Introduction to electroslag remelting development history

The three major breakthroughs in special metallurgy in the 20th century are vacuum metallurgy, plasma metallurgy and electroslag metallurgy. The industrial application of electroslag metallurgy in the world can be traced back to the 1960s.

Development of electroslag furnace remelting at home and abroad

Development of ESR abroad

Electroslag remelting metallurgy originated in submerged arc welding in the United States. The basic principle of electroslag remelting was first proposed by R. K. Hopkins in the United States in 1935, and in March 1939, it was named "Hopkins method" and obtained a US patent. In theory, Hopkins and colleagues mistakenly believed that the remelting process was a "submerged arc discharge" rather than an electroslag process; technically, several issues remained unresolved due to exclusive closed production.

Electroslag remelting metallurgy originated from electroslag welding in the former Soviet Union. The Soviet Union Г.З.Вопошкевич found that the arc was extinguished in the process of arc welding longitudinal seam, the process was stable, and the quality of the weld was excellent, thus electroslag welding was discovered. After 1952, after 5 years of development and research by the Barton Electric Welding Research Institute, in May 1958, under the leadership of Academician Medoval (Б. И. Медовар), in the Ukraine Zaporos City Dnepol Special Steel Company Four 0.5-ton P909 electroslag furnaces were built, and the industrialization of electroslag metallurgy in the Soviet Union kicked off.

Electroslag remelting metallurgy developed rapidly in the 1960s. At that time, in addition to the former Soviet Union, the United States and China, the United Kingdom, Austria, Germany and Japan also conducted in-depth research on electroslag remelting technology. During this period, due to the needs of aerospace and arms race, the Soviet Union carried out a lot of research work on electroslag metallurgy, which greatly promoted the development of electroslag metallurgy. In the United States and Western Europe, through the comparison of electroslag remelting technology and vacuum arc remelting technology from 1959 to 1965, it was realized that electroslag remelting not only simple equipment and operation, low production cost, but also the quality of electroslag steel. In addition to gas content, it is superior to vacuum arc remelting in terms of surface quality, sulfur removal, non-metallic inclusion removal and crystal structure.

The compactness and chemical composition uniformity of the ingot obtained by electroslag remelting are higher than those obtained by vacuum arc remelting, there is no low-magnification defect, and the yield is high. Some well-known companies in the production of vacuum metallurgical equipment began to switch to the manufacture of electroslag furnaces, these companies are: Consarc in the United States, Loybold-Heraeus in the Federal Republic of Germany, Birlec in the United Kingdom, Bohler in Austria and Japan Vacuum Co., Ltd.

In 1967, the first International Conference on Electroslag Remelting was held at Carnegie-Mellon University in Pittsburgh, USA, and after that, an international conference on electroslag remelting or including electroslag remelting was held almost every two years on average.

In the 10 years from 1965 to 1975, electroslag technology has developed rapidly. The development characteristics of electroslag remelting technology during this period are:

(1) The output increases parabolically;

(2) The ingot weight increases geometrically;

(3) Expanded range of electroslag remelting products;

(4) Breaking the boundaries of professions and industries. During the following 10 years (ie 1975-1985), electroslag remelting technology maintained steady development, and electroslag steel production continued to grow. By 1985, the world electroslag steel production reached 1.2 million tons, and the former Soviet Union was about 400,000 to 450,000 tons. tons, about 40,000 to 50,000 tons in Eastern European countries.

Since 1985, electroslag technology has been in a stage of brewing new breakthroughs. At this stage, some companies producing super alloys continued to expand their production capacity, and a number of electroslag furnaces were built and put into operation. For example, Teledyne Allvac Company of the United States established a 23-ton electroslag furnace, and two electroslag furnaces of Inco Alloy International Company were put into production in 1986 to produce Ni-based alloys, Co-based alloys and other heat-resistant alloy ingots and ingots, with a weight of 18 tons. . In 1992, Consarc's 100-ton electroslag furnace was also put into production at a Japanese steel plant.

At the same time, Western Europe and the United States are committed to the electroslag heat capping (BEST) method and the electroslag self-investment mold (MIKW) method to produce large steel ingots. The Ukrainian Barton Electric Welding Research Institute applies bipolar tandem electroslag welding and casting welding to produce large blanks and studies electroslag batch casting to produce large ingots. The Barton Electric Welding Institute uses an electroslag crucible furnace to smelt the required pure molten steel and combines it with centrifugal casting to form electroslag centrifugal casting technology (CESC), which is to pour molten steel into a durable metal mold to form electroslag durable mold casting (EPMC). Entering the 21st century, many new electroslag technologies continue to emerge, such as vacuum electroslag remelting, electroslag continuous casting, electroslag composite casting and rapid electroslag remelting and other new technologies and methods. Electroslag metallurgy has entered the market. A new stage of development.

