Electromagnetic Characteristic of Twin-wire Indirect Arc Welding

Traditional welding methods are limited in low heat input to workpiece and high welding wire melting rate. Twin-wire indirect arc（TWIA） welding is a new welding method characterized by high melting rate and low heat input. This method uses two wires one connected to the negative electrode and another to the positive electrode of a direct-current（DC） power source. The workpiece is an independent, non-connected unit. A three dimensional finite element model of TWIA is devised. Electric and magnetic fields are calculated and their influence upon TWIA behavior and the welding process is discussed. The results show that with a 100 A welding current, the maximum temperature reached is 17 758 K, arc voltage is 14.646 V while maximum current density was 61 A/mm2 with a maximum Lorene force of 84.5 ~tN. The above mentioned arc parameters near the cathode and anode regions are far higher than those in the arc column region. The Lorene force is the key reason for plasma velocity direction deviated and charged particles flowed in the channel formed by the cathode, anode and upper part of arc column regions. This led to most of the energy being supplied to the polar and upper part of arc column regions. The interaction between electric and magnetic fields is a major determinant in shaping TWIA as well as heat input on the workpiece. This is a first study of electromagnetic characteristics and their influences in the TWIA welding process, and it is significant in both a theoretical and practical sense.

Q450NQR1耐候钢激光填丝焊与MAG焊接头组织与性能对比

通过对Q450NQR1高强度耐候钢进行激光填丝焊和MAG焊对接工艺试验,研究了两种焊接方法下焊接接头微观组织及力学性能,并对拉伸试件断口进行扫描分析。研究表明,激光填丝焊和MAG焊接头焊缝区微观组织以粒状贝氏体为基体,伴有先共析铁素体及少量的珠光体。两种焊接方法的接头显微硬度从焊缝到母材整体呈下降趋势,激光填丝焊接头热影响区宽度较窄,熔合线是硬度最高位置,其硬化区平均硬度整体高于MAG焊接头同区域。两种焊接方法下试件弯曲性能良好,拉伸试件断裂位置均在母材,激光填丝焊接头具有更高的强度承载。拉伸断口扫描发现,断口均呈现典型的微孔聚集型韧性断裂特征。

薄板激光-电弧复合焊与双丝MAG电弧焊的接头缺陷对比分析

船用薄板拼板常采用传统的埋弧焊或焊条电弧焊,但存在焊接变形大和焊接效率低的问题。激光-电弧复合焊和双丝MAG电弧焊作为新型焊接方法,具有焊接速度快、焊接变形小、焊接道数少,以及可单面焊双面成形等优点,在提高焊接速度和生产效率的同时能够显著减小焊接变形。通过介绍激光-电弧复合焊和双丝MAG电弧焊两种方法拼接6mm厚的AH36钢板的焊接工艺,并对出现的焊接缺陷进行比较。结果表明:拼接薄板时,激光-电弧复合焊高速高效和防止变形的优势更为突出,但是激光-电弧复合焊比双丝MAG电弧焊更易出现气孔、飞溅、咬边及未熔合的问题;两种焊接方法均会出现反面成形不良的问题,不易出现裂纹和未焊透问题。通过对比分析,加深对激光-电弧复合焊和双丝MAG电弧焊方法的理解,同时便于船厂对可能出现的缺陷提前进行干预,选取合适的缺陷检测方案,也为新工艺的开发提供参考。

基于VMD的MAG焊输入端电信号频域分析

通过电信号采集平台,对焊机输入输出端电信号进行同步采集.分析弧焊电源整流电路,对输入电信号进行整流处理得到输入电压与电流,最终计算得到弧焊电源的输入功率.经过对比发现输出电流与瞬时输入功率峰值变化趋势基本一致.论述了变分模态分解(VMD)原理及方法,并对瞬时输入功率进行分解,得到一系列特征BLIMFs信号.通过对不同过渡模式(大滴过渡、短路过渡和混合过渡)下瞬时输入功率信号、特征IMF信号和焊接输出电流信号在频域上的对比分析,发现VMD能够有效得到低频(IMF1)、中频(IMF2)和高频信号(IMF3),且中频和高频信号表现出了焊机不控整流的脉动信息(300 Hz)以及电网的干扰.而低频IMF1信号与焊接输出电流信号频域一致性良好,并在时域上也有良好的一致性.结果表明了通过对输入瞬时功率的VMD,其低频分量能够有效表征焊接过程,从而为从输入端评定过渡过程稳定性提供了一种新思路.

