<p>To enhance the bending resistance of bellows, an environmentally friendly electric pulse heat treatment (EPHT) method was used. The strengthening mechanism was systematically studied by microstructure characterization, finite element simulation and bending test. The results showed that during EPHT process, the cross-sectional area of the trough was small, so that the current density was large, which made the temperature of the trough significantly higher than those of other regions. The temperature difference between the peak and the&#xa0;trough was most influenced by frequency. Empirical formulas were derived to predict the temperature and current density of the trough under varying parameters. The dislocation elimination and grain growth of the trough achieved the optimal balance at 800&#xa0;°C and 7 A/mm², obtaining the best bending resistance. Bellows prepared by general heat treatment process (GHTP) had coarse grains and local high dislocation density areas. In contrast, the grains of EPHT bellows were fine, the dislocations were eliminated completely and uniformly, and the crack propagation path was more tortuous. Compared with GHTP, EPHT significantly reduced the dislocation density and eliminated oxide inclusions. This microstructural optimization altered the crack propagation behavior from simultaneous bidirectional growth (initiating from both high-strain surfaces and wall center) to unidirectional propagation (surface to center) of GHTP, thereby greatly reducing the crack propagation rate. Notably, the fracture mechanism changed from quasi-cleavage to ductile fracture. Compared with GHTP, the number of bending cycles of EPHT bellows increased by about 200% before fracture.</p>