段研究活性剂对电弧影响,通过熔池Bi粒子示踪实验探究活性剂对表面张力温度梯度影响.结果 表明:与常规TIG焊相比,粉煤灰复合活性剂可以使焊缝熔深增深1.4倍,熔宽减小,深宽比是常规TIG焊的1.43倍.粉煤灰复合活性剂中氟化物的解离和电离吸热过程、带电粒子的电子扩散和复合过程可以促进电弧收缩,使焊接电压升高,热输入量提高.而活性剂中的氧化物既可以通过对电弧的机械压缩作用强迫电弧收缩,又可以通过电离产生的氧元素实现对熔池液态金属表面张力温度梯度系数的改变,提高熔池中心热输入.A-TIG焊AZ91镁合金熔深增加是电弧收缩理论和表面张力温度梯度改变理论共同作用的结果.     

粉末熔池耦合活性TIG焊接方法

提出了一种新型活性焊接方法——粉末熔池耦合活性TIG焊(Powder pool coupled activating TIG welding,PPCATIG)。该方法采用双层气体进行焊接,内层利用惰性气体保护钨极,外层通过自动送粉装置将活性剂粉末随保护气体送入电弧-熔池区域,增加熔深,提高焊接效率,实现机械化自动化焊接。针对SUS304不锈钢进行了直流正接PPCA-TIG表面熔深,通过与传统TIG焊对比,研究了SiO_2活性剂对电弧形态、焊缝成形、组织和力学性能的影响。结果表明:SiO_2能使电弧等离子体收缩、熔池金属流态改变,并且焊缝熔深能达到传统TIG焊的3倍以上,焊接效率明显提高。焊缝组织主要为奥氏体和铁素体,铁素体形态以骨架状为主。焊缝抗拉强度略低于母材,但相比传统TIG焊,焊缝屈服强度略有提高,其焊缝低温冲击韧性达到了传统TIG焊的96.8%,表现出了良好的力学性能。同时,采用该方法可有效避免活性剂粉末对钨极的污染。     

粉煤灰/二氧化硅活性剂在Q235钢A-TIG焊中的应用

为了探究粉煤灰作为A-TIG焊活性剂的可行性,以粉煤灰和不同含量的二氧化硅制备复合活性剂在Q235钢基体表面进行A-TIG焊,研究了复合活性剂成分含量对焊缝截面形貌、显微组织和元素分布的影响.结果表明:采用粉煤灰-40%SiO_2作为复合活性剂进行A-TIG焊时,可将6 mm厚Q235钢板一次性焊透,焊缝深宽比可达到0.85;焊缝出现明显的中间收缩倾向,呈"深口杯"状,可实现单道焊双面成型的效果;其焊缝柱状晶数目较多、组织排列规则且具有方向性,熔合区和热影响区组织均匀细小,可降低焊接母材的过热倾向;相对于100%SiO_2活性剂,Si元素的溶入量和溶入深度显著增加,这说明粉煤灰中其他成分的存在对Si元素溶入焊缝、进而增加焊缝熔深起到促进作用.采用粉煤灰-40%SiO_2为活性剂进行A-TIG焊时焊缝熔深的增加机理可能是以电弧收缩理论为主,但考虑到Al元素溶入较深且溶入量较多,粉煤灰中其他物相又十分复杂,在高温电弧作用下各物相之间相互反应放热致使电弧热输入增加、其他组分在熔池中改变了熔池表面张力温度梯度等均可能致使焊缝熔深增加.     

TC4钛合金焊接工艺研究

对TCA钛合金进行A—TIG焊和TIG焊,分析不同的焊接方法和焊接工艺参数对焊后钛合金熔深、熔宽和焊缝熔池区域显微组织的影响,运用了光学显微镜等,对A—TIG焊接头的力学性能、显微组织进行了分析研究。试验结果表明,和常规TIG焊相比,在相同的焊接参数下,A—TIG焊能够有效减小熔宽,显著增加熔深;A—TIG焊能够有效减少焊缝气孔数量;对于TCA钛合金的焊接,A—T1G焊比常规TIG焊具有较明显优势。     

有色合金A-TIG焊研究现状

活性化TIG焊(A-TIG焊)可以用于焊接不锈钢、碳钢、铝合金、镁合金、钛合金和镍基合金等材料。根据国内外关于A-TIG焊接技术研究、发展及应用的实际情况,综合论述了A-TIG焊接技术这一新型焊接方法在铝合金、镁合金、钛合金和镍基合金焊接领域中的研究现状。     

The mechanism of penetration increase in A-TIG welding

The mechanism of the increasing of A-TIG welding penetration is studied by using the activating flux we developed for stainless steel. The effect of flux on the flow and temperature fields of weld pool is simulated by the PHOENICS software. It shows that without flux, the fluid flow will be outward along the surface of the weld pool and then down, resulting in a flatter weld pool shape. With the flux, the oxygen, which changes the temperature dependence of surface tension grads from a negative value to a positive value, can cause significant changes on the weld penetration. Fluid flow will be inward along the surface of the weld pool toward the center and then down. This fluid flow pattern efficiently transfers heat to the weld root and produces a relatively deep and narrow weld. This change is the main cause of penetration increase. Moreover, arc construction can cause the weld width to become narrower and the penetration to become deeper, but this is not the main cause of penetration increase. The effects of flux on fluid flow of the weld pool surface and arc profiles were observed in conventional TIG welding and in A-TIG welding by using high-speed video camera. The fluid flow behavior was visualized in real-time scale by micro focused X-ray transmission video observation system. The result indicated that stronger inward fluid flow patterns leading to weld beads with narrower width and deeper penetration could be apparently identified in the case of A-TIG welding. The flux could change the direction of fluid flow in welding pool. It has a good agreement with the simulation results.     

