Bingxing Wang

Thin metallic bipolar plates with fine flow channels are prone to nonuniform filling and localized thinning, particularly when high-strength Inconel 718 is formed into complex microchannels. To clarify the spatial deformation characteristics under superplastic conditions, a reduced internal-state-variable-based viscoplastic model was implemented in Abaqus and validated against experimental channel geometry and thickness distributions, with a mean absolute percentage error of 3.63%. The effects of forming temperature, deformation time and initial sheet thickness were evaluated through single-factor simulations and an L9 (3³) orthogonal analysis. Straight-channel nonuniformity was governed mainly by edge-controlled material feeding: increasing temperature or deformation time reduced forming resistance and edge draw-in and improved channel-depth uniformity, but promoted local grain growth. Corner-channel thinning was controlled primarily by geometry-induced strain localization. Longer deformation time effectively reduced maximum thinning, whereas temperature mainly lowered local stress and had limited influence on thickness loss. Increasing sheet thickness reduced corner thinning up to about 0.14 mm, beyond which the benefit became limited. Orthogonal analysis showed that deformation time dominated global and straight-channel responses, while sheet thickness dominated local corner thinning. The results reveal two governing regimes-rate-dependent flow with edge feeding for straight channels, and geometric localization with thickness reserve for corner channels, providing a mechanistic basis for process design of Inconel 718 bipolar plates.

High-flexibility copper foils are critical for reliable flexible interconnects and displays. In this work, commercial-purity copper belts were processed by triple-layer stacked cold rolling to ultrathin foils, producing distinct surface- and layer-dependent deformation structures in the bright, matte, and central-interface layers; subsequent annealing at 600 °C then promoted orientation-selective recrystallization. Under the present conditions, the center-interface layer of the triple-rolled foil achieved the highest flexural-fatigue life (≈8.0 × 10⁴ cycles) within a window of cube ≈ 30–45% and grain size ≈ 40–60 μm. In this regime, grain-size control stabilizes intergranular slip compatibility, reduces elastic–plastic mismatch, and mitigates strain localization during cyclic bending. Even without aggressive cube enrichment, high flexural fatigue resistance can likewise be achieved through deliberate control of grain size. These findings establish a clear processing–microstructure–property linkage and indicate that layer-dependent control of texture and grain size can enhance flexural-fatigue performance in triple-layer stacked-rolled copper foils for flexible electronics.

The oxide metallurgy is used in the fabrication of X80 pipeline steel. The mechanical properties of X80 steel at different tempering temperatures are studied by offline heat treatment process. The hydrogen‐induced cracking (HIC) susceptibility of X80 steel with optimal mechanical properties is studied. The results show that the optimal combinations of mechanical properties are obtained for the X80 pipeline steel under the heat treatment conditions of water quenched at 900 °C and tempered at 630 °C. The yield strength of the X80 steel is 569 MPa and the impact energy is higher than 300 J at −40 °C. After deoxidation by Ti and Zr, the average size of inclusions in X80 steel is 0.23 μm. Among them, the typical spherical composite inclusions are TiO_X–Al₂O₃–ZrO₂–MnS, combined with the fine (Nb, V, Ti)C and the formation of Cu₂S and Cr₂O₃ protective layers. X80 steel has excellent HIC resistance.