Development of electroslag refining furnace in China

The electroslag metallurgy technology in my country started early, and the electroslag remelting experiment was carried out in 1958. In November 1959, Professor Zhu Jue of Beijing Iron and Steel Institute led metallurgical teachers and students to cooperate with the Electroslag Laboratory of Metallurgical Construction Research Institute where Li Zhengbang was located, and successfully developed aviation bearing steel by electroslag remelting method. In 1960, small industrial electroslag furnaces were successively completed and put into operation in Chongqing Special Steel Plant, Daye Steel Plant, Dalian Steel Plant and Shanghai Steel No. 5 Plant. 

In November 1961, the former Ministry of Metallurgy held the first National Electroslag Metallurgy Conference in Chongqing, marking that my country's electroslag metallurgy technology has entered a stage of large-scale research and development. Since 1960, my country has held several national electroslag remelting academic conferences to study the metallurgical quality of electroslag remelting, and jointly discuss advanced production methods and furnace experience at home and abroad, as well as the future development direction of electroslag remelting technology. It has played a huge role in promoting the development of electroslag remelting in China.

My country has carried out a lot of research and exploration on electroslag remelting technology, and has successively designed single-phase single-pole, single-phase double-electrode furnace bottom conductive lined electroslag furnace, three-phase consumable electrode three-phase lined electroslag furnace, The closed argon shielded electroslag furnace and the double-electrode arm continuous ingot extraction electroslag furnace, etc., solve the problem of uneven electrode melting during bipolar series remelting by connecting the zero line at the bottom of the furnace. 

In 1981, Shanghai Heavy Machinery Factory cooperated with Beijing Iron and Steel Institute to build a 200-ton three-phase bipolar series electroslag furnace. After being appraised by the state in 1982, it provided 124 pieces of blanks for Qinshan 300MW nuclear power plant, which marked that my country entered the market. The powerhouse of electroslag metallurgy. Since then, induction electroslag furnace and induction electroslag centrifugal casting technology have also been invented.

In recent years, with the rapid development of my country's economy, electroslag metallurgy has shown strong vitality in China, and the second generation of electroslag metallurgy technology has emerged. The second-generation electroslag metallurgy technology is different from the first-generation electroslag metallurgy technology, which mainly has the following characteristics:

First, the products produced are billets instead of ingots, eliminating the need for blooming and billeting;

Second, the entire electroslag process is carried out under the condition of isolating the atmosphere, with a protective atmosphere;

Third, it mainly produces oversized ingots. Representative new electroslag metallurgy technologies include electroslag continuous casting, controlled atmosphere electroslag furnace, large slab electroslag remelting, liquid electroslag casting technology and large electroslag remelting ingot solidification segregation control technology.

In the course of more than 50 years of development of electroslag metallurgy in my country, the scale has been continuously expanded and the technology has been continuously innovated. At present, the production capacity of electroslag steel in my country has exceeded 1 million tons, making it the world's largest producer of electroslag steel. There are also many original works in the theoretical research of electroslag remelting in my country, such as the mechanism of inclusion removal, the optimization and matching of process parameters and the calculation of heat balance, and the development of new slag systems. Northeastern University and other units jointly formulated two international standards for electroslag remelting furnaces in the project "Research and Development of International Standards for my country's Advantageous Technologies". In short, my country is at the world's advanced level in the field of electroslag remelting.

The current development status of electroslag remelting

       In the 21st century, the development of electroslag metallurgy and the demand for electroslag steel products are increasing. From 2005 to 2010, the global output of electroslag steel products showed a trend of increasing year by year. Since 2007, its growth rate has slowed down, and its sales have gradually increased. Since the global financial crisis, the demand has increased.

     In the rapid development of electroslag remelting technology, many furnace types have been formed, which can be divided into two categories according to the power supply mode, including DC electroslag furnace and AC electroslag furnace, among which AC electroslag furnace can be divided into single-phase and multi-phase electroslag furnace. ; According to whether the crystallizer and the furnace are moving, it can be divided into fixed type, crystallizer lifting type, ingot extraction type, and electroslag furnace type where both the crystallizer and the electrode move upward.