Development of High Speed Steel Roll (HSS Roll)
High carbon high-speed steel roll (HSS roll for short) is a hot rolling roll material with the shortest time, the fastest development and the widest application prospect. Since it came out in Japan in 1988, it has been widely used in hot strip roughing mill, hot strip finishing mill, cold strip mill, steel tube mill, section mill, and bar and wire rod mill. The metallographic structure of a typical high-speed steel roll is composed of martensite (or bainite) matrix and high hardness carbides such as MC, M2C, M6C, and M7C3. There are also reports on the research and application of high-speed steel roll in China. The Research Institute of iron and steel takes the lead in developing high-speed steel roll in China and has achieved good results in hot strip mill and bar mill. Beijing Metallurgical Equipment Research Institute, Xi'an Jiaotong University, Henan University of science and technology, Xingtai roll plant, and WISCO roll plant have also conducted in-depth research on the preparation technology of high-speed steel roll, and the successfully developed high-speed steel roll has been used in a high-speed wire rod mill and bar mill. In addition, the solidification process, heat treatment process, mechanical properties and wear resistance of high carbon high-speed steel for roll have been studied. In order to improve the solidification structure and mechanical properties of high-speed steel roll, the modification method of high-speed steel roll was also studied in China, which significantly improved the structure and properties of high-speed steel roll.
Baosteel, as a leader in the domestic iron and steel industry, first put forward the new concept of roll material selection of "using 1990s roll on the rolling mill in 1980s". It took the lead in purchasing high-speed steel roll from abroad at great expense. At present, foreign high-speed steel rolls have been used in the f1-fs stand of Baosteel 1580 mm hot strip mill. The effect is very obvious in improving strip quality, prolonging roll life, and increasing mill operation rate. Handan Iron and Steel Co., Ltd., Zhujiang Iron and Steel Co., Ltd., and Anshan Iron and Steel Co., Ltd. have also imported some high-speed steel rolls from abroad, and accumulated valuable experience in the use, maintenance, and grinding of high-speed steel rolls. High-speed steel roll is mainly manufactured by centrifugal foundry (CF), continuous pouring process for cladding (CPC) and electro slag remelting (ESR) abroad, while liquid metal is made by eslm and hot isostatic pressing (hip) Pressure (hip), and spray deposition forming (Osprey) is still improving and developing.
High-speed steel roll made by the CPC method has a large degree of freedom in alloy design. The roll can be rich in carbide such as VC and M2C (or M6C) with excellent wear resistance. Although centrifugal casting has an overwhelming advantage in cost, there is the centrifugal separation of solid and liquid phases in the solidification process. In order to avoid the above situation, its chemical composition should be limited. It is worth pointing out that compared with the high-speed steel roll made by the CPC method, the high-speed steel roll made by the centrifugal casting method has a deep hot crack and is easy to produce fine fragmentation.
Because the equipment of high-speed steel roll manufactured by CPC method is complex, it can not be produced in our country, but the ESR method is only suitable for cold roll because of its high energy consumption. Centrifugal casting roller is the main method of manufacturing high-speed steel roller because of its simple equipment and high efficiency, but it is easy to produce defects such as segregation and cracks, which has not been well solved in China.
The price of imported high-speed steel roll is high, so the promotion and application of domestic high-speed steel roll are slow, which is not in line with China's position as the world's largest steel production country. In order to promote the use of high-speed steel roll, it is of great significance to study the key technology of high-speed steel roll manufacturing, which is worthy of the attention of the majority of roll development workers.
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Laying Head of Wire Rod Mill
