Steel can be divided into two categories: ordinary steel and special steel. Special steel, namely special steel, includes high-quality alloy steel and alloy. The alloy may not be iron-based, for example, it can be nickel-based or iron-nickel-based. Special steel includes alloy structural steel, alloy spring steel, alloy tool steel, bearing steel, stainless steel, high temperature alloy, precision alloy, etc.
For decades in our country, electric furnace plants have been called special steel plants, and converter plants or steel complexes have been classified as ordinary steel plants. The China Special Steel Enterprise Association has held 8 member meetings, and the member companies of the Special Steel Association are mainly electric furnace manufacturers.
1. Special steel production process and steel plant type
With the development of continuous casting and out-of-furnace treatment (including hot metal pretreatment and secondary refining of steel) technology since the second half of the 20th century, the steel preparation technology has undergone fundamental changes. The modern steel production process is mainly:
Converter process: blast furnace smelting-hot metal pretreatment-converter refining-secondary refining-continuous casting-(hot delivery and hot charging) rolling;
Electric furnace process: electric furnace smelting-secondary refining-continuous casting-(hot delivery and hot charging) rolling;
Special melting: special melting (vacuum induction melting, cold crucible melting, electroslag remelting, vacuum arc remelting, electron beam remelting, plasma melting or remelting, etc.)-ingot forging or rolling, extrusion.
Modern steelmaking processes are mainly converter processes and electric furnace processes. In 2004, the world’s crude steel output reached 1.0548 billion tons, of which converter steel was 66.52 million tons, accounting for 63%, and electric furnace steel was 356.52 million tons, accounting for 33.8%. The output of special smelting is small, but it is of great significance to the development of national defense, cutting-edge technology, and important national economic sectors.
The types of steel mills have also undergone great changes. Foreign countries (such as the United States) mainly include: Integrated Iron and Steel Company, modern electric furnace steel mills (Mini Mill) and specialized special steel plants (such as Cabot and Allvac) And other specialized electroslag and vacuum metallurgical plants). In addition to steel complexes (such as Wuhan Iron and Steel, Anshan Iron and Steel, Shougang, etc.) and modern electric furnace steel plants (such as Zhujiang Iron and Steel), a number of new types of electric furnace steel complexes (such as Baosteel, Anshan Iron and Steel, Shagang, Xingcheng Special steel, etc.). Some of them have installed modern electric furnaces (Baosteel, Anyang Iron and Steel, etc.) in iron and steel complexes, and some have built converter processes (Shagang, Xingcheng Special Steel, etc.) in enterprises that originally only had electric furnace processes. Due to the small scale of special steel production in my country with special smelting methods (a specialized special smelting factory in the United States can produce several hundred thousand tons per year), special smelting is usually used as a branch or workshop of modern electric furnace steel plants, or as a new A branch or workshop of a modern electric furnace steel plant in a steel complex.
Converter and electric furnace smelting have more and more commonalities. The converter can smelt ordinary steel or special steel; the electric furnace can smelt special steel or ordinary steel. Continuing to refer to the converter plant as a general steel plant and the electric furnace plant as a special steel plant is not true to its name and affects the development of steel plants. In particular, restricting the electric furnace plant to special steel production will affect its development.
2. The proportion of domestic and foreign special steel in total steel output
At present, the world’s special steel production accounts for about 15% of the entire steel production (represented by the United States and Japan). The production and consumption of special steel in the world’s major steel-producing countries are listed in Table 1.
China’s total output of alloy spring steel, alloy structural steel, ball bearing steel, alloy tool steel, high alloy tool steel, and stainless steel in 2003 was 10.98 million tons, and the total output of steel was 222.41 million tons. In 2005, the total output of special steel was 11.32 million tons, and the total output of steel was about 35,000 tons.
It can be seen from the above data that in the world, the proportion of special steel in the United States and Japan is about 15%. Some European countries such as Germany, Sweden, and Italy have a higher proportion, while special steel in my country only accounts for a small part of the total steel. Mainly special steel and high-quality special steel. Special steels are mainly produced by electric furnaces and converters. Further production statistics will find that although converters can also produce special steels, my country’s special steels are currently mainly produced by electric furnaces and should not be produced by converters from individual countries. The ratio is higher than that of electric furnaces and excessive publicity of the advantages of special steel produced by converter plants. The development of special steel is conducive to my country’s transformation from a big steel country to a strong steel country. The focus should be on the development of electric furnace processes.