MH600DP与MH540FB双相钢MAG焊焊接性研究

通过碳当量和冷裂纹敏感系数计算,以及硬度、金相组织检测等试验方法,对汽车轮辐和轮辋用钢热轧马氏体双相钢MH600DP和贝氏体双相钢MH540FB的焊接性,以及MAG焊角接接头焊缝组织、显微硬度分布进行了研究。研究成果具有一定的现实意义和应用价值。

Microstructure and mechanical properties of twin-wire arc spraying Ni-Swt.% AI coating on 6061-T6 aluminum alloy

Thermal sprayed Ni-5wt.% Al coating was fabricated on the substrate of 6061-T6 aluminum alloy by twin-wire arc spraying. Experimental results indicated that the average value of bond strength was around 46. 90 MPa, the average hardness was 240 HV and the average value of surface roughness was about O. 14 mm. Friction and wear test results showed that the dry friction coefficient of Ni-5wt.% Al coating firstly decreased, and then tended to a slight increase after 200 cycles. In the early abrasion stage, adhesion wear played the key role for wear mechanics of Ni-5wt.% Al coating, but gradually abrasive wear became to replace adhesion wear.

不同保护气成分对B10合金MIG/MAG焊接接头组织和性能的影响

为了研究不同焊枪保护气对B10合金MIG/MAG焊接接头组织和性能的影响,在氩气中分别添加了氦气和二氧化碳气体,并对3种焊枪保护气体下B10合金MIG/MAG焊接试板进行了接头微观组织、力学性能、工艺性能、腐蚀性能等测试。结果表明:3种保护气体下的焊接接头的焊缝组织均为枝晶状α相,热影响区组织均为孪晶α相,无明显区别;接头抗拉强度平均值分别为344 MPa、345 MPa和339 MPa,断裂位置均发生在母材,均高于母材标准下限值;在弯心直径等于4倍试样厚度、弯曲角度为180°的条件下弯曲性能良好;焊缝及热影响区的硬度相较于母材均有所下降;3种保护气体下的焊接试样的均匀全浸腐蚀速率相近,但在海水冲刷腐蚀试验中,97.5%Ar+2.5%CO_(2)保护气体试样腐蚀量最高,99.99%Ar保护气体试样腐蚀量次之,80%Ar+20%He保护气体试样腐蚀量最小。

Twin-wire Submerged Arc Welding Process of a High-strength Low-alloy Steel

The measurement of thermal cycle curves of a high-strength low-alloy steel （HSLA） subjected twin-wire submerged arc welding （SAW） was introduced. The thermal simulation test was performed by using the obtained curves. The impact toughness at -50 ℃ temperature of the simulated samples was also tested. OM, SEM and TEM of the heat-affected zone （HAZ） of some simulation specimens were investigated. The results showed that the HSLA endured the twin-wire welding thermal cycle, generally, the low-temperature toughness values of each part of HAZ was lower than that of the parent materials, and the microstructure of coarse-grained zone（CGHAZ） mainly made up of granular bainite is the reason of the toughness serious deterioration. Coarse grain, grain boundary carbide extract and M-A island with large size and irregular polygon, along the grain boundary distribution, are the reasons for the toughness deterioration of CGHAZ. The research also showed that selected parameters of twin-wire SAW can meet the requirements to weld the test steel.

不锈钢CMT焊接与MAG焊接工艺对比研究

选用2mm厚X2CrNiN18-7不锈钢进行CMT与MAG焊接工艺对比试验研究。主要从焊缝成形、接头金相、力学性能、焊接飞溅和焊接变形等方面对比分析以上两种工艺的不同之处。结果表明:两种焊接方法的焊缝都是典型的熔化极气体保护焊焊缝成形,二者主要的组织成分都以奥氏体为主,且有少量铁素体。由于MAG焊接热输入高,特征区域与CMT焊接相比缺少部分熔化区和等轴晶区。CMT焊接所得焊缝强度和伸长率高于MAG焊接,焊接飞溅仅为MAG焊接的20%左右,且同种外部条件下同类接头优化工艺CMT焊接变形比MAG焊接小,最大焊接变形约为MAG焊接的70%。

Study on twin-wire pulsed MIG welding power supply based on DSP and CAN

A design proposal for twin-wire pulsed MIG welding power supply based on DSP （ digital signal processor） and CAN （ controller area network ） is put forward. By ase of the CAN bus, the synergic control between the master and slave power supplies can be realized. And in this way, their peak currents can be guaranteed to be alternative and the interference between the two arcs can be decreased efficiently. The hardware design, software design and relative tests are provided in this paper. Tests show that the power supply can meet the design requirements of twin-wire welding.

