Gas protection is very important in arc welding processes and several factors influence its effectiveness. This paper provides a discussion of the applicability of the Schlieren technique to arc welding processes. Tests were performed with different types of shielding gas and with GMAW and GTAW torches, in order to highlight differences associated with the various conditions. The results obtained in conjunction with a review of results reported in the literature allowed an evaluation of the limitations associated with the use of the Schlieren technique in the arc welding processes. The most important limitation is that the visualization is inherently difficult when using pure Ar gas, meaning that in most situations it is not possible to adequately visualize the flow interface with atmospheric air, which is the main region of interest in this type of analysis. However, visualization is possible in regions where pure Ar is heated, or when mixtures with other gases are used. In addition, the results obtained with different sources of light were compared and the test was performed by filming the arc welding or with the gas flowing through the torch without the arc. The differences observed in the results obtained are discussed herein.

气体保护在电弧焊过程中非常重要，几个因素会影响其有效性。本文讨论了Schlieren技术在电弧焊工艺中的适用性。为了突出与各种条件相关的差异，使用了不同类型的保护气体以及GMAW和GTAW焊炬进行了测试。结合文献中报道的结果进行回顾所获得的结果，可以评估与在电弧焊过程中使用Schlieren技术相关的局限性。最重要的限制是，在使用纯Ar气体时，可视化本来就很困难，这意味着在大多数情况下，无法充分可视化大气中的流动界面，这是此类分析中的主要关注区域。但是，在纯Ar加热的区域或使用与其他气体的混合物时，可以进行可视化。另外，比较了用不同光源获得的结果，并通过成膜电弧焊或在没有电弧的情况下使气体流过焊枪进行了测试。本文讨论了在获得的结果中观察到的差异。