Abstract

The purpose of this study was to investigate the difference between tungsten inert gas (TIG) welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO2 and Al2O3 were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results show that the use of SiO2 leads to a satisfactory surface appearance compared to that of the TIG weld made with Al2O3. The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type. Compared with microparticle SiO2, the TIG welding with nanoparticle SiO2 has the potential benefits of high joint penetration and less angular distortion in the resulting weldment. The TIG welding with nanoparticle Al2O3 does not result in a significant increase in the penetration or reduction of distortion. The TIG welding with microparticle or nanoparticle SiO2 uses a heat source with higher power density, resulting in a higher ferrite content and hardness of the stainless steel weld metal. In contrast, microparticle or nanoparticle Al2O3 results in no significant difference in metallurgical properties compared to that of the C-TIG weld metal. Compared with oxide particle size, the thermal stability of the oxide plays a significant role in enhancing the joint penetration capability of the weld, for the UNS S31603 stainless steel TIG welds made with activated oxides.

Highlights

  • Tungsten inert gas (TIG) welding can produce a high-quality weld, its application is usually limited to thin plates welded by a single-pass procedure, and the process suffers from relatively low productivity

  • The purpose of this study was to demonstrate that the surface appearance, geometric shape, angular distortion and metallurgical properties of the UNS S31603 stainless steel A-tungsten inert gas (TIG) welds greatly depend on the thermal stability and particle size of the activated oxides

  • The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type

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Summary

Introduction

Tungsten inert gas (TIG) welding can produce a high-quality weld, its application is usually limited to thin plates welded by a single-pass procedure, and the process suffers from relatively low productivity. One approach to increase the productivity of TIG welding is to add quantities of minor surface-active elements to the molten metal This can be accomplished by a number of technologies, including coated activated fluxes (such as oxides or sulfides) on the steel plate surface [1,2,3,4,5,6,7,8,9,10] or added active gases (such as oxygen, carbon dioxide or sulfur dioxide) to an inert gas [11,12,13]. The heat-to-heat variations in weld depth for some stainless steels or nickel-based alloys can be eliminated by using an activated flux This method of improving both the amount and consistency of the joint penetration in the TIG weld may provide a significant economic benefit to the manufacturing industry. Three kinds of polar solvent were used to investigate the coverability, spreadability and volatility of the flux-coated layer

Experimental Details
Results and Discussion
Evaluation of Activated Oxides Mixed with Polar Solvents
Conclusions
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