Arc characteristics of twin-wire indirect arc gas shielded welding

Twin-wire indirect arc gas shielded welding is a novel welding method. By recording the arc shape and welding parameters, the effects of welding parameters and included angle on arc characteristics are discussed in this paper. The experimental results show increasing welding current can prompt centralized and straight of arc due to increasing plasma force and electric magnetic pinch effect. Increasing arc voltage can increase the size and brightness of the arc, as a result of increasing arc energy. The reducing of included angle increases the electric magnetic pinch effect, the arc becomes slender and supplies higher energy. It is thought the smaller included angle is beneficial to obtain perfect weld bead.

Inverter power supply system for high-power twin-wire pulsed GMAW

A type of novel inverter power supply system for high-power twin-wire pulsed gas metal arc welding （GMAW） is presented mainly for dealing with the disadvantages of the conventional power supply for twin-wire pulsed GMA W of which the output power is generally difficult to increase due to limitations of the power of semiconductors and the power density of magnetic devices. In the power supplies for the master and slave arcs, the digital signal processor （DSP） TMS320F28335 is used to form the DSP- based synergic control system for parallel high-power pulsed GMA W, which achieves high-power output of two parallel inverters controlled by a single DSP ; master-slave communication is achieved by using e controller area network （eCAN）module of DSP, thas realizing anti-phase pulse output of high-power twin-wire pulsed GMA W and reducing the interference between twin arcs. The experiment results demonstrate that the designed inverter power supply system for high-power twin-wire pulsed GMAW can bring about high-power efficiency of welding, stable welding process and proper formation of welds.

高功率激光-MAG复合焊接成形稳定性

采用激光-MAG(Metal active gas arc welding)复合焊接工艺,以焊缝表面成形、焊缝纵截面形貌和熔深波动程度为工艺稳定性评价依据,借助高速摄像系统和图像处理方法,对焊接过程中飞溅和等离子体两种关键过程信息进行特征识别和定量化表征,系统地研究激光功率从5 kW提高到30 kW时,焊接过程关键特征信息与焊接过程稳定性之间的关系。结果表明,随着激光功率的增加,焊缝表面成形出现周期性“上凸-下凹”现象,焊缝内部裂纹和熔深变化特征也随之周期性变化;等离子体面积和飞溅面积均随激光功率的提高呈增加趋势,且两者波动程度和熔深波动程度均呈正相关;等离子体面积增加会导致激光传输过程中能量衰减程度的加剧,使焊缝熔深增加趋势逐渐变缓,其波动程度是影响焊接过程稳定性的关键因素之一。

Twin-wire SAW welding of 70 kg class high strength steel

The twin-wire SAW welding process was investigated using Baosteel 70 kg class high strength steel, and the properties of the joints were studied using conventional single and double-faced grooves as well as an optimized groove. The results showed that by using an optimized double-faced groove, a small root face, and no back gouging, a small welding heat input was achieved and thus the joint strength and toughness were improved significantly. Also, removing back gouging reduced the labor required in the process. The weld reinforcement and deformation were observed to be rather small.

316L中厚不锈钢板MAG焊接头组织及性能研究

文中采用ER316L实心焊丝对20 mm厚316L不锈钢板进行熔化极活性气体保护焊(MAG),采用小电流多层多道焊制备了316L不锈钢板焊接接头,研究结果表明:奥氏体+10%铁素体构成了焊缝的稳态组织,热影响区为单相奥氏体,且奥氏体晶粒无明显的粗大现象;316L不锈钢焊接接头具有较高的强度和良好的韧性,接头强度高于母材316L钢的强度,接头弯曲位置无气孔和开裂现象。

Q345B钢MAG焊与激光-MAG复合焊对比研究

对4 mm和8 mm厚的Q345B试板分别进行MAG焊和激光-MAG复合焊的工艺试验研究,分析焊缝成形,检测焊接接头宏观形貌、拉伸性能和弯曲性能。结果显示:相对于常规MAG焊,激光-MAG复合焊能够实现单面焊背面无垫板的自由成形;焊接速度显著提高,焊接作业效率提高一倍以上;焊材消耗减少,仅为MAG焊的22%~27%;焊接热输入小,焊后工件变形显著减小;焊接接头的拉伸和弯曲性能合格,满足实际工程应用要求。