Research on the Mechanism of Penetration Increase by Flux in A-TIG Welding

The mechanism of penetration depth increased by activating flux in activating tungsten inert gas (A-TIG) weldingwas studied by measuring the distribution of trace element Bi in the weld and monitoring the change of arc voltageduring A-TIG welding of stain     

活性剂在焊接中的应用及展望

综述了活性剂在A-TIG焊、钎焊、电子束焊、FBTIG焊、激光焊、以及CO2气体保护焊中的应用,探讨了活性剂在A-TIG焊、钎焊中的作用和机理,以及国内外活性剂的开发、应用和活化焊接技术的研究及发展中存在的问题和差距.     

AC TIG welding with single-component oxide activating flux for AZ31B magnesium alloys

Magnesium-based alloys are finding extensive applications foreground in aerospace and automotive applications. Weldability of magnesium alloys has recently been investigated with a variety of processes. In this article, the activating flux TIG (ATIG) welding of magnesium alloys with three single-component fluxes (TiO₂, Cr₂O₃ and SiO₂) under alternating current (AC) mode was studied. The effects of welding speed, weld current and electrode gap on the weld shape and the weld arc voltage in AC TIG welding with oxide fluxes were investigated on an AZ31B magnesium alloy substrate. The mechanisms of oxide fluxes on the arc shape and the arc voltage on the weld shape are discussed. The result showed that the TiO₂ and Cr₂O₃ increase the weld penetration of AC TIG welding of magnesium with good bead cosmetics. The SiO₂ increased the weld penetration with very poor formation of the weld surface. However, the arc voltage decreased with the used of TiO₂ flux, and increased with the used of Cr₂O₃ flux. The mechanism of TiO₂ and Cr₂O₃ fluxes increasing penetration should not accord with the “arc constriction”. It would comply with some potential effects of the flux interacting with the liquid metal of fusion zone.     

活性剂对铁素体不锈钢A-TIG接头熔深及组织性能研究

目的 选用430铁素体不锈钢作为研究对象,对比研究添加SiO2、TiO2、Cr2O3和未添加活性剂对A-TIG焊接接头显微组织和力学性能的影响。方法 采用3种活性剂涂覆在430铁素体不锈钢上进行A-TIG试验,分析活性剂对接头熔深、组织、性能、元素含量的影响情况。结果 同一焊接工艺参数下,活性剂的加入均能提高焊缝的熔深和深宽比,减少熔宽;其中,SiO2为活性剂时获得了最佳的焊缝几何形貌。同时,对比常规TIG焊接(未添加活性剂)接头的显微组织及力学性能可知,活性剂的加入并未改变焊接接头的显微组织且无新相的生成;活性剂的添加能够细化接头组织,从而使得接头硬度有所提高。结论 活性剂的加入能够显著增加铁素体不锈钢TIG焊缝熔深,改善接头组织,提高接头硬度。     

Effects of the Process Parameters on Austenitic Stainless Steel by TIG-Flux Welding

The effects of the process parameters of TIG （tungsten inset gas）-flux welding on the welds morphology, angular distortion, ferrite content and hot cracking in austenitic stainless steel were investigated. Autogenous TIG welding process was applied to the type 304 stainless steel through a thin layer of activating flux to produce a bead on plate welded joint. TiO2, SiO2, Fe2O3, Cr2O3, ZnO and MnO2 were used as the activating fluxes. The experimental results indicated that the TIG-flux welding can increase the weld depth/width ratio and reduce the HAZ （heat affected zone） range, and therefore the angular distortion of the weldment can be reduced. It was also found that the retained ferrite content within the TIG-flux welds is increased, and has a beneficial effect in reducing hot cracking tendency for stainless steels of the austenitic type weld metals. A plasma column constriction increases the current density at the anode spot and then a substantial increase in penetration of the TIG-flux welds can be obtained.     

Genetic-Algorithm-Based Computational Models for Optimizing the Process Parameters of A-TIG Welding to Achieve Target Bead Geometry in Type 304 L(N) and 316 L(N) Stainless Steels

The weld-bead geometry in 304LN and 316LN stainless steels produced by A-TIG welding plays an important role in determining the mechanical properties of the weld and its quality. Its shape parameters such as bead width, depth of penetration, and reinforcement height are decided according to the A-TIG welding process parameters such as current, voltage, torch speed, and arc gap. Identification of a suitable combination of A-TIG process parameters to produce the desired weld-bead geometry required many experiments, and the experimental optimization of the A-TIG process was indeed time consuming and costly. Therefore it becomes necessary to develop a methodology for optimizing the A-TIG process parameters to achieve the target weld-bead geometry. In the present work, genetic algorithm (GA)-based computational models have been developed to determine the optimum/near optimum process parameters to achieve the target weld-bead geometry in 304LN and 316LN stainless steel welds produced by A-TIG welding.