Effect of ambient atmosphere on penetration geometry in single laser and laser-arc hybrid welding. Welding phenomena in hybrid welding using YAG laser and TIG arc (second report)
Effect of ambient atmosphere on penetration geometry in single laser and laser-arc hybrid welding. Welding phenomena in hybrid welding using YAG laser and TIG arc (second report)
复制标题
环境气氛对单激光和激光电弧复合焊接熔深几何形状的影响。
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
S. Katayama
中科院分区：
文献类型：
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作者：
Y. Naito;M. Mizutani;S. Katayama
激光-电弧复合焊接具有熔深大、气孔率低、生产效率高等优点，近年来受到广泛关注。对于第一份报告，进行了基本实验，以确定一系列参数的影响，如激光功率，电弧电流和激光和电弧之间的距离，在使用YAG激光器和TIG电弧作为混合电源的渗透。获得了前所未有的结果，例如：当激光和电弧之间的距离变化时，焊接区的几何形状和熔深显著变化;特别是，当用领先的YAG激光束进行焊接时，熔深变得与仅使用激光的焊接相比相同或更小。此外，获得了在以前的报告中未观察到的结果，例如：在仅用激光和用100 A的混合焊接进行的焊接中，上部熔合区宽度的狭窄和细长的几何形状，以及在用200 A的混合焊接进行的焊接中，钉头区域熔深显著增加。因此，需要进行与上次报告所述不同的实验，以阐明原因。近年来，研究表明，钢在电弧焊时，表面活性元素如硫、氧等对表面张力起作用，影响熔深特性，另外，近年来的数值计算结果表明，表面张力驱动的对流效应也是不可忽视的。此外，Lu等人报道了由于Ar保护气体中的氧含量而导致的不同渗透轮廓的现象，并认为原因是表面张力驱动的对流的影响。即使在电弧电极和激光束相结合的混合焊接中，保护气体供给方法和保护状态也会因配置和环境气氛而变化;特别是，氧气被认为会影响熔深和熔合区轮廓;然而，迄今为止还没有具体和系统地研究气氛对熔深特性影响的实例。因此，在本报告中，如前所述，主要在空气中对具有低S含量的SUS 304不锈钢进行使用YAG激光和TIG电弧的复合焊接，此外，在纯氩气气氛和在Ar保护气体中的氧比例在密封样品和处理点环境的腔室内变化的气氛中进行复合焊接，研究了焊接条件的影响，特别是大气中的氧气对熔深及其几何形状的影响。此外，在没有空气影响的纯Ar气体气氛下，对具有高S含量的不锈钢和具有低S含量的SUS 304不锈钢进行激光焊接和混合焊接，其中仅表面被氧化;将所获得的焊接几何形状与通过在其中混合有氧气的气氛下进行焊接所获得的焊接几何形状进行比较，定义了熔合区的几何形状和表面张力的最终作用。
Laser-arc hybrid welding has received much attention in recent years from the aspects of increased penetration depth and gap tolerance, reduced porosity and high productivity. For the first report, fundamental experiments were conducted to define the effects of a range of parameters, such as laser power, arc current and distance between the laser and the arc upon penetration using a YAG laser and a TIG arc as a hybrid power source. Unprecedented results were obtained such as: when the distance between the laser and the arc was varied, the weld zone geometry and penetration depth markedly changed; in particular, when welding was carried out with a leading YAG laser beam, the penetration depth became either the same or less compared with that obtained by welding using only the laser. Furthermore, results, not observed in the previous reports, were obtained such as: a narrow and elongated geometry of the upper fusion zone width in welds made only with the laser and with hybrid welding at 100 A and a substantially increased nail head zone penetration in welds made with hybrid welding at 200 A. Consequently experiments different from those described in the previous report are required in order to explicate the causes. Hitherto it has been shown that when steel is arc welded, surface active elements such as sulphur and oxygen act upon surface tension and affect the penetration characteristics and additionally, it has been reported in recent years that the results of numerical calculation indicate the effects of surface tension driven convection are not insignificant. Furthermore, Lu and others reported a phenomena of varied penetration profile due to the oxygen content in the Ar shielding gas and suggested the cause to be the effects of surface tension driven convection. Even with hybrid welding, where an arc electrode and a laser beam are combined, the shielding gas feeding methods and the state of shielding vary due to configuration and ambient atmosphere; in particular, oxygen is thought to affect the penetration depth and the fusion zone profile; however, there are so far no examples of concrete and systematic investigations into the effects of atmosphere upon penetration characteristics. Accordingly, in this report, hybrid welding using YAG laser and TIG arc was performed in air, as before, mainly on SUS 304 stainless steel which has a low S content; in addition, hybrid welding was carried out both in pure argon atmosphere and in the atmosphere where the proportion of the oxygen within the Ar shielding gas was varied within the chamber where the specimens and the processing point environment were sealed; the effects of the welding conditions were studied, particularly oxygen within the atmosphere upon penetration and its geometry. Furthermore, laser welding and hybrid welding were carried out on stainless steel with a high S content and SUS 304 stainless steel with a low S content and where the surface only had been oxidised, under a pure Ar gas atmosphere without the influence of the air; the weld geometry obtained was compared with that made by welding under an atmosphere where oxygen was mixed and thus the effects of oxygen within the atmosphere upon the fusion zone geometry and the resulting action of the surface tension were defined.