气体熔池耦合活性TIG焊熔池N元素分布骤冷分析

采用骤冷法处理不锈钢气体熔池耦合活性TIG焊高温熔池金属,通过控制开始冷却时间,在不影响焊缝成形的前提下,保留N元素在高温熔池内的分布状态,并采用俄歇电子能谱(auger electron spectroscopy, AES)分析了不同位置处N元素的分布规律.结果表明,在熄弧前0.6 s开始冷却时,骤冷效果最好.熔池内N元素沿深度方向整体呈现均匀分布,局部存在较大范围波动;熔池前部和后部边缘位置的氮含量略高于中心位置,熔池中部边缘位置的平均氮含量略低于中心位置;熔池后部总的平均氮含量略高于熔池前部,熔池中部总的平均氮含量介于两者之间.     

氮氧元素联合过渡对气体熔池耦合活性TIG焊电弧的影响

针对外层引入氮氧混合气体的气体熔池耦合活性TIG焊电弧,采用Boltzmann作图法分析在不同耦合度下电弧等离子体的温度分布和电弧电压的变化规律,并与传统TIG焊及外层只引入氧气的气体熔池耦合活性TIG焊进行比较. 结果表明,氮氧联合过渡时气体熔池耦合活性TIG焊电弧的中心区域温度和电弧电压均高于传统TIG焊与外层只引入氧气时的气体熔池耦合活性TIG焊的数值;当耦合度由0变为+2时,电弧中心区域温度与电弧电压均略有升高.     

MnCl2引入对粉末熔池耦合活性TIG焊交流电弧的影响

粉末熔池耦合活性TIG焊接法是一种新型高效焊接方法,通过选择对应的活性剂粉末,可实现几乎所有金属的焊接.针对采用MnCl2作为活性剂的交流粉末熔池耦合活性TIG焊电弧,采集等离子体光谱,利用Boltzmann作图法分析了电弧等离子体温度随时间的变化规律,并结合电弧电压变化规律,通过与传统交流TIG电弧对比研究MnCl2对交流电弧的影响.结果表明,对于交流TIG电弧,EN时段的电弧光谱强度高于EP时段,EN时段的电弧电压小于EP时段,EN时段的电弧温度低于EP时段.而由于活性剂MnCl2的引入,交流粉末熔池耦合活性TIG电弧的中心温度与EN时段和EP时段的电弧电压均高于传统交流TIG电弧,焊缝熔深较传统交流TIG焊显著增加.     

铝合金TIG焊熔池正面图像模式识别

将图像处理与模式识别技术用于铝合金TIG焊接过程信息提取过程，根据铝合金熔池图像随机噪声强的特点，采用加权中值滤波，统计灰度边缘检测、统计期望阈值法和投影方法对铝合金熔池图像进行了预处理。探索了将神经网络用于焊接熔池图像处理的方法，采用BP神经网络对二值化熔池图像进行边缘提取，取得了理想的效果。研究了大电流条件下铝合金熔池图像的对称性，通过单面图像，得到了完全的熔池边缘图像。     

双脉冲TIG焊熔池数值分析

建立了双脉冲电流下TIG焊熔池的三维非稳态数学模型,通过选择合适的边界条件和热物性参数,强烈耦合控制方程组对双脉冲TIG焊熔池进行数值分析,得到了周期性变化的焊接熔池温度场、流场等分布情况,熔宽、熔深的尺寸大小在周期内的变化规律.结果表明,在双脉冲电流作用下的熔池尺寸大于在平均电流作用下的尺寸,有效的增大了焊接熔池尺寸;熔池尺寸随电流的变化具有一定的滞后性,且在高能脉冲作用时的滞后性较强;在双脉冲电流作用下的熔池内部具有更大的流速,其搅拌作用更强.     

活性MAG焊电弧特征及熔池流动分析

提出了活性熔化极气体保护焊新方法,可增加焊接熔深,改善难熔焊接结构的熔合不良,获得高质量的焊接接头.对活性熔化极气体保护焊电弧状态和熔池表面形态进行了采集和分析,用钨粒子示踪法进行试验,分析了电弧形态和熔池流动.结果表明,活性熔化极气体保护焊电弧收缩显著,电弧形态更加集中,熔池内部液态金属的流动方向为从熔池周边向中心流动,熔池流动更为有序.对于钢的活性熔化极气体保护焊方法,熔池流动行为改变是增加焊接熔深的主要因素.     

