铝合金交流脉冲双面弧焊工艺试验及特点分析

通过工艺试验,详细分析了LYl2CZ铝合金板交流脉冲等离子弧（PA）-钨极氩弧（GTA）双面弧焊（DSAW）的工艺特点。通过与常规钨极氩弧焊和等离子弧焊工艺比较,发现该工艺可以显著增加熔深,减小焊后热变形,提高焊接生产效率。分别采用多孔喷嘴和单孔喷嘴进行了对比试验,其中采用多孔喷嘴能够有效防止双弧的产生,采用单孔喷嘴能够获得较大熔深。当采用小孔型交流脉冲双面弧焊工艺焊接铝合金时,由于小孔的存在,焊接过程中阴极雾化效果降低,影响焊缝成形及质量。     

薄板不锈钢旁路分流双面电弧高速焊接工艺分析

针对薄板不锈钢传统焊接方法焊接效率低、焊接缺陷多等问题,提出一种薄板不锈钢旁路分流双面电弧高速焊接方法。采用正面MIG-TIG背面TIG的双面焊接工艺,对船用2 mm厚的304不锈钢板进行焊接工艺机理研究。针对焊接效率提升问题,进行试验验证,对焊接过程中不同焊接速度和旁路电流对焊接质量的影响进行对比分析,并进行宏观组织和微观组织观察,通过拉伸试验验证焊缝接头力学性能的可靠性。结果表明,在施加旁路的情况下,正面旁路有效减小了母材的热输入,提升了焊接效率,并使焊缝热影响区组织得到较好的控制,达到细化晶粒的效果,从而减少焊缝咬边、塌陷等缺陷。创新点：(1)提出旁路分流双面电弧焊接工艺方法,对焊接过程中的热输入进行有效控制。(2)不锈钢薄板对接焊丝熔覆效率得到大幅度提升,有效解决焊接过程填丝效率低的问题。(3)焊接过程中焊缝热影响区组织和性能得到较好的控制。     

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.     

不锈钢PA-GTA双面弧焊工艺特点分析

详细分析了不锈钢等离子弧(PA)-钨极氩弧(GTA)双面弧焊(DSAW)的工艺特点,该工艺可以增加熔深,减小焊后热变形,尤其适用于中厚板的焊接.当小孔效应建立后,PA-GTA双面弧焊过程中的电弧均得到了不同程度的压缩,两焊枪之间的电弧电压出现下降趋势,节省了能源.形成小孔后,电弧穿过工件从工件内部进行加热,提高了热效率.表面张力、电弧吹力和电磁搅拌力均有利于获得较大的熔深,浮力有利于增加焊缝中间部位的宽度.     

低合金高强钢双面双弧焊热循环对组织性能的影响

针对低合金高强钢厚板焊研究了一种不清根高效焊接的新工艺--双面双弧焊(DSAW),即双面双脉冲TIG焊打底,双面双MAG焊填充.采用钻孔隐藏热电偶的方法对单TIG焊和双TIG焊打底的熔合区附近温度场进行了测量.结果表明,单TIG焊的t8/5和t8/3比双TIG焊的要小,双TIG焊前电弧对后焊道有预热作用,而后电弧对前焊道有二次热处理作用.单TIG焊缝和粗晶区组织为粗大的板条马氏体,而双TIG焊缝区组织是马氏体 针状铁素体,粗晶区的板条状马氏体组织比单TIG焊要小,微观硬度曲线分析表明单TIG焊打底的焊缝区和粗晶区的硬度比双TIG焊的硬度高.     

厚板钛合金等离子—钨极氩弧复合焊接接头组织与性能

针对16 mm厚TA2钛合金板材进行等离子打底+钨极氩弧焊盖面的复合焊(plasma-tungsten inert gas welding,P-T复合焊),采用小孔型等离子焊实现不开坡口单面焊双面成形。结果表明,焊缝的组织为少量锯齿形α-Ti+针状马氏体,未发现成分偏析与聚集、夹杂物及裂纹等缺陷。热影响区及熔合线为锯齿形α-Ti+板条马氏体组织。焊缝的抗拉强度达到486 MPa,与母材相当,且断裂位置位于热影响区。在较优的工艺参数下进行焊接,焊缝及热影响区的维氏硬度分别为175 HV和170 HV,均高于母材。因此P-T组合焊接能实现钛合金厚板焊接,在厚板钛合金焊接中具有广泛的应用前景。创新点： 首次采用等离子打底和氩弧焊盖面的复合焊接方法实现16 mm厚钛板无缺陷焊接。     

气流再压缩等离子弧焊接工艺初步探究

等离子弧焊接在中厚板焊接领域具有重要的应用前景.自主设计搭建了气流再压缩等离子弧焊接系统,开展了气流再压缩等离子弧焊接新工艺试验研究.通过焊接过程监测系统分析焊缝成形,温感扫描图可以比较准确的反映实际焊缝成形.针对8 mm厚的304不锈钢,焊接电流为150 A时,常规等离子弧焊接熔深为6.53 mm;气流再压缩等离子弧焊接可以完全熔透工件,且正面焊缝和背面焊缝成形良好.结果表明,相同电流条件下,与常规等离子弧焊接相比,气流再压缩等离子弧焊接电弧电压升高;气流再压缩等离子弧焊接可以提高焊接熔透能力.     

