Key control points of vanadium foil cold rolling and annealing process

1, vanadium foil cold rolling process precautions
Rolling parameter control
Before cold rolling, it is necessary to ensure that the surface of vanadium foil has no defects such as oxidized iron sheet and scratches, so as to avoid cracks or delamination. The thickness is gradually reduced by multi-pass rolling, and the thickness uniformity is ensured by dynamically adjusting roll gap spacing and rolling tension (such as increasing roll bending force to eliminate bilateral wave shape). Thin size vanadium foils (microns) need to reduce rolling speed to avoid local deformation or bonding due to friction heat.

Shape and surface quality control
Real-time monitoring of the shape of the plate, by adjusting the intermediate roll twitch (within the range of 5~10mm) to eliminate the middle or double wave shape. After cold rolling, the vanadium foil should be pickled (such as hydrochloric acid soaking) to remove the surface oxide layer and rolling oil residue and improve the surface finish.

2, vanadium foil annealing process core requirements
Temperature and time control
The annealing temperature of vanadium foil should be adjusted according to the deformation of vanadium foil in cold rolling: the vanadium foil with large deformation should be annealed above 450~500℃ (recrystallization temperature), and the holding time should be controlled within 2~4 hours to fully eliminate work hardening. The heating speed should be controlled in stages: below 400℃, it can be heated rapidly, and at 400℃ to the target temperature, it is necessary to slow down the heating speed (30~50℃/h) to avoid uneven organization due to the temperature difference between inside and outside.

Interlayer bonding prevention
When annealing vanadium foil, it is necessary to keep the protective gas (such as nitrogen and hydrogen mixture) in good circulation to avoid local heat block resulting in high temperature and inter-layer bonding. The stacking method should avoid tower roll or overflow edge roll, and preferentially place the deformable roll on the upper part of the steel stack to reduce the inter-layer pressure.

Specifications for Equipment safety and operation
Regularly check the temperature control system of the annealing furnace (such as the accuracy of thermocouple insertion and placement) to prevent abnormal material properties or equipment damage caused by overtemperature. To prevent burns or gas poisoning, wear high-temperature protective equipment and use special tools to carry high-temperature vanadium foils

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