Differences in production process between non-oriented silicon steel sheets and oriented silicon steel sheets

- Oct 24, 2019-

(1) The process requirements for non-oriented silicon steel sheets are relatively lower than those for oriented silicon steel sheets. The non-oriented silicon steel sheet is obtained by hot rolling a billet or a continuous casting billet into a coil having a thickness of about 2.3 mm.

When a low silicon product is produced, 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 acidified 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 6-10%. This cold rolling with a small reduction ratio allows the grain to grow and the iron loss to decrease during annealing.

(2) Both of the cold-rolled sheets were finally annealed in a continuous furnace at 850 ° C in a 20% hydrogen-nitrogen mixed atmosphere, and then a phosphate-chromated insulating film was applied. After cold rolling to the thickness of the finished product, the steel strips are mostly 0.35 mm and 0.5 mm thick.

The Bs of cold rolled non-oriented silicon steel is higher than that of oriented silicon steel. Oriented silicon steel sheets require low oxide inclusions in the steel and must contain C0.03-0.05% and inhibitors (second phase dispersed particles or grain boundary segregation elements). The role of the inhibitor is to prevent the growth of the primary recrystallized grains and promote the development of secondary recrystallization, thereby obtaining a high [001] 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.

The thickness of the cold rolled product is 0.28, 0.30 or 0.35 mm. The cold-rolled oriented thin silicon steel strip is made of a 0.30 or 0.35 mm thick oriented silicon steel strip which is pickled, cold rolled and annealed.

Compared with cold-rolled non-oriented silicon steel, oriented silicon steel is much lower than non-oriented silicon steel, magnetic has strong directionality; it has superior high magnetic permeability and low loss characteristics in the easy magnetization rolling direction. The iron loss of the oriented steel strip in the rolling direction is only 1/3 of the transverse direction, the ratio of magnetic permeability is 6:1, the iron loss is about 1/2 of the hot rolled strip, and the magnetic permeability is 2.5 times that of the latter. .