Effect of arc distance on temperature field and weld shape during double-sided arc welding

A new high efficiency welding method, double-sided double arc welding with double powers (DSAW-D), is developed for thick plate of low alloy high strength steel in this study. It is well known that the thermal cycles have an important influence on the microstructure, shape, stress, distortion and mechanical property. The DSA W-D method can control the tempernture field on a wide range by regulating the distance between two arcs, improve the rnicrostructure and prevent hot and cold cracking of high strength steel. But at present, the effect of arc distance on the temperature field and shape is not clear. Therefore, the paper researches the effect of arc distance on the temperature field and weld pool during DSA W-D using finite element method. The transient temperature field of different arc distance in DSAW-D is calculated.To verify the numerical results, the temperature is measured by the thermo-couple and the calculated results agree approximately with experimental data. Farther, the thermal property and mutual effect of double-sided arcs are investigated. The temperature distributions and weld pool profile at different arc distances are obtained. The results show that arc distance is a very important factor to affect the heat process.     

Mechanical properties and microstructure of pure nickel PAW and PAW-TIG welded joints

A plasma arc welding( PAW)-tungsten inert gas( TIG) hybrid welding process is proposed. And this paper investigated the microstructure and properties of pure nickel N6 joints by PAW-TIG hybrid welding. Compared with the conventional PAW method,the characteristic of PAW-TIG welding process is that there is no interaction between the two arcs.The addition of TIG can enhance the intrinsic high-efficiency peculiarity and the stability of the keyhole status of PAW. The joints made using PAW and PAW-TIG,respectively,were subjected to microstructural evaluations and tensile testing so as to analyze the effect of TIG arc energy on the microstructure and mechanical properties of these joints. The results of this investigation indicate that significant grain coarsening was observed in the weld metal( WM) and heat affected zone( HAZ)and it is found that the extent of grain coarsening increased with the addition of TIG arc. And the microstructure in hybrid joint,with wider weld width and the smooth surface,is coarser than in PAW joint. Furthermore,the microhardness and ultimate tensile strength( UTS) of hybrid joint is slightly lower than that of PAW joint. The fractograph observation shows that the fracturing mechanism of PAW joints ductile,while the hybrid welding joints exists as brittle-ductile fracture mode. The outcome of this work shows that in the condition of same deposited rate,TIG arc post-weld heat treatment can improve the welding efficiency and welding speed. The proposed PAW-TIG hybrid welding process is demonstrated to be suitable for welding nickel and its alloys in industry application.     

基于小波频带能的脉冲VPPA焊接熔透特征信息提取

焊缝熔透状态的监控对焊接过程质量控制和自动化生产的实现具有重要的意义。建立脉冲VPPA焊接系统,对脉冲VPPA焊接不同熔透状态的电弧电压进行小波分解,将其分解到不同频带,进行频带能量的计算,提取了与频带能量对应的熔透状态特征信息。研究结果表明：脉冲VPPA焊接电弧电压高频频带能量能够很好地反映焊缝熔透状态,当焊缝熔透状态发生变化时频带能量值产生突变,可作为脉冲VPPA焊接过程在线检测量,为脉冲VPPA焊接熔透实时控制提供一种新方法。     

铜钢异种材料等离子弧焊接头性能

采用LHM-200等离子弧焊机对1 mm紫铜与低碳钢异种材料进行了熔透型等离子弧焊试验,得到了内部无缺陷、外观成形良好的接头.观察了接头的显微组织,并分析了工艺参数对接头力学性能的影响.结果表明,焊缝区中心显微组织呈细胞群状,界面两侧的组织特征呈现显著的不同,焊缝与铜侧界面没有明显的熔合线,局部呈漩涡状,钢侧与焊缝连接处出现了明显的分界线;最佳工艺为焊接电流为65 A,焊接速度为0.4 cm/s,离子气流量为0.7 L/min,此时接头抗拉强度可达176 MPa,试样断裂于铜母材热影响区.     

