The influence of heat input in orbital TIG welding on various diameters and thicknesses of low-carbon steel tube

Abstract

Partial joint penetration (PJP) welding is widely applied in structural, mechanical, and piping systems where full penetration is not required, offering benefits in cost, time efficiency, and reduced heat input. The main goal was to evaluate the effects of Heat Input on the weld geometry and ultimate tensile strength of low-carbon steel tubes. Therefore, the welds were carried out using Orbital TIG Welding, designed to achieve partial joint penetration (PJP). The number of experiments and the welding parameter matrix were created using the Taguchi method (L9) for various diameters of Ø48×3.2mm, Ø60×2.6mm, and Ø89×2.9mm. The results indicated that, under the same Heat Input levels, variations in tube thickness had a greater impact on weld profile and ultimate tensile strength than changes in diameter. Furthermore, the ANOVA analysis ranks the influence of welding factors on tensile strength. This study proposes an optimal set of welding parameters and predicts the corresponding tensile strength for each pipe diameter, thereby providing valuable insights for improving the reliability and performance of welded joints.