N和O元素引入对GPCA-TIG焊焊缝冲击韧性的影响

通过外层气体引入O和N元素,气体熔池耦合活性TIG焊(gas?pool?coupled?activating?TIG?welding)可以实现深熔深、高质量和连续焊接.?为了研究清楚O和N元素引入对焊缝冲击韧性的影响规律和机理,针对SUS304不锈钢分别测试了外层气体为O2,N2和O2?+?N2时的焊缝低温冲击韧性,并...     

TIG焊熔池在阶跃参数下的数值分析

建立了恒流作用下TIG焊熔池的非稳态三维数学模型,利用FLUENT软件,通过选择合适的边界条件和热物理性能参数,强烈耦合控制方程组得到焊接熔池温度场、流场等的变化规律,针对熔池尺寸及相对于熔池中心等距点的温度,分析了在不同焊接工艺参数阶跃下的变化规律.结果表明,随着焊接大电流向小电流的阶跃,熔池的尺寸及内部的流速都有一定程度的减小,随着电弧电压、焊接速度、工件板厚和板宽的阶跃,其变化都具有一定的滞后性,通过各种调整焊接工艺参数均可以达到调节熔池尺寸的效果.     

脉冲熔化极气体保护焊熔池的视觉传感与实时控制

研究对脉冲熔化极气体保护焊（GMAW）熔池过程采用视觉传感与实时控制方法的可行性问题。由于GMAW过程的熔滴过渡现象的复杂性，尝试模拟焊工通过观察熔池变化等因素来调整焊接参数获取满意的焊缝成形的行为。建立了脉冲GMAW过程熔池视觉传感系统，宏观上将熔滴过渡对熔池特征的影响作为黑箱过程处理，根据脉冲GMAW弧光光谱分布和熔池图像特征提取，实现对脉冲GMAW熔池动态过程的实时检测。采用辨识算法建立焊接动态过程的数学模型，进而设计脉冲GMAW熔宽的PID控制器，实现对脉冲GMAW熔池宽度的实时控制。试验表明，建立的视觉传感系统、图像处理算法以及控制器设计检测与控制熔池变化在一定程度上的能够满足脉冲GMAW焊缝宽度的实时性与精度要求。     

外层氧气引入对GPCA-TIG焊焊缝性能的影响

针对SUS304不锈钢,采用传统TIG焊和GPCA-TIG焊进行工件表面熔焊,对外层气体引入氧气的GPCA-TIG焊和传统TIG焊焊缝的氧含量、显微组织、拉伸性能和低温冲击韧性进行了测定. 结果表明,GPCA-TIG焊焊缝组织主要为奥氏体和铁素体,铁素体形态以骨架状和板条状为主. 外层引入氧气时,焊缝中的氧含量增加,耦合度为+2时焊缝中的氧含量高于耦合度为0时的,焊缝的抗拉强度均略低于母材的. 耦合度为0的GPCA-TIG焊焊缝冲击性能与传统TIG焊的相同,耦合度为+2的焊缝低温冲击韧性有所降低,达到传统TIG焊的85%.     

不锈钢电弧辅助活性TIG焊

针对不锈钢,提出了一种新型活性YIG焊方法--电弧辅助活性TIG焊,即AA-TIG焊(arc assisted activating TIG welding).该焊接方法通过在正常TIG焊前以活性混合气体作为保护气体,采用小电流钨极电弧预熔待焊焊道表面,可使熔深显著增加,焊接效率大大提高,而且具有可全自动化焊接和工艺可重复性好等优点.分别采用O2+Ar,CO2+Ar,空气作为小电流钨极电弧的保护气体进行了单弧AA-TIG焊.与传统TIG焊比较,发现O2+Ar,CO2+Ar和空气都可显著增加熔深,减小熔宽,焊缝表面成形良好.采用CO2+Ar作为活性混合保护气体进行双弧AA-TIG焊,焊缝成形良好,熔深显著增加.熔深随着焊枪间距减小而增大.     

The element transfer behavior of gas pool coupled activating TIG welding

This paper deals with a novel dual shield TIG welding method named gas pool coupled activating TIG( GPCA-TIG)welding. The welding method divides the shielding gas into two layers. Inert gas such as Ar is adopted as the inner layer gas to protect the tungsten electrode and the molten pool metal. Pure O_2,N_2 or mixture of them are used as the outer layer gas to increase the weld penetration and improve the low temperature toughness of weld metal. Through analyzing the interaction between outer gas and arc and the distributions and existing forms of oxygen and nitrogen elements,the transfer behaviors of nitrogen and oxygen from arc to pool were investigated. The results show that,the interaction between the outer gas and arc plasma makes the arc slightly constrict. The incoming oxygen enriches on the molten pool surface and exists in the form of iron oxide,chromium oxide,manganese oxide and silicon oxygen compounds. The incoming nitrogen evenly distributes in the molten pool and exists in the form of nitrogen atom.     

