Process and inhibition of Cold Rolled Non Grain Oriented Electrical Steel

- Feb 26, 2019-

In the process of using cold-rolled amorphous oriented electrical steel, the slab or continuous casting slab is mainly rolled into a coil having a thickness of about 2.3 mm. When manufacturing a low silicon product, the hot rolled coil is pickled and then cold rolled to a thickness of 0.5 mm. When manufacturing high-silicon products, the hot-rolled strip is pickled (or acid-washed after 800-850 °C), cold-rolled to 0.55 or 0.37 mm thick, and annealed at 850 °C in a continuous furnace of hydrogen-nitrogen mixed atmosphere. Cold rolled to a thickness of 0.50 or 0.35 mm at a small reduction of 6 to 10%.

Cold rolling of cold rolled amorphous oriented electrical steel at a small reduction ratio causes grain growth and annealing loss during annealing. Both of the cold-rolled sheets were finally annealed at 850 ° C in a continuous furnace under a 20% hydrogen-nitrogen mixed atmosphere, and then a phosphate-chromated insulating film was applied. Grain-oriented silicon steels generally contain Si3%, which requires low oxide inclusions in the steel and must contain C0.03 to 0.05% and inhibitors (second phase dispersion sites or grain boundary segregation elements).

The effect of the inhibitor of the cold rolled amorphous oriented electrical steel is to prevent the growth of the primary recrystallized grains and promote the development of secondary recrystallization, thereby obtaining a high orientation. The inhibitor itself is detrimental to magnetic properties, so after completion of the inhibition, it must be subjected to high temperature purification annealing. When the second phase inhibitor is used, the slab heating temperature must be increased to solid solution of the original coarse second phase, and then precipitated at a fine particle point during hot rolling or normalization to enhance the inhibition.