Current situation of large steel casting production enterprises in China

There are more than 30 large-scale casting production enterprises in China, most of which are large and medium-sized state-owned enterprises. At present, there are only a few manufacturers that can produce steel castings above 200 t, such as first heavy, second heavy and CITIC Heavy Industries. The products of the whole industry are mainly supplied to the domestic market, and a small part of them are exported. The main varieties are large castings for power stations, metallurgical parts and petrochemical equipment, marine equipment, mining equipment and aerospace equipment.

In the past 10 years, some domestic enterprises such as first heavy, second heavy and CITIC Heavy Industries have carried out a lot of research and development and exploration in the field of large castings, and achieved a number of achievements with international advanced level and independent intellectual property rights. Such as the successful development of 300 MW nuclear power large castings and forgings, 550 MW water turbine unit complete sets of large castings and forgings, etc. At present, the largest ordinary carbon steel castings and stainless steel castings that can be produced in China are 450 t and 180 t respectively; It has the ability to produce 700 t liquid steel, cast 500 t steel castings with single weight and 400 t high-quality steel castings at one time.

Although the production of large steel castings in China has made great progress and even stepped into the forefront of the world in terms of production capacity, there are obvious deficiencies in the quality of casting products, especially some high-end products are difficult to meet the needs of the domestic market, and high-end castings still rely on imports. For example, the blanks of upper crown, lower ring and blade castings of 14 units on the left bank of the Three Gorges phase I hydropower project are basically imported from abroad. In the manufacturing of the runner of the left bank unit of the Three Gorges project, both the first heavy and the second heavy tried to cast relevant castings, one blade, one blade, one upper crown and one lower ring. The casting of blade and upper crown has been successfully poured and has been used in the left bank unit. However, because the deformation law of the casting has not been well mastered, the casting blank either has a large machining allowance (fat head and big ears), resulting in low process yield and long machining cycle, or it is incomplete (lack of meat), resulting in a large amount of welding repair. If the blade is in the shape of spatial curved surface, it is required to be processed by 5-axis linkage machine tool. Due to the large machining allowance, the processing cycle of one blade is half a month, and 13 or 15 blades are required for each turbine runner, so the processing capacity can not meet the production needs at all. Among the 12 units on the right bank of the Three Gorges, Dongfang Electric Machinery Co., Ltd. and Harbin Electric Machinery Co., Ltd. won the bid respectively. In terms of water turbine units and generator units, Chinese enterprises have mastered the design and manufacturing technology, but China has not or has not fully mastered the production technology of large castings and forgings. On the other hand, in the process of importing foreign high-end castings, developed countries do not transfer the production technology of large castings, that is, we are still subject to (foreign) people in terms of high-end large castings.

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