A Comparative study of pulsed and non-pulsed current on aspect ratio of weld bead and microstructure characteristics of AISI 304L stainless steel

Abstract

The aim of this work is to investigate the influence of the welding process parameters on the weld bead geometry, microstructure characteristics, and mechanical properties of weldments curried out using TIG welding with pulsed/non pulsed current processes. The cooling state was introduces as an input parameter to investigate the main effects on the structure morphology and thereby the mechanical property. In this work the selected pulse frequency levels were 5-500 Hz in order to show the effect of low and high frequencies on the weldment characteristics of AISI 304L plates using filler metal of ER 308LSi. In this work, three levels four factors Taguchi L9 orthogonal array was used to analyze the aspect ratio of the welded specimens. Taguchi analysis was performed for the main effects plot to optimize the process parameters. Furthermore, the microstructure evolution has been investigated. Thus key findings of this work clarified that the pulse frequency has significant effect on the breaking of the dendrite arms during welding process and so strongly affects on the tensile strength. The cooling state also affects on the microstructure texture and thereby, the mechanical properties. The most important factor affects the bead geometry and aspect ratio is the travel speed.

Keywords: TIG welding, microstructure, mechanical properties, pulse frequency, austenitic stainless steel.