Development of High Speed Steel RollsAuthor : hani Time : 2019/10/22
High-carbon high-speed steel rolls (referred to as high-speed steel rolls) are the hottest roll materials with the shortest development time, the fastest development and the most promising applications. Since its inception in Japan in 1988, it has been widely used in hot rolling mills, hot strip mills, cold strip mills, steel tube mills, section mills and bar and wire mills. The metallographic structure of a typical high-speed steel roll consists of a martensite (or bainite) matrix with high hardness MC, M2C, M6C and M7C3. There are also reports on the research and application of high-speed steel rolls in China. The Iron and Steel Research Institute has pioneered the development of high-speed steel rolls in China and has achieved good results in hot-rolled narrow strip mills and bar mills. Beijing Metallurgical Equipment Research Institute, Xi’an Jiaotong University, Henan University of Science and Technology, Xingtai Roll Factory and WISCO Rolling Mill, etc., subsequently conducted in-depth research on the preparation technology of high-speed steel rolls. The successfully developed high-speed steel rolls have been used in high-speed wire rod mills. And on the bar mill. In China, the solidification process, heat treatment process, mechanical properties and wear resistance of high carbon high speed steel for rolls have been studied in depth. In order to improve the solidification structure of high-speed steel rolls and improve their mechanical properties, the modification treatment method of high-speed steel rolls has been studied in China, and the microstructure and performance of high-speed steel rolls have been significantly improved.
As the vanguard of the domestic steel industry, Baosteel first proposed the new concept of “selection of rolls in the 1990s using rolling mills in the 1990s”, and spent a lot of money to purchase high-speed steel rolls from abroad. At present, the F1～Fs framework rolls of Baosteel’s 1580 mm hot-rolled strip unit have all adopted foreign high-speed steel rolls, which have obvious effects in improving strip quality, extending roll life and increasing rolling mill operation rate. Handan Iron and Steel, Zhugang and Anshan Iron and Steel also introduced 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 rolls mainly use centrifugal foundry (CF), continuous pouring process for cladding (CPC)  and electro slag remelt (ESR). Manufactured, and liquid metal electro slag welding (ESSLM), hot isostatic pressure (HIP) and spray deposition (OSPREY) are still being developed and developed.
The high-speed steel roll is produced by the CPC method, and the degree of freedom in designing the alloy is large, and the roll can be rich in hard VC such as hard VC and M2C (or M6C). Although the centrifugal casting method has an overwhelming advantage in terms of cost, there are solid and liquid phase centrifugal separation phenomena during solidification. In order to avoid this, it is necessary to limit its chemical composition. It is worth noting here that the high-speed steel rolls manufactured by the centrifugal casting method have deep thermal cracks and are liable to cause fine chipping as compared with the high-speed steel rolls manufactured by the CPC method.
Due to the complicated equipment of the high-speed steel roll manufactured by the CPC method, it is still impossible to produce in China, and the ESR method for manufacturing rolls has high energy consumption and is only suitable for manufacturing cold rolls. Centrifugal casting rolls are simple in equipment and high inefficiency. They are the main method for manufacturing high-speed steel rolls, but they are prone to segregation and cracking defects, which have not been solved well in China.
The price of imported high-speed steel rolls from abroad is high. Therefore, the promotion and application of domestic high-speed steel rolls are progressing slowly, which is inconsistent with the status of China’s world’s largest steel producing country. In order to promote the use of high-speed steel rolls, it is of great significance to deeply study the key technologies in the manufacture of high-speed steel rolls, which deserves the attention of the majority of roll developers.