双面激光打底焊根部熔合模拟及组织演变分析

提出了一种双面摆动激光错位同步焊接新工艺,用于厚板大钝边的自熔打底焊接,开展了不同激光间距下打底焊接试验,建立了双面激光打底焊接有限元模型,获取熔池形貌,并与试验焊缝形貌进行对比验证,在此基础上分析了接头粗晶区的焊接热过程及组织演变.结果表明,双面摆动激光错位同步焊接可以实现大钝边打底焊缝的良好熔透成形;与单面激光打底焊接相比,双面激光焊接粗晶区800 ~ 500 ℃的冷却时间(t_8/5)和800 ~ 300 ℃的冷却时间(t_8/3)延长;当激光间距不低于50 mm时,粗晶区发生重新奥氏体化. 单面摆动激光焊接粗晶区的显微组织为板条马氏体,双面摆动激光焊接粗晶区的显微组织为板条马氏体和板条贝氏体,而且随着激光间距的缩短,板条贝氏体含量逐渐增加;双面摆动激光错位同步焊接利于改善接头性能,降低冷裂倾向.     

铝/铜异种材料等离子弧熔钎焊搭接接头工艺分析

采用LHM-200等离子弧焊机和Zn-Al钎料对T2紫铜与LF6防锈铝异种材料进行了等离子弧熔钎焊,通过扫描电镜(SEM)和能谱分析仪(EDS)观察分析其接头显微组织和界面元素组成.结果表明,通过合理设置工艺可以得到较为理想的焊接接头,焊缝表面无裂纹、气孔等现象,搭接接头抗剪强度可达175.5 MPa;控制等离子弧焊工艺可以有效控制钎缝成形,提高接头性能,最佳参数范围为等离子气体的流量0.2,0.75 L/min,焊接电流45~55 A,焊接速度1.41~3.03 cm/s;在铜母材与钎料界面处是Al₂Cu和CuZn₂金属间化合物层;而在铝母材与钎料界面处为Al-Zn共晶组织;焊缝中心的是黑白相间的条纹组织,黑区为富铝区,白区为富锌区.     

交直流混合VPPA特性及铝合金立焊工艺

厚板铝合金变极性等离子弧(VPPA)穿孔立焊工艺中,由于焊接电流大,长时间焊接时钨极的烧损量大,严重影响厚板大结构自动焊接质量.为此提出了通过交直流混合输出减少钨极烧损,同时提高焊接质量的新型铝合金变极性等离子弧穿孔焊接方法.该方法在保证氧化膜清理的前提下,减小了因反极性时间过短电弧在极短时间内两次过零造成的等离子弧力下降和过大的感应电动势对开关器件的损害.其次交直流混合输出电弧具有低频调制效果,起到熔池振荡、细化晶粒的作用.在实现交直流混合VPPA软硬件功能基础上研究了交直流混合VPPA等离子弧力学特性、焊接过程稳定性及焊缝成形机理.通过对焊缝显微组织及焊缝成形检验发现,交直流混合输出时焊缝晶粒细化,焊缝成形美观,实现了减少钨极烧损和提高焊缝质量双重目标.     

SUS304/Q235B双金属冶金复合螺旋管激光-CMT复合焊+埋弧焊接头组织及性能

采用激光-CMT复合焊+埋弧焊的焊接工艺对SUS304/Q235B双金属冶金复合螺旋管进行了生产试制,利用OM,EDS研究了复合管焊缝微观组织特征及合金元素分布,同时检验了焊接接头的力学性能和耐腐蚀性能。结果表明,焊缝合金成分合理,合金元素稀释率低。内焊焊缝(CMT区域)微观组织为奥氏体+铁素体+碳化物析出相,内焊焊缝(LBW区域)微观组织为奥氏体+铁素体+马氏体,Q235B基层焊缝微观组织为铁素体+珠光体;焊接接头抗拉强度平均值为451 MPa,-10 ℃下焊缝及热影响区的冲击吸收能量平均值分别为167 J和236 J,焊接接头面弯、背弯180°拉伸面无裂纹(弯轴直径45 mm),焊缝硬度最高值为285 HV10;晶间腐蚀试验后,管体与焊缝弯曲180°拉伸面无裂纹(弯轴直径4 mm)。SUS304/Q235B双金属冶金复合螺旋管激光-CMT复合焊+埋弧焊接头的各项性能均符合相关标准的要求,能够满足饮用水输送工程的应用需求。创新点： 区别于传统螺旋焊管的双面埋弧焊,采用了激光-CMT复合焊(内焊)+埋弧焊(外焊)的工艺对SUS304/Q235B双金属冶金复合螺旋管进行焊接,形成了“Y+V”形的焊接接头形貌,减小了内、外焊缝的重合量,有效地控制了不锈钢复层一侧焊缝合金元素的稀释及碳钢基层一侧焊缝合金元素的过量裹入,避免了内、外焊缝高硬相的产生,提升了焊接接头的综合性能。     

Numerical simulation of dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates

The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates (1000mm × 700 mm × 50 mm)is numerically simulated using MSC.MARC.The effect of arc distance on the thermal cycle in weld zone during double-sided asymmetrical TIG backing welding is investigated.The results show that the workpiece experiencesdouble-peak thermal cycle in double-sided asymmetrical TIG backing welding.On the one hand,the fore arc has the preheating effect on the rear pass,and the pre-heating temperature depends on the distance between the double arcs,the heat input of fore arc,and the initial temperature of workpiece.On the other hand,the rear arc has the post-heating effect on the fore pass.The mutual effects of two heat sources decrease with the increase of arc distance.     

