Extra “Knob” to Microstructural Engineering for Metals and Alloys via Transient Athermal Electropulsing Treatment

Unconventional microstructural engineering has enabled superior mechanical properties in alloys, yet most methods rely on intense thermal or mechanical inputs, limiting bulk‐scale applicability. Here, we demonstrate an athermal electropulsing treatment (EPT) as a novel field‐assisted strategy to refine the microstructure of high‐carbon M50 bearing steel used in aeroengines, without bulk heating. Under near‐isothermal conditions, high‐density current pulses are applied, inducing significant structural changes. Above a threshold current density of 140 A mm −2 , EPT promotes grain refinement and secondary carbide precipitation; below this level, only recovery or grain coarsening occurs. The optimized EPT process achieves uniform nanocarbide dispersion and fine grains, substantially enhancing wear resistance. Mechanistic analysis reveals that rapid electronic energy deposition leads to nonequilibrium effects, including electron wind forces and localized thermal spikes, which drive recrystallization and solute redistribution on the millisecond timescale. Unlike conventional heat treatment or severe plastic deformation, this approach avoids bulk heating, large plastic strains, and residual stress. These findings establish EPT as a viable non‐thermal pathway for activating phase transformations and defect dynamics, enabling new alloy processing routes beyond the reach of traditional methods.