Abstract
Economic welding of thick steel plates is an emerging challenge for various engineering applications. However, tungsten inert gas (TIG) arc welding, as an economic and widely used method, is not regarded as a suitable tool to weld thick steel plates due to the shallow penetration in a single-pass operation. In this technical progress, the joining of austenitic high manganese steel of 8 mm thickness was successfully performed using nanowire flux activated TIG welding with a full penetration and a narrow bead geometry. Fe2O3 nanowire was used as flux and compared with microscale Fe2O3 flux. Experimental results showed that with nanowire fluxes, the welding yielded the maximum of more than 8 mm thick penetration (full penetration and melt over the plate) with proper operating parameters in a single pass. In sharp contrast, the penetration is only less than 4 mm for a single pass welding without Fe2O3 flux with the similar parameters. Arc voltage—time variation during welding process was analyzed and the angular distortion was measured after welding to understand the activating effect of optimized flux mixture. Compared to welding joint without flux and with microscale Fe2O3 flux, nanoscale Fe2O3 flux has a larger arc voltage and higher energy efficiency, higher joint strength and less angular distortion. The developed joint with nanowire flux qualified the tensile test with tensile strength of 700.7 MPa (82.38% of base material strength) and 34.1% elongation. This work may pave a way for nanotechnology-enabling welding innovation for engineering application.
Highlights
The tungsten inert gas arc welding (TIG welding), known as Gas tungsten arc welding (GTAW), using an arc between a non-consumable tungsten electrode and the metal workpieces to fuse workpieces under a shielding gas is a greatly important welding process.Acting as an effective method, it is extensively applied to weld sheets, tubes, pipes, plates and castings [1,2]
In the TIG welding of stainless steels with argon shielding, full penetration welding is restricted to joints of a maximum thickness of around
Due to the clean and smooth welded surface, relatively lower equipment costs, superior mechanical properties of TIG. Welding, it is worth focusing on the improvements of penetration in a single pass operating during TIG welding
Summary
The tungsten inert gas arc welding (TIG welding), known as Gas tungsten arc welding (GTAW), using an arc between a non-consumable tungsten electrode and the metal workpieces to fuse workpieces under a shielding gas is a greatly important welding process. Friction-stir welding can be a compelling alternative with lower welding temperature, the tremendous equipment requirement and expensive cost limit the use of this technology [22,23,24,25] To overcome these shortcomings, activated flux-tungsten inert gas welding (A-TIG) is introduced as one of the novel variants of the TIG welding process by using the mixture of inorganic material known as flux [26,27,28,29]. When the target steel plate is ferritic, the increase in weld penetration and the decrease in bead width are significant with the use of the activating fluxes Fe2 O3 , ZnO, MnO2 and CrO3 [34,35]; when welding austenitic steel, the results of adding SiO2 , Fe2 O3 and TiO2 as fluxes are more obvious [36,37].
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