Contracted by Shougang Qian'an, China, we supplied seven lines for NGO and GO silicon steel strip by 2013. Included here were not only the mechanical equipment, but also the complete engineering of the electrical and automation systems as well as supervision of erection and commissioning of all lines.
First, the hot strip is annealed and descaled in two annealing and pickling lines capable of processing grain-oriented as well as non-grain-oriented grades. Next in line after the cold rolling process is recrystallization and decarburization in three decarburizing and coating lines. These lines also apply a layer of magnesium oxide to the strips. That prevents the strips from sticking together during the extended high-temperature treatment required for this metallurgical process. Also added at this stage is an insulation varnish which helps introduce inherent stresses to improve the magnetic properties. We installed two flattening and coating lines for final thermal leveling and application of an insulation coating.
Grain-oriented silicon steel strip substantially boosts the energy efficiency of electrical systems. Take for instance energy-efficient transformers. They require grain-oriented electrical sheets with very low core losses. Now, our customer's annual output of GO strip, including highly permeable material, totals 180,000 tons.