Welding is a widely used process that requires continuous developments to meet new application demands of mechanical projects under severe conditions. The homogeneity of metallurgical and mechanical properties in welded joints is the key factor for any welding process. The applications of external magnetic fields, mechanical vibration, and ultrasound are the fundamental steps to achieve success in improving these properties. The present work aimed at determining suitable processing conditions to achieve the desired balance between metallurgical and mechanical properties of 304L steel in TIG (Tungsten Inert Gas) welding under the application of an external magnetic field. The microstructural characteristics of the weld bead were analyzed by optical microscopy (OM) and scanning electron microscopy (SEM). In order to evaluate the mechanical properties of the welded specimen, its Vickers microhardness map and Charpy impact energy at −20 °C were obtained. In addition, corrosion tests were carried out in the saline medium to compare the corrosion resistance of the joint with that of the base metal and that without the magnetic field. It was found that the external magnetic field decreased the percentage of delta ferrite, improved the filling of the weld pool with the weld metal, and decreased the primary and secondary dendritic spacings. The Vickers microhardness value under the magnetic field was found to be lower than that without the magnetic field, and the Charpy test showed no significant variation in energy absorption. Moreover, the welded joint produced under the external magnetic field manifested less resistance to corrosion.

中文翻译：

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TIG焊接中外部磁场对熔合区组织和力学性能的影响

焊接是一种广泛使用的过程，需要不断发展以满足苛刻条件下机械项目的新应用需求。焊接接头的冶金和机械性能的均匀性是任何焊接工艺的关键因素。外部磁场，机械振动和超声波的应用是成功改善这些特性的基本步骤。本工作旨在确定合适的加工条件，以在外部磁场作用下在TIG（钨极惰性气体）焊接中实现304L钢的冶金和机械性能之间的所需平衡。通过光学显微镜（OM）和扫描电子显微镜（SEM）分析了焊缝的显微组织特征。为了评估焊接试样的机械性能，获得了其维氏显微硬度图和-20°C下的夏比冲击能。另外，在盐介质中进行了腐蚀试验，以比较接头与母材和无磁场时的耐腐蚀性。已经发现，外部磁场降低了δ铁素体的百分比，改善了焊缝金属对焊缝的填充，并减小了一次和二次枝晶间距。发现在磁场下的维氏显微硬度值低于没有磁场的情况下的维氏硬度，并且夏比试验表明能量吸收没有显着变化。此外，在外部磁场下产生的焊接接头表现出较小的耐腐蚀性。