The fatigue crack propagation behavior is a key issue for the service of engineering materials. The effect of electropulsing treatment (EPT) on the growth of fatigue crack in a high‐strength steel (AISI 4340 steel) is investigated. It is shown that the crack propagation rate could be significantly declined via high‐density EPT. The crack features of fracture surface are examined using laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM). The crack deviation, local crack‐healing and bridging phenomenon are proposed to be beneficial to lower the crack propagation rate, which should be brought out by the current detour, selective Joule heating, compressive stress, and electrical breakdown phenomenon. All these EPT effects exhibit significant contributions to the improvement of fatigue properties in the widely used high‐strength steel.

Considering the consumption of time and energy for the traditional heat treatment process, a new heat treatment method with high speed and low energy consumption has always been the direction of researchers. The microstructure and mechanical properties of engineering 316L stainless steel were measured under electropulsing treatment within 400 ns and annealing treatment for 2 h. Compared with the original cold-rolled state, it was found that the yield strength after 3.8 × 103 A/mm2 electropulsing treatment was reduced by 26.2% and that after 800 °C heat treatment was reduced by 27.7%. The nucleation after electropulsing treatment is mainly concentrated at one end of the lamellar grain and finally grows into the square or rhombic grain with an average grain size of 1.5 µm. After annealing, the nucleation is mainly concentrated at the grain boundaries of the lamellae and finally grows into equiaxed grains with an average grain size of 1.8 µm. Under the action of electronic wind, the recrystallization nucleation after electropulsing is mainly dominated by the mechanism of subgrain nucleation and growth. However, under the action of a uniform thermal field, the recrystallization nucleation after annealing is mainly based on the grain boundary bow-out mechanism.