<p>This article presents a combined digital image correlation and finite element approach for heat-affected zone (HAZ) identification. Weld filets were obtained from line pipe steel. A combination of metallographic, mechanical, and scanning electron microscopy (SEM) analyses was used to estimate the heat-affected zone widths. Subsequently, digital image correlation (DIC) during tensile testing allowed for the simultaneous determination of the constitutive behavior of sub-regions. For the ductile region, experimental stress–strain data were fitted using various phenomenological constitutive models. The most suitable model was then extrapolated to determine the ultimate tensile strength based on the Considère criterion. By varying the heat-affected widths, the resulting constitutive model was implemented in a finite element code for analysis and validation against experimental data. Experimental results indicate that the hardness and the ductility of the heat-affected zone were increased compared to those of the base metal. Numerical simulation results revealed a good correlation with those of experimental data up to the initiation of diffuse necking for the previously estimated heat-affected zone width through both the scanning electron microscopy observations and microhardness profile measurements. Based on these findings, the proposed methodology for determining heat-affected zone constitutive behavior has demonstrated its effectiveness and may serve as a valuable welding qualification procedure, particularly when compliance with specified yield strength ratio standards is required.</p>