Suppressing the Use of Critical Raw Materials in Joining of AISI 304 Stainless Steel Using Activated Tungsten Inert Gas Welding

Sebastian Balos,Ivan Zabunov,Magdalena Szutkowska,Miroslav Dramicanin,Branka Pilic,Saurav Goel,Petar Janjatovic

doi:10.3390/met9111187

Abstract

The aim of this study was to study the influence of TiO2 coating for its efficacy during the activated-tungsten inert gas (TIG) welding and to suppress the use of consumables that are rich in critical raw materials. Post-welding penetration depth, particle size distribution, microstructure, and microhardness of welded samples were assessed. Based on these results, it was found that there is no direct correlation between the weld metal surface area and the coating. The particle size in the coating, although, seemed to have played an important role, e.g., nanoparticles resulted in an increased penetration depth and depth/width (D/W) ratio as opposed to the submicron-sized particles. The most optimal welding condition resulted when a mixture of submicron-sized and nanometric-sized particles were used. It was demonstrated by the Zeta analyser results that the micron particles rub the nanoparticles due to mechanical friction resulting in smaller oxide particle formation in the coating. Finally, the presence of Marangoni convection in TIG and reversed Marangoni convection in the activated TIG (A-TIG) process were proven by means of the microstructure analysis and measurement, which were found to be positively correlated.

Highlights

Tungsten inert gas (TIG), alternatively called gas tungsten arc welding (GTAW), is a well-established welding process that can produce high-quality welds on different materials, including stainless steels and a wide variety of non-ferrous alloys
To address the problem of yield, activated tungsten inert gas (TIG) (A-TIG), which uses a coating or a flux to act as a catalyser during the welding process, was developed
The two types of 100 coatings used during the A-TIG welding were based on TiO2 oxides of 20-nm nanoparticles and 0.31012

Summary

Introduction

Tungsten inert gas (TIG), alternatively called gas tungsten arc welding (GTAW), is a well-established welding process that can produce high-quality welds on different materials, including stainless steels and a wide variety of non-ferrous alloys. As opposed to gas metal arc welding (GMAW), the process suffers from a relatively low yield so the application of TIG is traditionally limited to relatively thin sections in different welding positions [1,2]. To address the problem of yield, activated TIG (A-TIG), which uses a coating or a flux to act as a catalyser during the welding process (catalyzed TIG welding), was developed. The application of coating before TIG welding was proposed for the first time by the Paton Welding Institute of the National Academy of Sciences, Ukraine, back in the 1960s [3]. Coatings are usually fabricated by mixing metallic oxide powders with solvents, most frequently acetone and ethanol [4,5,6,7,8]

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