A comparative analysis of the impact of fillet weld geometry on residual stress distribution in nickel-based superalloy

This paper investigates the influence of various fillet weld geometries on the dispersion of residual stress within an austenitic nickel-based superalloy. The weld fabrication has been implemented using the gas tungsten arc welding (GTAW) process. The distribution of residual stress induced by welding profoundly affects the operational longevity of welded components. Despite the minuscule nature of cracks, the accumulation of elevated surface residual stress intensifies crack propagation, thereby constraining the service life of the welded component. A Prior understanding of surface stress distribution can aid in designing a component with an adequate safety margin, consequently diminishing the likelihood of failure. Empirical examinations were conducted on the concave fillet weld profile employing the blind hole drilling method (BHD), corroborated by computationally derived outcomes. Experimental measurements were utilized to affirm the reliability of the computational methodology. Following the concave weld profile geometry, two alternative weld profiles, namely convex and triangular fillet geometries, have been suggested for examination. A coupled thermo-mechanical computational approach, leveraging ABAQUS FEA software, was devised to scrutinize residual stress distribution within the welded joint. A three-dimensional finite element model specific to Alloy 617 was constructed to anticipate the welding stress field across three distinct fillet-welded joints. The numerical study used a mixed hardening model, which combines isotropic and kinematic properties. A concave weld exhibits a notable high tensile hoop stress reaching 160 MPa, contrasting with a convex weld where the maximum tensile hoop stress is observed to be 70 MPa. Analyzing a concave fillet weld reveals that the amplitude of both hoop and axial residual stresses is distributed across 80% of the weld. On the other hand, in a convex fillet weld profile, these values are significantly diminished, measuring below 40%.