Simulation of Weld Depth in A-TIG Welding with Unified Arc-electrode model

Calculations have been made for weld depths occurring for TIG welding activated by a flux over the surface of the weld pool. In this case, the flux introduces an electrically insulating layer over the outer regions of the weld pool surface. There is then an increase in the current density at the surface of the centre of the weld pool with a consequent increase in the J×B forces, which drive a strong convective flow of the molten metal downwards, tending to make a deep weld. For a flux which produces an insulating layer for all but a central region of radius 2 mm, the calculated weld depth is 7 mm, and an arc spot is predicted at the centre of the weld pool surface. As yet we have not resolved the reason for significant differences that exist between our measurements of weld depth and the theoretical predictions.

Effects of fluxes with single component on weld depth in A-TIG welding of magnesium alloy

The effects of fluxes with single component on weld penetration depth in TIG welding of magnesium alloy were investigated. Seven kinds of halides were selected as the activating flux in the experiments. The effects of coating quantity of these fluxes on weld depth-to-width ratio were also studied. The results show that all of the selected halides can increase the weld depth under the same welding conditions compared with conventional TIG welding. The increase of penetration is different for the fluxes with different component. Among them, the flux of CdCl2 is the best, which can increase up to 334% of weld depth compared with the conventional TIG welding.

Effects of process parameters on the depth-to-width ratio of flux-cored wire underwater wet welding

The effects of process parameters on the depth-to-width ratio （D/W） of flux-cored wire underwater wet welding with a certain type of homemade .flux-cored wire are studied. It is found that the welding .speed, wire feeding speed and torch oscillating amplitude hare significant effects on the dopth-to-width ratio （D/W） of welds. The D/W ratio of welds increases significantly with the increase of welding speed without the oscillating of welding torch. It increased （from 0. 14 to 0. 26 ） with the increase of wire feeding speed while the torch oscillating. And it decreased linearly with the increase of torch oscillating amplitude. However, the influelwe of oscillating speed, wire extension and welding voltage on the D/W ratio of welds was not obvious.

RELATIONSHIP BETWEEN PLASMA OPTIC SIGNAL AND PENETRATION DEPTH FOR PARTIAL-PENETRATION LASER WELDING

Through sampling and analyzing of plasma optic signals of 400-600 nm emitted from partial-penetration laser welding processes, how the penetration depth is related to the welding parameter and the plasma optic signal is studied, Under the experimental conditions, the plasma optic signal has good response to variety of the weld penetration, and the signal＇s RMS value increases with the penetration in a quadratic curve mode. The inherent relation between the plasma optic signal and the penetration depth is also analyzed. It is also found that, between the two common parameters of laser power and welding speed, laser power has more influence on penetration while welding speed has more influence on weld width. The research results provide theoretic and practical bases for penetration real-time monitoring or predicting in partial-penetration laser welding,

Influence of tool plunge depth and welding distance on friction stir lap welding of AA5454-O aluminum alloy plates with different thicknesses

AA5454-O aluminum alloy plates with thicknesses of 1.4 and 1.0 mm were friction-stir-lap-welded (FSLWed).The influences of the tool plunge depth and welding distance on surface appearance,macrostructure and mechanical properties of the FSLWed plates were experimentally investigated.The tensile shear load of the FSLWed plates was compared with that of the adhesive-bonded plates.Defect-free FSLWed zones were successfully obtained in all the tool plunge depths and the welding distances.The FSLWed zones exhibited the relatively smooth surface morphologies.Under all the FSLWed conditions,the FSLWed zone exhibited higher average hardness than the base metal.In addition,the upper plate exhibited a higher average hardness than the lower plate,although there was no special tendency in spite of the change in the tool plunge depth and the welding distance.The maximum tensile shear load of the FSLWed plates was much higher than that of the adhesive-bonded aluminum alloy plate.Especially,under the FSLW condition of the plunge depth of 1.8 mm and the welding distance of 40 mm,the tensile shear load of the FSLWed plate reached a level about 41% greater than that of the adhesive-bonded aluminum alloy plate.In addition,the maximum tensile shear load of the FSLWed plate was increased with the increase of the welding distance.

