Non-oriented electrical steel is moving towards high-performance applications

07 Mar 2024
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In the future, with the in-depth development of energy-saving, intelligent manufacturing and green production in the global manufacturing industry, my country's demand for electrical steel will undergo new changes.

As the industry with the largest consumption of non-oriented electrical steel in my country (according to incomplete statistics, the annual consumption of electrical steel exceeds 4 million tons), the small and medium-sized motor industry has been committed to transformation and upgrading in recent years and has achieved certain results. From the perspective of motor efficiency, ultra-efficient motors such as the YE4 series have been promoted and applied, and the IE5 super-level motor project has been established and research and development has begun. From the perspective of motor lightweighting, small lightweight motors such as high-power ultra-high-speed motors and high-power density motors have been developed. Some products have been applied in compressors and other fields. New ideas have been proposed for thinning silicon steel sheets, reducing losses, and improving magnetic induction intensity. requirements. From the perspective of the application of new motor materials, the motor industry has cooperated with universities to carry out application research on new magnetic materials. For example, waste materials such as silicon steel scraps and melon seeds are used as raw materials, processed into powder metallurgy, and then made into motor cores through molding and sintering. The loss will be less than 2.1W/kg, and the magnetic induction will be greater than 1.7 Tesla. It is expected that the demand for W250, W270, W310 and other silicon steel will increase in the future.

Cold-rolled non-oriented electrical steel refers to cold-rolled electrical steel containing 2.9% ~ 3.5% Si. Its crystal structure has certain regularity and directionality. Generally refers to single-oriented silicon steel sheets with Gaussian texture, that is, silicon steel in which the (110) crystal plane is parallel to the rolling surface and the [001] crystal direction is parallel to the rolling direction. There are also cold-rolled dual-oriented (cubic texture {100}) silicon steel. Function: Cold-rolled oriented silicon steel, also known as cold-rolled transformer steel, is used to manufacture the cores of various transformers.

Non-oriented electrical steel manufacturing process

The key to producing silicon steel with Gaussian texture is the use of secondary recrystallization. In order to achieve secondary recrystallization, it is usually necessary to add normal grain growth inhibitors, such as MnS, to the alloy. Grain growth inhibitors can be dispersedly distributed in the alloy matrix in the form of doping. When secondary recrystallization occurs, they can effectively prevent the normal growth of the matrix grains. At the same time, they are required to be used during subsequent high-temperature annealing. Can be easily removed to avoid deteriorating the product's magnetic properties. In the secondary recrystallization, the orientation nuclei of secondary grain growth mainly rely on appropriate cold rolling process and recrystallization annealing. Since phase transformation destroys grain orientation, it is critical to maintain a single phase during heat treatment.

Hot rolled plates should be cold rolled as soon as possible after normalization and pickling. If the steel is parked for a long time, solid solution carbon and nitrogen in the steel will precipitate to form an unstable second phase, which will weaken the pinning dislocations of carbon and nitrogen during cold rolling. After annealing The size of the re-precipitated AlN increases and the magnetism decreases.

1) Cold rolling method with high reduction rate using AlN as the main inhibitor;

2) Secondary cold rolling method using MnS as the main inhibitor.
Cold rolled non grain oriented electrical steel
CRNGO Silicon Steel
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