Welding Journal Research Supplement

Abstract

This paper presents a modified Goldak heat source (GHS) model applied to duplex stainless steel (DSS) wall-of-weld (WoW) and AA5356 aluminum in wire arc additive manufacturing (WAAM) using gas metal arc welding. Although prior modifications to the GHS exist, none have addressed the actual arc origin following arc initiation. Consequently, maintaining realistic parameter ranges in the standard GHS often results in artificially high temperatures, inconsistent interlayer boundaries, or large relative errors compared to experimental data. In this study, an arc origin offset (as a new Goldak parameter, Z0 ) is introduced in the double ellipsoidal heat source equations, reflecting the actual location of peak heat input. As a result, Z0 improves the prediction of solid-liquid phase transitions of the melt pool cross sectional geometry validated by the macrographs. A thermal study optimizing this parameter, alongside a parametric study of this Modified GHS (MGHS), is first implemented on DSS-WoW and subsequently on the AA5356-WoW. The standard GHS and the MGHS are compared in each case and validated against experimental results and DSS macrographs. The results demonstrate how Z0 enhances standard GHS and, more importantly, adjusts it to WAAM beyond a single weld bead. Additionally, an experiment conducted by the authors on an AA1100 Tube-to Weld using a moving pyrometer (MIKRON-ME-PI 140) accurately confirmed the MGHS model. To estimate the Z0 value in a more generalized way, a novel dimensionless number was developed to empirically relate Z0 to five alloys and process parameters. This enables researchers and engineers to select the desired Z0 value.