Effects of strength matching and crack depth on the fracture parameters for welded joints

Fracture parameters of welded joints with different strength matching and crack depth in weld metal are investigated by using the methods of elastoplastic finite element analysis and three point bend specimen test. The results show that for shallow crack, the plastic zone turns large in loading process, and the fracture toughness turns high. The extent of the plastic zone of overmatched joint is larger than that of undermatched joint because it will extends to parent metal from the weld metal in loading process for the same CTOD value. The plastic zone of undermatched joint is restricted within the weld, and the size of that is small. Overmatched joint shows the fracture behaviour of shallow crack may more easily than the undermatched joint, while the two sorts of joint specimens have the same crack depth. Therefore, the fracture-resistant capability of overmatched weld is better than that of undermatched weld. when the toughness of weld metals is similar for both overmatched and undermatched joints.

激光焊OCT熔深测量去噪及数据拟合方法研究

为了解决激光焊接熔深在线检测及光学相干光层析成像(OCT)熔深检测信号噪声多的问题,采用了一种百分位滤波加移动平均算法的熔深曲线拟合方法。通过光学相干光层析成像系统对304不锈钢匙孔焊过程进行了熔深在线检测,在使用百分位滤波从原始散点数据中提取出百分位熔深曲线过程中,发现该方法提取的百分位熔深曲线存在尖峰干扰噪声,通过移动平均算法对百分位熔深曲线进行低通滤波处理,最终从原始散点数据中提取拟合出OCT熔深测量曲线。结果表明,将OCT熔深测量曲线与焊缝纵抛面的实际熔深曲线进行对比,该方法获取OCT熔深测量曲线的测量精度最大提升了15%。该方法能从OCT原始散点数据中有效提取拟合出更为准确的OCT熔深测量曲线。

铝/钢铆接辅助搅拌摩擦焊搭接接头组织与力学性能分析

目的利用搅拌摩擦焊技术对4mm以上厚度的铝/钢板材进行搭接焊接时,容易出现沿厚度方向温度梯度变化大、工艺窗口急剧变窄等问题,难以获得高质量的焊接接头。针对以上问题,采用铆接辅助搅拌摩擦焊的方法,以提高4mm以上厚度铝/钢板材搭接接头的力学性能。方法采用铆接辅助搅拌摩擦焊的方法实现了7mm厚6061铝合金板和8mm厚Q345钢板的搭接;研究了下压量对接头焊核晶粒尺寸、抗剪切力和显微硬度的影响,并分析了接头界面显微组织。结果随着下压量的增大,各接头焊核晶粒尺寸均呈现先减小后增大的趋势,其中矩形槽焊核晶粒尺寸由11.1μm减小至9.6μm后又增大至12.7μm,不开槽焊核晶粒尺寸由11.7μm减小至10.2μm后又增大至12.4μm。金属间化合物(IMC)层厚度随下压量的增大而增大,接头抗剪切力呈先增大后减小的趋势,当下压量为0.3mm时,矩形槽接头和不开槽接头抗剪切力均达到最大值,分别为17600N和15700N,并且在下压量为0.3mm时矩形槽接头和不开槽接头焊核区平均显微硬度均达到最大值,分别为81.1HV和76.8HV。结论在焊接速度为100mm/min、搅拌头转速为600r/min、轴肩下压量为0.3 mm时,利用铆接辅助搅拌摩擦焊可以提高搭接接头的力学性能,能够有效解决以往4mm以上厚度板材搭接接头力学性能较差的难题。

Welding depth measurement for different mode lasers using optical coherence tomography

Optical coherence tomography(OCT)allows a direct and precise measurement of laser welding depth by coaxially measuring the keyhole depth and can be used for process monitoring and control.When OCT measurement was taken during single-beam laser welding,the keyhole instability of aluminum welding resulted in highly scattered OCT data and complicated the welding depth extraction methods.As a combination of an inner core beam and an outer ring beam,a novel adjustable ring mode(ARM)laser for producing a stable keyhole was applied to the OCT measurement.Different ARM laser power arrangements were conducted on aluminum and copper.The results indicated that the ring beam greatly improved the stability of the core beam-induced keyhole,and smooth welding depth can be extracted from the concentrated OCT data.

