Overview of oriented electrical steel

Oriented electrical steel also called grain oriented flat-rolled electrical steel, which refers to cold-rolled electrical steel that contains 2.9%-3.5% Si and possesses the crystal structure of certain regularity and direction. Oriented electrical steel as an essential magnetically soft material of the power industry is mainly applied to the transformer industry, rectifier industry, reactor industry and large motor industry. According to the release of the Ministry of Commerce, dumping occurs to oriented electrical steel products imported from Japan, South Korea and the EU, which diminishes the oriented electrical steel industry of China. It is decided that anti-dumping duty will be levied for these oriented electrical steel products imported from these countries and regions as of July 23. The tax rate is 37.3%-46.3%. The enforcement period will be five years.

Application fields of oriented electrical steel

Large transformers

Nuclear power plants

Hydropower stations

Development history of oriented electrical steel

Development stage of oriented electrical steel - hot rolled silicon steel (1882-1955)

"The magnetic permeability of oriented electrical steel-iron is thousands to tens of thousands of times higher than that of air. When the iron core is magnetized, its magnetic flux density is high, which can produce a magnetic field that is much stronger than the external magnetic field.". The oriented electrical steel - ordinary hot rolled low carbon steel plate is the earliest soft magnetic material for iron core used in industry. In 1886, Westinghouse Electric Company of the United States first used oriented electrical steel with an impurity content of about 0.4% - hot-rolled low-carbon steel plate to make a transformer laminated core. In 1890, 0.35 mm thick oriented electrical steel - hot rolled low carbon steel sheets were widely used to manufacture motor and transformer cores. However, due to the low resistivity of low-carbon steel, the core loss is large; High carbon and nitrogen content, severe magnetic aging. In 1882, Hardfield, England, began to study silicon steel, and in 1898, published magnetic results of 4.4% Si-Fe alloy. In 1903, the United States obtained the right to use the Hardfield patent. In the same year, the United States and Germany began producing oriented electrical steel - hot rolled silicon steel plates. Mass production began in the United States in 1905. In a short period of time, it has completely replaced ordinary oriented electrical steel - hot-rolled low-carbon steel plate to manufacture motors and transformers, with a core loss more than half lower than ordinary low-carbon steel. The period from 1906 to 1930 was a period when manufacturers and users had a unified understanding of the cost, mechanical properties, and design and manufacturing reform of electrical machines and transformers for oriented electrical steel - hot rolled silicon steel plates, improving product quality, and increasing output.

Development stage of oriented electrical steel - cold rolled electrical steel (1930~1967) [1]

This stage is mainly the development stage of cold rolled ordinary oriented electrical steel (GO) plates. In 1930, Gauss of the United States began conducting a large number of experiments using cold rolling and annealing methods to explore the manufacturing process of oriented silicon steel strips and coils with crystal particles arranged parallel to the rolling direction in a direction that is easily magnetized. In 1933, Gauss produced a 3% Si steel with high magnetic properties along the rolling direction using twice oriented electrical steel - cold rolling and annealing. In 1934, Gauss applied for a patent and published it publicly. In 1935, Armco Steel Co., Ltd. cooperated with Westinghouse Electric Co., Ltd. for production based on Gauss patented technology. After that, oriented electrical steel - Armco Steel Company adopted technologies such as rapid analysis of trace carbon and continuously improved manufacturing processes and equipment to gradually improve product quality. Until 1958, after mastering the two pre process manufacturing processes of MnS inhibitor and slab high-temperature heating, the patented technology for manufacturing oriented electrical steel had been basically improved, and the magnetic properties of the product had been greatly improved and stable. The production of 0.30 mm thick products began in 1959, and 0.27 mm products were produced in 1963. In the early 1940s, Armco Steel began producing cold rolled non oriented electrical steel. During the period from 1963 to 1967, countries such as the United Kingdom and Japan successively stopped producing hot rolled silicon steel plates. Hot rolled silicon steel plates have gradually been replaced by cold rolled non oriented electrical steel and cold rolled oriented silicon steel plates.

Development Stage of High Magnetic Induction Oriented Electrical Steel (1961-1994)

In 1961, Nippon Steel first trial-produced high magnetic induction oriented electrical steel with AlN+MnS comprehensive inhibitor based on the introduction of the Armco patent. In 1964, it began trial production and was named Hi-B, but its magnetism was unstable. After 15 years of continuous improvement, the manufacturing process of Hi-B steel has been gradually improved, and the Z8H brand was officially produced in 1968. Since 1979, Nippon Steel and Kawasaki Corporation have successively produced new grades of 0.30, 0.27, 0.23, and 0.18 mm high magnetic induction oriented electrical steel using technologies to increase silicon content, reduce the thickness of product steel strips, and refine magnetic domains.