Low-angle grain boundaries (LAGBs) accommodate residual stress through the rearrangement and accumulation of dislocations during cold rolling. This study presents an electron wind force-based annealing approach to recover cold-rolling induced residual stress in FeCrAl alloy below 100 °C in 1 min. This is significantly lower than conventional thermal annealing, which typically requires temperatures around 750 °C for about 1.5 h. A key feature of our approach is the athermal electron wind force effect, which promotes dislocation movement and stress relief at significantly lower temperatures. The electron backscattered diffraction (EBSD) analysis reveals that the concentration of low-angle grain boundaries (LAGBs) is reduced from 82.4% in the cold-rolled state to a mere 47.5% following electropulsing. This level of defect recovery even surpasses the pristine material’s initial state, which exhibited 54.8% LAGBs. This reduction in LAGB concentration was complemented by kernel average misorientation (KAM) maps and X-ray diffraction (XRD) Full Width at Half Maximum (FWHM) measurements, which further validated the microstructural enhancements. Nanoindentation tests revealed a slight increase in hardness despite the reduction in dislocation density, suggesting a balance between grain boundary refinement and dislocation dynamics. This proposed low-temperature technique, driven by athermal electron wind forces, presents a promising avenue for residual stress mitigation while minimizing undesirable thermal effects, paving the way for advancements in various material processing applications.

Traditional approaches to control the microstructure of materials, such as annealing, require high temperature treatment for long periods of time. In this study, we present a room temperature microstructure manipulation method by using the mechanical momentum of electrical current pulses. In particular, a short burst of high-density current pulses with low duty cycle is applied to an annealed FeCrAl alloy, and the corresponding response of microstructure is captured by using Electron Backscattered Diffraction (EBSD) analysis. We show evidence of controllable changes in grain orientation at specimen temperature around 28 °C. To demonstrate such microstructural control, we apply the current pulses in two perpendicular directions and observe the corresponding grain rotation. Up to 18° of grain rotation was observed, which could be reversed by varying the electropulsing direction. Detailed analysis at the grain level reveals that electropulsing in a specific direction induces clockwise rotation from their pristine state, while subsequent cross-perpendicular electropulsing results in an anticlockwise rotation. In addition, our proposed room temperature processing yields notable grain refinement, while the average misorientation and density of low-angle grain boundaries (LAGBs) remain unaltered. The findings of this study highlight the potentials of ‘convective diffusion’ in electrical current based materials processing science towards microstructural control at room temperature.

This study investigates the effectiveness of combined thermal and athermal stimuli in mitigating the extremely high-density nature of dislocation networks in the form of low-angle grain boundaries in FeCrAl alloy. Electron wind force, generated from very low duty cycle and high current density pulses, was used as the athermal stimulus. The electron wind force stimulus alone was unable to remove the residual stress (80% low-angle grain boundaries) due to cold rolling to 25% thickness reduction. When the duty cycle was increased to allow average temperature of 100 °C, the specimen could be effectively annealed in 1 min at a current density of 3300 A/mm². In comparison, conventional thermal annealing requires at least 750 °C and 1.5 h. For specimens with 50% thickness reduction (85% low-angle grain boundaries), the electron wind force was again unable to anneal the defects even at 3300 A/mm² current density and average temperature of 100 °C. Intriguingly, allowing average concurrent temperature of 200 °C eliminated almost all the low-angle grain boundaries at a current density of 700 A/mm², even lower than that required for the 25% thickness reduced specimens. Comprehensive electron and X-ray diffraction evidence show that alloys with extremely high defect density can be effectively annealed in less than a minute at approximately 200 °C, offering a substantial improvement over conventional high-temperature annealing.