基于变速GTAW焊接温度场解析模型的熔深预测研究

焊接热过程解析模型是一种能够直观反映焊接过程中工件内部的热行为、明确焊接工艺参数与熔池形貌间的物理关系、快速计算得到熔深的方法.目前常用的焊接温度场解析模型通常将电弧近似为一个功率恒定的匀速运动热源进行计算,而非参考实际焊接过程,即通过实时调整焊接热输入(焊接电流或焊接速度)来保证熔透.因此,目前的焊接温度场解析模型并不适用于焊接熔透控制.为了使解析模型能够计算时变速度下的熔深,本文针对钨极氩弧焊(GTAW)工艺建立了适用于计算时变焊接速度的焊接温度场解析模型.首先以匀速移动点热源的温度场解析模型为基础,推导出了时变焊接速度移动点热源在热源作用时间内引起的温度变化公式,通过连续性证明验证了公式的连续可积性并进一步推导出了适用于时变焊接速度运动单椭球热源的焊接温度场解析模型.为了提高计算速度,减少计算量,采用坐标变化方法实现了热源及其附近温度场的快速求解.基于数值积分法得到了解析模型求解方法,实现了熔池温度场的准确计算,并通过提取等温线实现了熔深和熔宽的预测.最后,通过工艺试验验证了解析模型的精度.结果表明:在0~4 s阶段,计算熔深基本与实际测得的熔深相同,误差控制在6%以内;在速度发生改变的4~16 s阶段,由于热源系数不再适用,计算误差增大,但熔深计算误差仍控制在17%以内,熔宽计算误差在12%以内.因此,建立的焊接温度场解析模型基本可以满足时变速度下的熔深预测.

多波环形激光器密封钉焊接工艺优化

随着新能源汽车行业的发展,对动力电池焊接质量提出了更高要求。为解决铝合金电池密封钉采用传统激光焊接时出现的裂纹、气孔等缺陷问题,并提高生产效率,采用自主研发的多波环形光斑光纤激光器对2 mm厚的3003铝合金盖板和0.95 mm厚的密封钉进行焊接,研究了在一定焊接速度下内外环焊接功率、离焦量等主要工艺参数对焊缝成形的影响。试验结果表明,在40 mm/s焊接速度下,光纤(内环)功率500 W,半导体(外环)功率1 700 W,离焦量1.5 mm时,焊缝熔深达0.6 mm,熔宽1.2 mm,此时焊接效果最优,焊缝各位置熔深一致性高,焊接飞溅极小且无炸点、气孔、裂纹等缺陷。通过样品焊接试验,验证了该焊接工艺的稳定性和可靠性。

铅酸蓄电池T2型端子烧焊结构研究

铅酸蓄电池用T2型端子在使用中有时会被接线卡子卡裂,造成端子爬酸、漏液的现象。端子烧焊深度浅是造成端子被卡裂的一个非常关键的因素。针对端子烧焊深度浅的问题进行原因分析,对端子烧焊结构进行改进,并通过试验验证结构改进后的端子烧焊效果,提高了改进后的端子烧焊深度及其稳定性,保证了蓄电池使用中的可靠性。

厚板双面四丝单道埋弧焊接工艺参数设计及应用

结合焊缝熔深与四丝单道埋弧焊一丝焊接参数、钢板壁厚、坡口深度的函数关系,及焊丝填充面积与四丝单道埋弧焊一丝~四丝焊接参数、坡口深度、坡口角度的函数关系,设计厚板双面四丝单道埋弧焊接的焊接坡口尺寸及对应的焊接参数。依据此参数进行32 mm、40 mm和50 mm厚板双面四丝单道埋弧焊接试验。结果表明,设计的焊接工艺参数既可保证厚板大钝边尺寸双面焊接焊透,又能保证厚板大坡口截面填满,并可获得良好的焊接质量。

基于船用涡轮增压器焊接涡轮设计参数的仿真分析研究

摩擦焊工艺已广泛应用于机械加工领域,船用涡轮增压器产品已大量使用摩擦焊焊接工艺,本文针对船用涡轮增压器转子系统的焊接涡轮进行研究,分析了焊接涡轮在倒角为3mm、4mm、5mm、开孔深度为12 mm、16 mm、19 mm、20 mm、25 mm下涡轮的应力情况。结果表明,焊接涡轮开孔深度可选择12~16mm,涡轮总体应力变化趋势较为缓和,有利于堆放焊接加工时形成的焊渣;倒角对涡轮应力受开孔深度的影响较小,但根据加工经验来看,倒角建议选择倒角为4mm。该研究结果进一步确定了船用涡轮增压器焊接涡轮机械加工的初步参数,对指导摩擦焊接加工具有重要意义。