基于多信号检测的等离子弧焊接平台构建

焊接过程的准确检测是实现高效优质焊接的基础。实现等离子弧焊接过程的多信号检测对于指导等离子弧焊接工艺具有重要意义。文中搭建了基于多信号检测的等离子弧焊接平台,该等离子弧焊接平台包括等离子弧焊机和焊枪系统、机械运动机构、视觉检测系统、焊接过程监测系统、计算机控制系统等;通过视觉检测系统拍摄了等离子弧焊接电弧形态,测量出了喷嘴出口处的电弧直径与工件上表面电弧直径比值为0.64,证实了等离子弧焊接电弧挺度高,发散程度小;通过焊接过程监测系统,拍摄了焊缝温感扫描图,在线实时监测了等离子弧焊接焊缝成形,结果表明温感扫描图可以比较准确地反映等离子弧焊接的实际焊缝成形。     

大厚板双面双TIG电弧打底焊熔池成形特性

采用视觉图像监测法对新开发的双面双TIG电弧错位同步打底焊熔池成形特性进行了研究.结果表明,根部预留间隙是保证打底焊根部熔合的有效措施,可以实现大厚板不清根焊接.脉冲TIG焊是大厚板打底焊的优选方法,峰值期间电弧熔化能力强,坡口根部两侧边缘熔化良好.基值期间熔池迅速凝固,防止了下淌.双TIG电弧错位同步打底焊时,后电弧的加入导致两弧之间工件高温区增加,前电弧熔池拉长.焊缝宏观金相显示母材充分熔化,没有侧壁未熔合,焊缝正表面成形圆滑过渡,没有气孔、裂纹、夹渣、咬边等成形缺陷.     

超声复合焊接系统声场模拟及焊接电弧压力分析

提出了超声复合焊接空间中声场参数的分析方法,根据超声复合焊接特性构建了分析模型,利用COMSOL有限元分析软件模拟分析了声场参数随着发射端半径的变化情况,同时模拟分析了声场参数在不同电弧空间高度的变化规律.采用静态小孔法对不同焊接参数下稳定燃烧的直流U-TIG焊和普通TIG焊的电弧压力分布进行了测量.结果表明,U-TIG焊电弧压力峰值明显高于普通TIG焊,复合电弧能够提高焊接时熔池表面上方的电弧压力水平,但是随着电流增加,U-TIG焊和普通TIG焊电弧压力峰值的差值减小.分析认为大电流时,弧柱中心区域温度很高,电流密度很大,使TIG焊电弧压力峰值明显升高,而U-TIG焊电弧等离子流力受到气体流量的限制,电弧压力峰值增幅减小.     

工业纯钛光纤激光-MIG复合焊接工艺及性能

采用光纤激光与熔化极惰性气体保护电弧焊(MIG焊)复合焊接工业纯钛,分别对激光焊、MIG焊和复合焊接头的焊缝表面成形、横断面进行了观察,并进行了激光焊和复合焊接头的拉伸试验及杯突试验.结果表明,复合焊的电弧稳定性比MIG焊显著提高,焊接速度可提高7倍;复合焊与激光焊接头的抗拉强度高于母材;复合焊接头的杯突值优于激光焊接头的杯突值,这是因为复合焊焊缝的微观组织有利于接头的塑性.因此,采用光纤激光-MIG电弧复合焊接方法很好地实现了工业纯钛的高速焊接,焊缝成形良好,接头的塑性优于单一激光焊的塑性.

Abstract：

Fiber laser-metal inert gas (MIG) arc hybrid welding was used to weld the commercial pure titanium (CP-Ti). The weld appearance, cross section, tensile strength, Erichsen value and microstructure of the CP-Ti welded joints were studied. The results show that the arc stability is substantially improved and the welding speed can be increased to 7 times by fiber laser-MIG hybrid welding. The welded joints by laser welding and the hybrid welding exhibit the higher ultimate tensile strength than those of the base metal. In addition, the welded joint by the fiber laser-MIG hybrid welding has higher Erichsen values than that by laser joints. The difference in plasticity is attributed to the microstructure changes in the welded joint of hybrid welding. Thus, the fiber laser-MIG hybrid welding of CP-Ti can be carried out suecessfully at higher welding speed with a good combination of weld bead appearance and plasticity.