Q345E薄板高频脉冲MAG对接焊工艺及数值模拟

文中针对板厚为3 mm的Q345E低合金高强钢的低应力、小变形焊接工艺进行研究。采用打底焊模式的高频脉冲加短路熔滴过渡形式和电弧冷焊方法进行焊接。利用ABAQUS有限元分析软件的热-弹-塑性法,进行焊接温度场、应力场与焊接变形仿真分析,并对焊接热循环、焊接残余应力与焊接变形的变化进行测试,结果如下:打底焊模式0 mm间隙工况与电弧冷焊模式1 mm间隙工况的焊缝成形形貌良好,无裂纹、气孔、夹渣等焊接缺陷;在选择焊接方法时,0 mm间隙可选打底焊,1 mm间隙可选电弧冷焊;当试板正、背面受热不同,冷却过程中收缩程度也不一致,产生角变形,变形特征确定后,可通过减小热输入,减小正、背面受热差值来减小变形;纵向残余应力比横向残余应力相对较大,纵向残余应力正背面差值较小,横向残余应力正背面差值较大,应力场模拟特征与实测基本一致。

大型容器支承架ZQ460高强钢脉冲MAG焊工艺及接头组织性能研究

针对大型容器轻量化发展和节能降本需求,选用ZQ460高强钢作为某大型容器支承架结构材料。通过分析ZQ460高强钢的可焊性,采用脉冲MAG焊工艺对其进行不同热输入条件下的焊接性试验,并分析热输入对接头微观组织、力学性能和抗裂性能的影响。结果表明,热输入与接头的微观组织与力学性能密切相关,随着热输入增加,焊缝区先共析铁素体比例逐渐增多,针状铁素体尺寸增大,侧板条状铁素体比例减少;热影响区组织特征为多个方向各异的马氏体板条簇集。焊接接头室温拉伸性能呈现下降趋势,但断在焊缝区,仍远高于母材技术要求;焊接接头的侧向弯曲性能在热输入为12~16 kJ/cm范围内,在弯曲角度为180°时没有裂纹产生。为了确保焊接接头的综合性能良好,建议将焊接热输入控制在12~16 kJ/cm以内。

海洋环境下E690低合金高强钢MAG焊接接头热影响区耐腐蚀性能研究

随着海洋石油开采技术的发展,高强度钢焊接接头的耐腐蚀性能成为关键问题。为研究E690低合金高强钢MAG焊接接头热影响区(HAZ)在模拟海洋环境下的腐蚀行为,并分析其腐蚀机理,并使用3.5%NaCl溶液作为腐蚀溶液进行浸泡试验。通过光学显微镜、扫描电镜和能谱分析等手段,观察和分析HAZ不同区域的微观组织、力学性能、腐蚀形貌和腐蚀产物成分。结果表明,HAZ不同区域的腐蚀程度由大到小依次为过热区(GRHAZ)>正火区(CHAZ)>混晶区(CGHAZ)。GRHAZ内的腐蚀产物最少且分布均匀,未产生大面积腐蚀,腐蚀产物主要以Fe_(3)O_(4)和Fe_(2)O_(3)两种化合物为主,结构表现为团状和柱状。CHAZ和CGHAZ的腐蚀产物相对较多,且分布不均匀,其中CHAZ的局部位置出现加重腐蚀现象。焊接接头设计时应充分考虑HAZ的腐蚀敏感性,并采取相应的防护措施,以保证海洋平台的安全性和可靠性。

Q355B钢与Q345B钢MAG焊焊接接头力学性能对比研究

利用MAG焊,选用合适的焊接参数对其LGQ355B钢与LGQ345B钢进行焊接工艺试验,对比两种钢材在相同焊接条件下焊接接头的力学性能。结果表明:二者母材相比较,LGQ355B钢比LGQ345B钢具有较高的抗拉强度、屈服强度,平均高出30MPa,而LGQ345B钢具有较好的塑性和冲击韧性,并且二者母材纵向冲击性能明显要优于横向冲击性能。二者焊接接头相比较,其接头力学性能均满足标准要求,主要与母材本身及所选用焊丝的特性有关系,由于LGQ345B钢本身强度比LGQ355B钢低,其焊接接头表现出高强匹配,并且焊缝中心冲击韧性优于LGQ355B钢,因此二者钢材整体焊接接头焊缝中心冲击韧性要优于母材。通过研究,在日常结构件的制造过程中采用新标准下的Q355B钢与旧标准下的Q345B钢相比较,二者焊接工艺、焊接接头性能差异不是十分明显,焊接过程无需区别对待,可进行正常替代,同时为新标准下Q355B钢的焊接提供理论指导。