动力电池焊接熔深在线监测与闭环控制

采用光学相干层析(OCT)对焊接熔深进行在线监测,研究了OCT监测技术的稳定性及焦距自适应性。结果表明:OCT监测的熔深结果与金相结果吻合度高,其误差不超过3.65%。OCT技术对焊接工况的变化不敏感,随着焊接功率、焊接速度及保护气流量的变化,OCT监测的熔深结果误差稳定在0.24%~3.65%之间。在±2.5mm的波动范围内,不同高度焊件OCT监测的熔深标准差仅0.072mm,其过程能力指数CMK达3.51。由此证明,OCT熔深监测技术具有优异的抗干扰能力及焦距自适应性,可以实现对焊接熔深的闭环控制。

动子磁极表面等离子堆焊Ni60B合金层的工艺研究

利用等离子堆焊技术,对动子磁极表面堆焊N i60B合金层开展工艺研究。研究不同堆焊电流对Ni60B合金层组织和性能的影响,以及焊后分别采用水冷、空冷和放入珍珠岩中保温冷却时,对N i60B合金层组织和性能所产生的影响。对焊后样件进行相关试验,结果表明:随着焊接电流的增大,熔深增大,熔覆金属的稀释率增大,表面硬度降低,结合强度增大;从微观金相来看,焊后水冷易导致堆焊层产生裂纹,而焊前预热和焊后缓冷则能有效防止堆焊层产生裂纹。

6082T6铝合金板搅拌摩擦焊接工艺研究

本文主要对3 mm厚6082T6铝合金搅拌摩擦焊接工艺进行研究,研究了轴肩下压量、焊接速度、旋转速度工艺参数对接头组织性能的影响,同时对焊接接头进行了金相、显微硬度、拉伸和弯曲等试验。结果表明3 mm厚度6082T6铝合金板搅拌摩擦焊最优工艺参数为,轴肩下压量0.15 mm、旋转速度1400 r/min、焊接速度1000 mm/min时,接头焊缝强度系数可达0.82。

The arc characteristic of ultrasonic assisted TIG welding

Many applications of ultrasonic-assisted methods were used during metal solidification, but they could not be introduced into weld pool. In this paper, a way of ultrasonic assisted TIG welding is introduced. By directly imposed ultrasonic vibration on welding arc, the vibration interacts with arc plasma and passes to the weld pool. Measurement results show that arc pressure is significantly increased with the ultrasonic vibration and the arc pressure distribution models are changed. Bead-on-plate welding tests on SUS304 confirm that this technology can influence the style of metal melting and increase weld penetration depth.

Microstructures and Plane Energy Spectra of X80 Pipeline Steel Welded Joints by Submerged Arc Automatic Welding

X80 pipeline steel was welded with submerged arc automatic welding, the microstructures, cavity sizes, fusion depths and plane scanning of chemical elements in the welded zone, fusion zone, heat affected zone and base steel were observed with OM（optical microscope） and SEM（scanning electron microscope）, respectively. The experimental results show that there is main acicular ferrite in the base steel and welded zone, the microscopic structure of fusion zone is a blocked bainite, and the heat affected zone is composed of multilateral ferrite and pearlite. M-A unit of the welded zone is the main factor to strengthen the welded zone, composed of acicular ferrites. The percentage of cavities in the welded joint is less than that in the base steel, which is beneficial to increasing its mechanical performance and corrosion resistance. The fusion depth in the fusion zone and welded zone is 101.13 μm and 115.85 μm, respectively, and the distribution of chemical elements in the welded zone is uniform, no enrichment phenomena.

Study of pores produced in underwater wet welding

This paper deals with the effect of water depth in the range of 10 m to 80 m upon the formation of pores produced during underwater wet welding. The results show that it is easy for the inner pores to occur owing to the particularity of the molten metal solidification that the outer pores begin to appear when the water depth increases to about 60 m, that the porosity increases and pore grows up as the water depth increases, and that pores are all hydrogen-containing ones through the examination of the variation of number of pores with the residual hydrogen and oxygen content in the weld metal.