双层气流保护TIG焊接方法

介绍了一种双层气流保护TIG焊接方法,它适用于TIG焊接过程,解决现有普通TIG焊接熔池深度较浅和混合气体保护下钨极易氧化烧损的问题.该焊接方法将传统单一气体通道的TIG焊枪改造设计为双层气体通道,内层气体为纯惰性气体,保护电极,外层为惰性气体和活性气体的混合气体,向熔池过渡活性组元,改变熔池传热对流模式,增加熔池深度.结果表明,双层气流保护TIG焊接方法可使TIG焊熔池深宽比较普通弧焊深宽比增加2～3倍,同时避免了钨极氧化烧损,延长使用寿命.     

Development of maintenance technology with underwater TIG welding for spent fuel storage pool

The core technology of an underwater TIG welding process has been developed and a welding equipment system has been manufactured for application to the maintenance of the spent fuel storage pool of Rokkasho reprocessing plant. Basic experiments for understanding the conditions of the dry area and the range of welding conditions was performed, and mock examination for simulation of the real environment by using the developed welding equipment was also carried out to judge the applicability of the system.

For the purpose of selecting a water removing method for different spatial conditions of the parts to be maintained underwater, two kinds of welding equipment systems of Chamber type and Partition type were developed and manufactured.

On the basis of fundamental experiments, the conditions of dry area formation and welding parameter range for high-reliability weld are discussed. Thus the proper condition of this process was able to be established.

With the welding equipment systems of the Chamber type and Partition type, the practical use examination of underwater TIG welding process was executed by mock examination for simulating the real environment. As a result, it was confirmed that the underwater TIG welding could obtain the same reliability as a usual in-air TIG welding, and the operation and the control at remote distance were also possible. And the reliability of the patch-plate fillet weld could be evaluated by remote inspection with the expansion visual test.     

激光辅助活性焊接法

提出了激光辅助活性焊接的方法,研究了焊接参数对激光熔化处理后TIG焊接熔深、熔宽的影响.首先,使用极小功率激光在氧气保护下熔化焊件表面,使焊缝表面的氧含量增加.然后使用普通的TIG焊接,覆盖激光焊缝,达到增加熔深的目的.利用此方法,不使用活性剂就可以使TIG焊焊接熔深增加约2倍,与A-TIG焊相比没有表面熔渣,表面成形较好.小功率激光处理后焊缝中O元素含量增加,熔池表面张力温度系数由负变正,导致激光辅助活性焊熔深增加.

Abstract：

On the bases of the study for the mechanism of the increasing of A-TIG welding penetration, a new method of activating TIG welding, the laser aided activating TIG welding was proposed. At first, the surface of weld was melt by the mini power laser protected by oxygen. As a result, the oxygen content increases in the weld pool surface. Then the conventional TIG welding was used to cover the weld. The oxygen could change the direction of fluid flow in molten pool, which leads to the weld beads with narrower width and deeper penetration. Without the activating flux, the penetration can be increased by 2 times. There is no slag in the surface of weld and the appearance is good. The oxygen can change the temperature dependence of surface tension gradient from a negative value to a positive value; and cause the significant changes in the weld penetration. Fluid flow could be inward along the surface of the weld pool toward the center and then down. This fluid flow pattem transfers heat to the weld root and produces a relatively deep and narrow weld efficiently. This change is the main cause to increase the penetration.     

铝合金气体输送活性钨极氩弧焊方法

针对铝合金,提出了一种气体输送活性钨极氩弧焊,即GTFA-TIG焊(gas transfer flux activating TIG welding).该方法改变了活性元素的引入方式,通过自动送粉装置将活性剂输送到保护气体中,由保护气体将其引入电弧-熔池系统进行施焊,使得电弧收缩,熔池金属流态改变,熔深增加,同时省却了涂覆活性剂工序,实现了焊接过程自动化.进行了普通交流TIG焊和8种单组元活性剂的GTFA-TIG表面熔焊,分析了不同活性剂对焊缝成形、拉伸性能以及缺陷的影响.结果表明,大多数卤化物和氧化物活性剂都能使熔深增加到传统TIG焊的2.5~3倍以上,单质碲增加熔深效果较差.采用V₂O₅的焊缝抗拉强度接近母材金属,而采用MnCl₂和AlF₃的焊缝有一定程度降低.焊缝X射线探伤结果表明,采用V₂O₅,MnCl₂和AlF₃的焊缝评片结果均为Ⅰ级,而采用碲的焊缝为Ⅲ级.