Activated flux-tungsten inert gas welding of high-manganese steel thick plates with Fe2O3 nanowire flux for Improved welding and mechanical properties

Tungsten inert gas arc welding is an economic and widely used method for various metal welding. However, it is still challenging to apply for a thick steel plate because of the shallow penetration in a single pass operation. In this work, the joining of austenitic high manganese steel of 8 mm thickness was performed using activated flux - tungsten insert gas arc welding (A-TIG) process with aim to develop an increased penetration and a narrower bead geometry. Microscale Fe₂O₃ was used as flux and nanoscale Fe₂O₃ flux was also synthesized as comparison. Experimental results showed that with both micro and nanoscale fluxes, the welding gave a significantly increased penetration with a single pass. 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. Comparing weldments without flux and with microscale Fe₂O₃ flux, nanoscale Fe₂O₃ flux has the larger arc voltage, higher joint strength and less angular distortion. The developed joint with nanoscale flux qualified the tensile test with tensile strength of 700.7 MPa (82.38% of base material strength) and 34.1% elongation. Furthermore, for convenience, spray gun was used for scribbling the flux onto the metal, and obtained a better result than brushing. This work may pave a way for nanotechnology-enabling welding innovation for engineering application.