Abstract
Advanced oxide dispersion strengthened (ODS) alloys are leading candidates for structural components in advanced reactors with demonstrated corrosion resistance, dimensional stability upon irradiation, and favorable mechanical properties at high temperatures. Unfortunately, most established joining processes (arc welding and friction stir welding) result in significant alteration of the microstructures, including agglomeration of the nanoscale features that make these alloys competitive and irradiation resistant. In this study, ODS alloy MA956 is laser-welded in a commercial environment followed by irradiation with Fe2+ ions to 25 displacements per atom at 400°C, and the resulting microstructure and mechanical properties are characterized. The weld was unable to fully penetrate the workpieces, and the fusion zone exhibits significant softening (∼1.50 GPa reduction in nanohardness). Dispersoid morphology coarsened during the welding process leading to a slight decrease in sink strength within the weld. Irradiation-induced hardening was more dramatic within the laser weld region largely attributed to a 25% larger size of dislocation loops generated in the laser weld as compared to the bulk material.